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Electronic Supplementary Material (ESI) for Green Chemistry.This journal is The Royal Society of Chemistry 2017Supporting Information forExamples of Xylochemistry: Colorants and PolymersJonas Kühlborna, Ann-Kathrin Dannera,b, Holger Freya, Rishab Iyerc, Anthony J. Arduengo IIIc,*, andTill Opatz.a,*a Institute of Organic Chemistry, Johannes Gutenberg University, Duesbergweg 10 14, 55128 Mainz,Germanyb Graduate School Materials Science in Mainz, Staudingerweg 9, 55128 Mainzc Department of Chemistry, The University of Alabama, Tuscaloosa, Alabama 35487, United StatesTable of contents1General methods .22Experimental procedures .32.1Indigo dye syntheses .32.2Polyamide syntheses .52.2.1Monomer syntheses .52.2.2Polymerizations.103References .114NMR spectra.1254.1Spectra of the indigo dye syntheses .124.2Spectra of the polyamide syntheses .214.2.1Spectra of 4-propylcyclohexanol (2) .214.2.2Spectra of the monomer syntheses.294.2.3Spectra of the polyamides .44Picture of cotton fabric after vat-dyeing with indigo 3 .50S1

1General methodsSolvents were dried and purified, where necessary, by appropriate standard procedures. All otherchemicals were purchased from commercial sources (Sigma-Aldrich, Alfa Aesar, CarbolutionChemicals, Acros Organics) and used as received unless mentioned otherwise. All reactions wereperformed under an inert atmosphere of argon in oven-dried glassware using standard Schlenktechniques unless mentioned otherwise. Reactions under increased pressures were carried out in a typeT316 autoclave (Parr Instruments). Deuterated solvents for NMR measurements were obtained fromDeutereo and used as received. NMR spectra were recorded on a Bruker Avance III HD 300 andBruker Avance III HD 400 spectrometer. Chemical shifts (δ) are reported as parts per million (ppm)downfield from TMS. FT-IR spectra were recorded on a Tensor 27 spectrometer (Bruker) equippedwith a diamond ATR unit. UV spectra were recorded on an Evolution 201 spectrometer (ThermoScientific). HPLC-ESI-MS was performed on a 1200 series HPLC system with a UV diode arraydetector coupled with a LC/MSD trap XCT mass spectrometer (Agilent Technologies).High-resolution masses (ESI) were recorded on a Q-ToF-Ultima 3 instrument (Waters) with aLockSprayTM interface and a suitable external calibrant. Size exclusion chromatography (SEC)measurements in DMF (containing 0.25 g L–1 potassium bromide as additive) were carried out on anAgilent 1100 Series integrated instrument, including a PSS HEMA column (300/100/40·10–10porosity), a UV-detector (detection at 275 nm) and a RI-detector. Poly(ethylene glycol) standardspurchased from Polymer Standards Service were used for calibrations. Matrix-assisted laserdesorption/ionization-time-of-flight-MS (MALDI-ToF-MS) spectra were measured on an Axima CFRMALDI-ToF spectrometer (Shimadzu) equipped with a nitrogen laser delivering 3 ns laser pulses at337 nm using CHCA (α-cyano-4-hydroxycinnamic acid) or HABA (4'-hydroxyazobenzene-2carboxylic acid) as the matrix. The samples were prepared from pyridine and ionized by addinglithium chloride or potassium trifluoroacetate. DSC measurements were carried out on a PerkinElmerDSC 8500 instrument heating from 0 to 170 C at 10 C min–1 under nitrogen using about 3 mg of therespective polymer for analysis. Melting points were determined in open capillary tubes on a KSP I N(Krüss). Thin-layer chromatography (TLC) was carried out on silica gel 60 F254 plates (Merck).Compounds were visualized using UV light and/or by immersion in a solution of KMnO4 (3 g), K2CO3(20 g), 5% aqueous NaOH (5 mL) and water (300 mL) followed by heating. Preparative normal-phasechromatography was performed on silica gel (35-70 µm, Acros Organics) using manual flashchromatography. For dialysis regenerated cellulose membranes with a molecular weight cut-off(MWCO) of 1000 g mol–1 (Cellu Sep) were used.S2

22.1Experimental proceduresIndigo dye syntheses4,5-dimethoxy-2-nitrobenzaldehyde (9)OMeOMeOIn contrast to a procedure of Kumar et al.1 The procedure was carried out in thepresence of normal laboratory lighting. Nitric acid (65%, 100 mL) was cooled toNO20 C and veratraldehyde (8, 20.0 g, 120 mmol) was added with stirring. The mixturewas brought to room temperature, stirred for 3 h and then poured into ice-water (200 mL). Theresulting yellow precipitate was collected by filtration and washed with cold water and ethanol. Thecrude material was dried and recrystallized from ethanol. The product was obtained as a yellow solidand is not light sensitive. Product melting point was checked for subsequent months to identify anychemical transformations that may have occurred due to laboratory light exposure. Melting pointremained at the literature value indicating that the desired product was still present. (23.1 g,̃10.9 mmol, 91%), mp 131–132 C (from EtOH). IR (ATR): νmax 2947, 1682, 1571, 1514, 1397,1354, 1224, 1189, 1058, 793 cm–1. 1H-NMR, COSY (400 MHz, CDCl3): δ 10.45 (s, 1H, CHO),7.61 (s, 1H, H-3), 7.41 (s, 1H, H-6), 4.03 (s, 3H, OCH3-4), 4.02 (s, 3H, OCH3-5) ppm.13C-NMR,HSQC, HMBC (101 MHz, CDCl3): δ 187.8 (CHO), 153.4 (C-4), 152.5 (C-5), 144.0 (C-2), 125.7(C-1), 109.9 (C-6), 107.3 (C-3), 57.0 (OCH3), 56.9 (OCH3) ppm. ESI-MS (pos.): m/z (%) 212.0(100) [M H] , 234.0 (3) [M Na] . The analytical data are in accordance with the oethanol (10)The procedure was conducted following Pandi et al.2 Aldehyde 9 (100 mg,OHMeOMeONO2NO20.47 mmol), Ba(OH)2 8H2O (7.60 mg, 224 µmol) and nitromethane (253 µL,4.73 mmol) were suspended in water (1.5 mL) and stirred at ambienttemperature for 3 h. The reaction mixture was extracted with ethyl acetate (3x5 mL), the combinedorganic extracts were dried over Na2SO4 and evaporated. The yellow product thus obtained (120 mg,̃0.44 mmol, 94%) was used without further purification, mp 139–141 C. IR (ATR): νmax 3511, 2942,1579, 1555, 1333, 1274, 1219, 1088, 799 cm–1. 1H-NMR, COSY (300 MHz, CDCl3): δ 7.67 (s, 1H,H-3), 7.39 (s, 1H, H-6), 6.16 (dd, J 8.94, 2.28 Hz, 1H, H-1’), 4.84 (dd, J 13.70, 2.28 Hz, 1H, Ha2’), 4.50 (dd, J 13.70, 9.94 Hz, 1H, Hb-2’), 4.02 (s, 3H, C5-OCH3), 3.97 (s, 3H, C4-OCH3) ppm.13C-NMR,HSQC, HMBC (76 MHz, CDCl3): δ 154.1 (C-5), 148.8 (C-4), 139.4 (C-2), 129.1 (C-1),109.3 (C-6), 108.0 (C-3), 80.0 (C-2’), 66.9 (C-1’), 56.6 (C5-OCH3), 56.5 (C4-OCH3) ppm. ESI-MS(pos.): m/z (%) 255.6 (100) [M – H2O H] , 295.3 (95) [M Na] . ESI-HRMS (pos.) calcd(C10H12N2O7Na) 295.0542; found 295.0550. The analytical data are in accordance with the literature.3S3

5,5’,6,6’-tetramethoxyindigo (3)OHNMeOMeONHMethod A: According to a procedure from Harley-Mason.4 To aOMestirred suspension of 4,5-dimethoxy-2-nitrobenzaldehyde (9, 2.00 g,OMe9.47 mmol) in acetone (5.00 mL, 68.0 mmol) were added 5 drops ofO10% aqueous NaOH under exclusion of light. After 1 h, water (30 mL) and more 10% aqueous NaOH(5 mL) were added. The resulting mixture was stirred over night at room temperature and left standingwithout stirring for two more days. The precipitate was collected by filtration, washed with boilingethanol (50 mL) and dried in order to obtain a dark blue solid (415 mg, 1.09 mmol, 23%).Method B: The procedure was conducted following Harley-Mason et al.5 Compound 10 (89.0 mg,0.33 mmol) was suspended in water (1.4 mL), 2 M aqueous NaOH solution (383 µL) and sodiumdithionite (172 mg, 0.99 mmol) were added slowly. A dark precipitate of indigo 3 was formed at onceand air was bubbled through the reaction mixture for 15 minutes. The precipitate was collected byfiltration, washed with ethanol (2x10 mL) and diethyl ether (2x10 mL) and dried. The product wasobtained as a dark blue solid (51.0 mg, 0.13 mmol, 81%), mp 325–326 C. λmax (DMSO)/nm 606̃(ε,/dm3 mol–1 cm–1 13383). IR (ATR): νmax 3416, 1612, 1485, 1438, 1294, 1144, 1060, 991, 850, 654cm–1. 1H-NMR, COSY (400 MHz, DMSO-d6): δ 10.00 (s, 2H, H-1, H-1’), 7.01 (s, 2H, H-4, H-4’),6.94 (s, 2H, H-7, H-7’), 3.85 (s, 6H, C-6OCH3, C-6’OCH3), 3.75 (s, 6H, C-5OCH3, C-5’OCH3) ppm.13C-NMR,HSQC, HMBC (101 MHz, DMSO-d6): δ 185.8 (2C, C-3, C-3’), 156.7 (2C, C-6, C-6’),150.3 (2C, C-7a, C-7a’), 144.1 (2C, C-5, C-5’), 121.5 (2C, C-2, C-2’), 110.3 (2C, C-3a, C-3a’), 104.3(2C, C-4, C-4’), 96.2 (2C, C-7, C-7’), 55.8 (4C, OCH3) ppm. ESI-MS (pos.): m/z (%) 383.1 (100)[M H] , 405.1 (0.4) [M Na] . ESI-HRMS (pos.) calcd (C20H18N2O6) 383.1243; found 383.1230.5,5‘,6,6‘-tetrahydroxyindigo (4)OHOHONHHNOHaccordingOHOThe procedure was conducted following Bai et al.6 and -tetramethoxyindigo (3, 2.00 g, 5.23 mmol) in acetic acid(92.0 mL, 1.61 mol) and 48% aqueous HBr solution (92.0 mL, 0.81 mol) was stirred for three daysunder reflux. After cooling to room temperature the mixture was poured into ice-water (200 mL) andthe precipitate was collected by filtration, washed with ethanol (50 mL) and diethyl ether (50 mL). Theresidue was dissolved in 1% aqueous NaOH (50 mL) and the resulting violet solution was filtered. Anequal volume of acetic acid was added to the filtrate. The solution was evaporated and the residue wassuspended in water (20 mL) and filtrated. The residue was again washed with ethanol (20 mL) anddiethyl ether (20 mL). The product was obtained as a black solid (537 mg, 1.65 mmol, 32%),̃mp 370 C. λmax (DMSO)/nm 610 (ε,/dm3 mol–1 cm–1 5887). IR (ATR): νmax 3424, 1659, 1051,1023, 1002, 823, 760, 614 cm–1. 1H-NMR, COSY (400 MHz, DMSO-d6): δ 11.95 (s, 2H, H-1, H1’), 9.75 (s, 2H, OH), 9.25 (s, 2H, H-4, H-4’), 9.11 (s, 2H, OH), 6.82 (s, 2H, H-7, H-7’) ppm.S4

13C-NMR,HSQC, HMBC (101 MHz, DMSO-d6): δ 160.7 (2C, C-3, C-3’), 148.5 (2C, C-6, C-6’),141.7 (2C, C-5, C-5’), 131.7 (2C, C-7a, C-7a’), 125.2 (2C, C-2, C-2’), 112.6 (2C, C-4, C-4’),110.4 (2C, C-3a, C-3a’), 100.3 (2C, C-7, C-7’) ppm.; ESI-HRMS (pos.) calcd (C16H11N2O6)327.0617; found 327.0626.2.22.2.1Polyamide synthesesMonomer syntheses4-propylcyclohexanol (2)OHThe procedure was conducted following Ellwood et al.7 A stainless steel autoclaveequipped with a magnetic stirring bar was charged with 4‘-hydroxypropiophenone(11, 30.0 g, 222 mmol). Distilled water (17 mL, 942 mmol), lactic acid, (85% aq. solution, 1.13 mL,13.3 mmol) and palladium on activated charcoal (10%, 510 mg) were added. After purging withnitrogen and hydrogen three times, the stirring mixture was set under a hydrogen pressure of 20 bar.With the help of an external oil bath, the autoclave was heated to 100 C. At this temperature, themixture was stirred for 3 h. The pressure was raised to 50 bar before heating to 150 C. The mixturewas stirred for about 15 h under these conditions. After cooling to room temperature, the pressure wasreleased and, after purging with nitrogen, the mixture was taken up in ethyl acetate (200 mL). In orderto remove the catalyst the mixture was filtered through Celite. The residue was washed with ethylacetate (200 mL) and the filtrate was washed with saturated NaHCO3 solution (100 mL). The organiclayer was dried over Na2SO4 and evaporated to obtain a colorless liquid (29.0 g, 204 mmol, 92%). Theproduct was obtained as a 1:1-mixture of diastereomers (see 1H-NMR-spectrum S18). These could beseperated by coloumn chromatography (eluent: cyclohexane/ethyl acetate 3:1) in order to characterizethe single diastereomers, but all further syntheses was conducted using the mixture. cis-2: IR (ATR):ν̃ max 3329, 2956, 2924, 2855, 1451, 1368, 1096, 1050, 1011, 951 cm–1. 1H-NMR, COSY, NOESY(400 MHz, CDCl3): δ 3.54 (tt, J 10.9, 4.3 Hz, 1H, H-1), 1.98–1.93 (m, 2H, Ha-2, Ha-6), 1.78–1.70(m, 2H, Heq-3, Heq-5), 1.33–1.13 (m, 7H, Hb-2, H-4, Hb-6, H-1’, H-2’), 0.97–0.91 (m, 2H, Hax-3, Hax5), 0.87 (t, J’ 7.3 Hz, 3H, H-3’) ppm. 13C-NMR, HSQC, HMBC (101 MHz, CDCl3): δ 71.5 (C1), 39.1 (C-1’), 36.6 (C-4), 35.8 (2C, C-2, C-6), 31.4 (2C, C-3, C-5), 20.4 (C-2’), 14.5 (C-3’) ppm.̃trans-2: IR (ATR): νmax 3346, 2955, 2922, 2854, 1456, 1443, 1143, 1049, 1034, 961 cm–1. 1H-NMR,COSY, NOESY (400 MHz, CDCl3): δ 3.95 (m, 1H, H-1), 1.72–1.66 (m, 2H, Ha-2, Ha-6), 1.59–1.47(m, 4H, Hb-2, Ha-3, Ha-5, Hb-6), 1.35–1.20 (m, 7H, Hb-3, H-4, Hb-5, H-1’, H-2’), 0.88 (t, J 7.2 Hz,3H, H-3’) ppm. 13C-NMR, HSQC, HMBC (101 MHz, CDCl3): δ 67.5 (C-1), 38.5 (C-1’), 36.1 (C4), 32.4 (2C, C-2, C-6), 27.2 (2C, C-3, C-5), 20.2 (C-2’), 14.5 (C-3’) ppm. Diastereomeric 2: FD-MS(pos.): m/z (%) 142.4 (100) [M] . bp 78 C (1.5 mbar). The analytical data are in accordance withthe literature.8, 9S5

4-propylcyclohexanone (12)OMethod A: The procedure was conducted following Schultz et al.10 To a 250-mLSchlenk flask equipped with a magnetic stirring bar was added Pd(OAc)2 (379 mg,1.68 mmol) and powdered, freshly activated 3 Å molecular sieves (11 g). THF (23 mL), toluene(150 mL) and TEA (0.48 mL, 3.36 mmol) were added and the flask was evacuated and refilled withoxygen three times before stirring for 30 min under an atmosphere of oxygen at room temperature. Tothis mixture was added alcohol 2 (8.00 g, 56.2 mmol) and stirring was continued for 2 days at roomtemperature. The reaction mixture was filtered through a plug of silica and the residue was washedwith diethyl ether (1 L). The eluate was evaporated in order to obtain a colorless liquid (6.86 g,48.9 mmol, 87%).Method B: The procedure was conducted following Stevens et al.11 To a stirred and cooled (0 C)solution of cyclohexanol 2 (10.3 g, 72.4 mmol) in acetic acid (50 ml) was added dropwise sodiumhypochlorite solution (1.74 M, 50.0 mL, 84.4 mmol). The resulting solution was stirred for 2 h at 0 Cand for 1 h at room temperature. Subsequently, saturated aqueous sodium bisulfite solution (4 mL)was added until the color of the reaction mixture changed from yellow to colorless. The mixture waspoured into an ice-brine mixture (150 mL) and extracted with diethyl ether (6x100 mL). The etherlayer was washed with aqueous 5% NaOH solution (600 mL) until the aqueous washes were basic(checked with pH test paper). The combined aqueous layers were then extracted with diethyl ether(5x50 mL), the organic layers were combined and dried over Na2SO4. After evaporation of the solventand distillation under reduced pressure (bp 47 C, 1.5 mbar) the product was obtained as a colorless̃liquid (9.95 g, 71.0 mmol, 98%). IR (ATR): νmax 2956, 2926, 2861, 1716, 1460, 1421, 1332, 1173,1124, 944, 738 cm–1. 1H-NMR, COSY (300 MHz, CDCl3): δ 2.42–2.26 (m, 4H, H-2, H-6), 2.09–1.99 (m, 2H, Ha-3, Ha-5), 1.76–1.65 (m, 1H, H-4), 1.45–1.23 (m, 6H, Hb-3, Hb-5, H-1’, H-2’), 0.92 (t,J 7.0 Hz, 3H, H-3’) ppm. 13C-NMR, HSQC, HMBC (76 MHz, CDCl3): δ 212.8 (C-1), 41.0 (2C,C-2, C-6), 38.0 (C-1‘), 35.9 (C-4), 32.9 (2C, C-3, C-5), 20.6 (C-2‘), 14.4 (C-3’) ppm. ESI-MS (pos.):m/z (%) 141.1 (100) [M H] , 163.0 (7) [M Na] . bp 47 C (1.5 mbar). The analytical data arein accordance with the literature.8, 9N-hydroxy-4-propylcyclohexanimine (13)NOHIn accordance to a procedure from Hardy et al.12 A solution of 12 (240 mg,1.71 mmol), hydroxylamine hydrochloride (238 mg, 3.43 mmol) and Na2CO3(544 mg, 5.14 mmol) in MeOH (2 mL) and water (1 mL) was stirred at room temperature for 2.5 h.The reaction mixture was evaporated and the residue was taken up in ethyl acetate (15 mL) and water(15 mL). The layers were separated and the aqueous layer was extracted with ethyl acetate (3x10 mL).The combined organic extracts were washed with brine (15 mL), dried over Na2SO4 and evaporated tõobtain a colorless oil (252 mg, 1.62 mmol, 96%). IR (ATR): νmax 3225, 3116, 2954, 2920, 1667, 1441,S6

1008, 971, 914 cm–1. 1H-NMR, COSY, NOESY (400 MHz, CDCl3): δ 8.51 (s, 1H, OH), 3.29–3.20(m, 1H, Heq-6), 2.44–2.38 (m, 1H, Heq-2), 2.08 (dt, J 13.6, 4.8 Hz, 1H, Hax-2), 1.93–1.85 (m, 2H,Heq-3, Heq-5), 1.79 (dt, J 14.5, 5.3 Hz, 1H, Hax-6), 1.55–1.45 (m, 1H, H-4), 1.38–1.28 (m, 2H, H-2’),1.26–1.18 (m, 2H, H-1’), 1.17–1.04 (m, 2H, Hax-3, Hax-5), 0.89 (t, J 7.2 Hz, 3H, H-3’) ppm.13C-NMR,HSQC, HMBC (101 MHz, CDCl3): δ 160.9 (C-1), 38.5 (C-1‘), 36.7 (C-4), 32.9 (C-3),31.7 (C-5), 31.5 (C-2), 24.0 (C-6), 20.3 (C-2‘), 14.4 (C-3’) ppm. ESI-MS (pos.): m/z (%) 156.0(100) [M H] , 178.0 (1) [M Na] . ESI-HRMS (pos.) calcd (C9H18NO) 156.1388; found 156.1389.The analytical data are in accordance with the literature.135-propylazepan-2-one (5)OThe procedure was conducted following Powell et al.14 Oxime 13 (120 mg,NH0.77 mmol) was dissolved in polyphosphoric acid (4.4 g) under gentle warming. Theresulting solution was stirred at 55 C for 18 h. After cooling to room temperature,the mixture was quenched with ice-cold water (2.2 mL) and neutralized with 4 M NaOH (25 mL). Thesolution was extracted with DCM (3x15 mL), the combined organic extracts were dried over Na2SO4and evaporated. The product was obtained as a colorless solid (104 mg, 0.67 mmol, 87%),̃mp 80–81 C. IR (ATR): νmax 3199, 3072, 2954, 2910, 2852, 1660, 1440, 1356, 1225, 1120, 851 cm–1. 1H-NMR,COSY (400 MHz, CDCl3): δ 6.65 (s, 1H, H-1), 3.29–3.22 (m, 2H, H-7), 2.54–2.43 (m,2H, H-3), 1.90–1.82 (m, 2H, Ha-4, Ha-6), 1.58–1.50 (m, 1H, H-5), 1.36–1.18 (m, 6H, Hb-4, Hb-6, H-1‘,H-2‘), 0.89 (t, J 7.1 Hz, 3H, H-3‘) ppm. 13C-NMR, HSQC, HMBC (101 MHz, CDCl3): δ 179.5(C-2), 42.2 (C-7), 41.4 (C-5), 39.4 (C-1‘), 35.6 (C-6), 34.9 (C-3), 29.1 (C-4), 20.0 (C-2‘), 14.3 (C-3’)ppm. ESI-MS (pos.): m/z (%) 156.1 (85) [M H] , 178.1 (14) [M Na] , 311.3 (100) [2M H] ,333.2 (16.4) [2M Na] . ESI-HRMS (pos.) calcd (C9H18NO) 156.1388; found 156.1385. Theanalytical data are in accordance with the literature.153-propylhexanedioic acid (6)Method A:Step 1: 4-propylcyclohex-1-eneThe procedure was conducted following Coleman et al.16 Cyclohexanol 2 (13.0 g,91.4 mmol) and concentrated sulfuric acid (274 µL, 483 µmol) were placed in a 50-mLround-bottom flask equipped with a distillation attachment. The mixture was placed in a preheated oilbath at 150 C and was stirred under diminished pressure of 200 mbar. The receiver was kept coldthrough an external ice bath and the distillation was continued until only a small residue remained.The distillate was dissolved in DCM (200 mL) and washed with brine (50 mL). The organic layer wasdried over Na2SO4 and concentrated under a pressure of 350 mbar. The product was obtained as aS7

colorless liquid (6.55 g, 48.0 mmol, containing 9 mol% DCM, see 1H-NMR-spectrum S35) and wasused without further purification in the next step.Step 2: 3-propylhexanedioic acid (6)The procedure was conducted following Zimmermann et al.17 To a stirredsuspension of 4-propylcyclohex-1-ene (6.55 g, 48.0 mmol, containing 9 mol%OHOOHODCM) and sodium periodate (42.4 g, 198 mmol) in water (240 mmol), ethylacetate (95 mL) and acetonitrile (95 mL) was added RuCl3·xH2O (48% Ru,240 mg, 1.14 mmol). The resulting mixture was stirred vigorously for 2 h at room temperature. Afterphase separation, the aqueous layer was extracted with ethyl acetate (3x100 mL). The combinedorganic extracts were concentrated under diminished pressure to 50 mL, quickly extracted with 1 MNaOH (3x25 mL) and the aqueous extracts were again acidified with 2 M hydrochloric acid. Thissolution was extracted with ethyl acetate (3x50 mL) and the combined organic extracts were driedover Na2SO4 and evaporated. The black residue was eluted through a plug of silica (eluent:cyclohexane:ethyl acetate:acetic acid 100:100:1) in order to remove inorganic salts. The product wasobtained as a colorless oil (8.54 g, 45.4 mmol, 74% over two steps).Method B:The procedure was conducted following Rokhum et al.18 A suspension of Oxone (70.2 g, 228 mmol)in water (86 mL) was added to cyclohexanone 12 (8.00 g, 57.1 mmol) and RuCl3·xH2O (48% Ru,59.2 mg, 0.29 mmol). The resulting mixture was allowed to stir over night at room temperature andwas subsequently extracted with ethyl acetate (3x100mL). The combined organic extracts were driedover Na2SO4 and evaporated. The resulting black oil was eluted through a plug of silica (eluent:cyclohexane:ethyl acetate:acetic acid 100:100:1) in order to remove inorganic salts and the product̃was obtained as a colorless oil (7.54 g, 39.9 mmol, 70%). IR (ATR): νmax 2958, 2932, 2874, 1702,1456, 1412, 1381, 1286, 1235, 1162, 934 cm–1. 1H-NMR, COSY (300 MHz, CDCl3): δ 11.01 (s,2H, OH), 2.44–2.36 (m, 2H, H-5), 2.36–2.25 (m, 2H, H-2), 1.96–1.88 (m, 1H, H-3), 1.73–1.63 (m,2H, H-4), 1.37–1.27 (m, 4H, H-1’, H-2’), 0.90 (t, J 6.3 Hz, 3H, H-3’) ppm.13C-NMR,HSQC,HMBC (76 MHz, CDCl3): δ 180.3 (C-6), 179.9 (C-1), 38.7 (C-2), 35.9 (C-1’), 34.1 (C-3), 31.5(C-5), 28.6 (C-4), 19.7 (C-2’), 14.3 (C-3’) ppm. ESI-MS (pos.): m/z (%) 189.0 (8.6) [M H] , 211.0(100) [M Na] . ESI-HRMS (pos.) calcd (C9H16O4Na) 211.0946; found 211.0952.3-propylhexanediamide (15)The procedure was conducted following Treibs et al.19 A solution of diacid 6OH2 N(5.78 g, 30.8 mmol) in freshly distilled thionyl chloride (6.70 mL, 92.4 mmol)NH2Owas stirred for 1 h under reflux. After cooling to room temperature, excessthionyl chloride was removed under reduced pressure to obtain the crude acylchloride which was used directly. The crude acyl chloride was added to an ice-cold solution of a 25%S8

aqueous ammonia solution (27.9 mL, 370 mmol) over 15 min. After removal of the ice bath, themixture was stirred for 15 min at room temperature and the precipitate was collected by filtration. Theresidue was washed with water and dried in order to obtain a colorless solid (4.3 g, 23.1 mmol, 75%̃over two steps), mp 147–149 C. IR (ATR): νmax 3385, 3189, 2955, 2927, 2872, 1649, 1412, 1170cm–1. 1H-NMR, COSY (400 MHz, DMSO-d6): δ 7.25 (s, 1H, C-1NHa), 7.23 (s, 1H, C-6NHa), 6.71(s, 1H, C-1NHb), 6.68 (s, 1H, C-6NHb), 2.04–1.98 (m, 2H, H-5), 1.95 (d, J 7.6 Hz, 2H, H-2),1.77–1.70 (m, 1H, H-3), 1.49–1.40 (m, 2H, H-4), 1.29–1.15 (m, 4H, H-1‘, H-2‘), 0.84 (t, J 7.0 Hz,3H, H-3‘) ppm. 13C-NMR, HSQC, HMBC (101 MHz, DMSO-d6): δ 174.5 (C-6), 173.9 (C-1), 39.9(C-2), 35.4 (C-1’), 34.0 (C-3), 32.5 (C-5), 29.2 (C-4), 19.0 (C-2’), 14.3 (C-3’) ppm. ESI-MS (pos.):m/z (%) 187.1 (30) [M H] , 209.1 (100) [M Na] , 395.2 (80) [2M Na] . ESI-HRMS (pos.)calcd (C9H18O2N2Na) 209.1266; found 209.1261. The analytical data are in accordance with theliterature.203-propylhexane-1,6-diamine (7)Method A: The procedure was conducted following Reynolds et al.21 To aH2 Nstirred suspension of lithium aluminium hydride (1.42 g, 37.6 mmol) in dryNH2MTBE (280 mL) was added diamide 15 (2.00 g, 10.7 mmol) over a period of10 minutes. The resulting mixture was stirred for 16 h under reflux. After cooling to 0 C1 M potassium sodium tartrate solution (90 mL) was added slowly. The resulting precipitate wasremoved by filtration and the residue was washed with ethyl acetate (200 mL). After separation of thelayers the aqueous phase was extracted with ethyl acetate (3x30 mL) and the combined organic layerswere dried over Na2SO4 and evaporated. In order to obtain a pure product the residue was distilledusing a Kugelrohr apparatus under vacuum (bp 120–135 C, 1 mbar). The product was obtained as ayellow liquid (1.20 g, 7.60 mmol, 71%).Method B: The procedure was conducted following Malkov et al.22 To a stirred solution of diamide 15(500 mg, 2.68 mmol) in dry THF (6.30 mL) was added a 1 M solution of BH3·THF complex in THF(25.5 mL, 25.5 mmol). The resulting solution was stirred for 1 h at room temperature and for 5 h at70 C. The mixture was then cooled to 0 C and MeOH (5 mL) was added. After stirring over night atroom temperature, the solvent was evaporated, 6 M aqueous HCl (50 mL) was added to the residue andthe mixture was stirred for 4 h under reflux. The solvent was removed with a constant stream ofnitrogen overnight and the residue was extracted with MeOH (3x15 mL). After evaporation of thesolvent the residue was taken up with 1 M aqueous KOH (70 mL) and extracted with diethyl ether(6x20 mL). The combined organic layers were dried over Na2SO4 and evaporated to give a yellow oil̃(314 mg, 1.99 mmol, 74%). IR (ATR): νmax 3281, 2954, 2923, 2858, 1669, 1601, 1456, 1378, 1296,1070, 817 cm–1. 1H-NMR, COSY (300 MHz, CDCl3): δ 2.71–2.64 (m, 4H, H-1, H-6), 1.56 (s, 4H,NH), 1.54–1.22 (m, 12H, H-2, H-3, H-4, H-5, H-1‘, H-2‘), 0.87 (t, J 6.8 Hz, 3H, H-3‘) ppm. 13C-S9

NMR, HSQC, HMBC (76 MHz, CDCl3): δ 42.8, 40.0, 38.0, 36.2 (C-1’), 35.0 (C-3), 30.9, 30.8,19.9 (C-2’), 14.6 (C-3’) ppm. ESI-HRMS (pos.) calcd (C9H23N2) 159.1861; found 159.1865.2.2.2PolymerizationsAnionic polymerization of lactam 5 with potassiumThe procedure was conducted following Winnacker et al.23OPhNHThe dried lactam 5 (560 mg, 3.60 mmol) and potassiumOHNOHO(7.5 mg, 0.18 mmol) were placed in a Schlenk flask underargon. The stirred mixture was evacuated and heated ton150 C. Upon reaching this temperature, the flask was flushed with argon again and benzoyl chloride(12 µL, 0.09 mmol) was added. The mixture was evacuated and stirred for 7 hours at 150 C. Aftercooling to room temperature, the residue was washed with hexane:ethyl acetate 1:1 (3x10 mL) andwater. The remaining brown solid was dissolved in methanol (0.5 mL) and purred into cold(–20 C) diethyl ether (30 mL) in order to precipitate the polyamide which was separated bycentrifugation. The insoluble fraction was taken up in MeOH (4 mL) and dialysed in MeOH (1 L) for24 h using regenerated cellulose membranes (MWCO 1000 g mol–1). After drying, the polyamide was̃obtained as a yellowish solid (291 mg, 1.88 mmol, 52%), DSC Tg 15 C. IR (ATR): νmax 3282, 2955,2927, 2869, 1637, 1546, 1454, 1377, 1313, 697 cm–1. 1H-NMR, COSY (400 MHz, DMSO-d6): δ 7.84–7.81 (m, benzoyl o-positions), 7.74 (s, NH), 7.51–7.48 (m, benzoyl p-position), 7.45–7.42 (m,benzoyl m-positions), 3.03–2.97 (m, NH-CH2), 2.01–1.99 (m, CO-CH2), 1.46–1.44 (m, CO-CH2-CH2),1.33–1.15 (m, H-1’, H-2’, CH, NH-CH2-CH2), 0.83 (t, J 7.0 Hz, H-3’) ppm.13Cinverse gated-NMR,HSQC, HMBC (101 MHz, DMSO-d6): δ 172.5 (CO), 166.5 (terminal benzoyl CO), 135.2 (terminalbenzoyl C-1), 131.4 (terminal benzoyl p-position), 128.7 (2C, terminal benzoyl m-position), 127.5(2C, terminal benzoyl o-position), 36.8 (NH-CH2), 35.5 (C-1’), 34.6 (CH), 33.3 (NH-CH2-CH2), 33.2(CO-CH2), 29.1 (CO-CH2-CH2), 19.5 (C-2’), 14.7 (C-3’) ppm.Polycondensation of 7 with the acid chloride of 6The procedure was conducted following Wu et al.24 andOHOONHHNmodified according to Sudo et al.25 The dicarboxylic acid 6H(250 mg, 1.33 mmol) was converted to the correspondingnacyl chloride by refluxing in freshly distilled thionyl chloride(575 µL, 7.98 mmol) for an hour. Excess thionyl chloride was removed by evaporation at roomtemperature. This crude acyl chloride was then dissolved in dry DMAc (2.5 mL) and added to asolution of diamine 7 (210 mg, 1.33 mmol) and dry triethylamine (374 µL, 2.66 mmol) in dry DMAc(2.5 mL). The reaction mixture was stirred overnight at room temperature and then poured into 5%aqueous NaHCO3 solution (25 mL). The precipitate was collected by filtration and washed with waterand acetone. The residue was taken up in MeOH, concentrated by evaporation (to 1 mL) and pouredS10

into cold (–20 C) diethyl ether (30 mL). After centrifugation, the insoluble fraction was taken up withMeOH (3.5 mL) and dialysis in MeOH (1 L) was conducted for 24 hours using regenerated cellulosemembranes (MWCO 1000 g mol–1). The polyamide was obtained as a yellowish solid (254 mg,̃0.84 mmol, 62%), DSC Tg 28 C. IR (ATR): νmax 3284, 2955, 2927, 2869, 1638, 1547, 1454, 1376,1251, 737 cm–1. 1H-NMR, COSY (400 MHz, DMSO-d6): δ 7.85–7.73 (m, 2H, NH), 3.03–2.94 (m,4H, NH-CH2), 2.03–1.94 (m, 4H, CO-CH2), 1.74–1.70 (m, 1H, CO-CH2-CH), 1.46–1.13 (m, 17H,H-1’, H-2’, H-1’’, H-2’’, 2xNH-CH2-CH2, NH-CH2-CH2-CH, NH-CH2-CH2-CH2, CO-CH2-CH2),0.85–8.80 (m, 6H, H-3’, H-3’’) ppm.13C-NMR,HSQC, HMBC (101 MHz, DMSO-d6): δ 172.0(CO-CH2-CH2), 171.3 (CO-CH2-CH), 40.1 (CO-CH2-CH), 38.7 (NH-CH2), 36.2 (NH-CH2), 35.2 (2C,C-1’, C-1’’), 34.1 (CO-CH2-CH), 33.9 (CH), 33.0, 32.8 (CO-CH2-CH2), 30.1, 29.3 (CO-CH2-CH2),26.0, 19.0 (C-2’), 18.9 (C-2’’), 14.2 (2C, C-3’, C-3’’) ppm.3References12S. Kumar, E. J. Wachtel and E. Keinan, J. Org. Chem., 1993, 58, 3821–3827.M. Pandi, P. K. Chanani and S. Govindasamy, Applied Catalysis A: General, 2012, 441–442,119–123.R. A. Heacock and O. Hutzinger, Can. J. Chem., 1963, 41, 543–545.J. Harley-Mason, J. Chem. Soc., 1948, 1244–1247.R. H. Horn, R. B. Miller, S. N. Slater, M. W. Partridge, F. Bell, W. H. Hunter, G. Anderson, N.Campbell, G. T. Newbold, W. F. Beech, N. Legg, J. Harley-Mason, A. G. Sharpe and H. Kacser,J. Chem. Soc., 1950, 2900–2908.M. Bai, J. Huang, X. Zheng, Z. Song, M. Tang, W. Mao, L. Yuan, J. Wu, X. Weng and X. Zhou,J. Am. Chem. Soc., 2010, 132, 15321–15327.WO Pat., 2002014253 A1, 2002.B. Gauthier, Ann. Chim., 1945, 20, 581–608.T. Q. Hu

Jonas Kühlborna, Ann-Kathrin Dannera,b, Holger Freya, Rishab Iyerc, Anthony J. Arduengo IIIc,*, and Till Opatz.a,* a Institute of Organic Chemistry, Johannes Gutenberg University, Duesbergweg 10 14, 55128 Mainz, Germany b Graduate School Materials Science in Mainz, Staudingerweg 9, 55128 Mainz