Supporting Information Wiley-VCH 2007 69451 Weinheim, Germany
A Distinctive Organocatalytic Approach to Complex Macromolecular Architectures Olivier Coulembier, Matthew 5. 5iesewetter, Andrew Mason, Philippe Dubois, >ames L. Hedrick, Robert M. Daymouth Experimental Procedure!"#-Lactide was obtained from Purac and used without further purification (water content K 0.02 N). bis-hydroxyl terminated Poly(ethylene glycol)s (PEO-(OH) 2, M n R 3400) were purchased from Aldrich and dried under vacuum at 60VC overnight prior to three azeotropic distillations from toluene. Amino-terminated PEGs were prepared by cyanoethylation of PEG-(OH) 2 or PEG-(NH 2 ) 2 followed by reduction. 1,3,4-triphenyl- 4,5-dihydro-1H-1,2-triazol-5-ylidene (from Acros) was purified by exposure to high vacuum at 90VC overnight. Benzene-$ %, purchased from Aldrich, was dried over Na]benzophenone and degassed by standard procedures. &'"()*+,'-"+.)(/)0/,'$!)1'2+*!3.("+*$/456// 7&&8 9 &8 9 :;&8 9 &8 9 :<&8 9 &8 9 &7/ Hydroxy-terminated PEG (= n R 3400, 10.0 g, 2.94 mmol) was dissolved in excess acrylonitrile (25 ml) in a round-bottom flask. The clear solution was cooled to 0 VC in an ice water bath, and a small amount of sodium hydride (60N dispersion in mineral oil, 15 mg, 0.4 mmol) was added to start the reaction. After 15 minutes at 0 VC, the pale yellow reaction mixture was _uenched with a few drops of concentrated hydrochloric acid. Excess acrylonitrile was removed under vacuum and the product was dissolved in CH 2 Cl 2. Insoluble poly(acrylonitrile) was removed by filtration through a plug of Celite, giving a clear, colorless solution. Solvent removal gave the nitrile-terminated PEG as a white solid (8.90 g, 86N). 1 H NMR (CDCl 3, 400 MHz):! 3.70 (t, 4H, > R 6.4 Hz, OC8 2 CH 2 CN), 3.63 (br s, PEG C8 2 ), 2.60 (t, 4H, > R 6.4 Hz, OCH 2 C8 2 CN). 13 C NMR (CDCl 3, 100 MHz):! 117.9 (OCH 2 CH 2 &N), 70.5 (PEG &H 2 ), 65.9 (O&H 2 CH 2 CN), 18.8 (OCH 2 &H 2 CN). &'"()*+,'-"+.)(/)0/"3.(*2+*!3.("+*$/456/ ;7&&8 9 &8 9 < 9 7&8 9 &8 9 &8 9 :;&8 9 &8 9 :<&8 9 &8 9 &8 9 7;&8 9 &8 9 &7< 9 / Amine-terminated PEG (= n R 3510, 5.0 g, 1.42 mmol) was dissolved in methanol (20 ml) and excess acrylonitrile (20 ml) to give a clear solution. The flask was sealed and stirred at 60 VC for six hours. After cooling, the solvent was removed under vacuum. The product was dissolved in CH 2 Cl 2, filtered, and dried to give a white solid (4.95 g, 93N). 1 H NMR (CDCl 3, 400 MHz):! 3.63 (br s, PEG C8 2 ), 3.52 (t, 4H, > R 6.0 Hz, OC8 2 CH 2 CH 2 N), 2.81 (t, 8H, > R 6.4 Hz, NC8 2 CH 2 CN), 2.61 (t, 4H, > R 6.4 Hz, OCH 2 CH 2 C8 2 N), 2.47 (t, 8H, > R 6.4 Hz, NCH 2 C8 2 CN), 1.68 (p, 4H, >/ R 6.0 Hz, OCH 2 C8 2 CH 2 N). 13 C NMR (CDCl 3, 100 MHz):! 118.6 (NCH 2 CH 2 &N), 70.3 (PEG &H 2 ), 67.6 (O&H 2 CH 2 CH 2 N), 49.5 (N&H 2 CH 2 CN), 49.2 (OCH 2 CH 2 &H 2 N), 27.2 (OCH 2 &H 2 CH 2 N), 16.6 (NCH 2 &H 2 CN). - 1 -
6*(*!"-/?!)#*$@!*/0)!/(.+!.-*/!*$@#+.)(/ A dry Schlenk flask e_uipped with a reflux condenser was placed under nitrogen and charged with dry THF (50 ml). A syringe was used to add an excess (usuall two- to fourfold) of BH 3 dthf solution (1.0 = in THF). This mixture was cooled to 0 VC in an ice bath. The nitrile-terminated PEG was also dissolved in a minimum amount of dry THFe in most cases heating was re_uired to obtain a homogeneous solution. The PEG solution was added slowly to the borane solution, then allowed to stir for 30 minutes at 0 VC. The reaction was then heated at reflux under nitrogen overnight. After cooling in an ice bath, the flask was opened and methanol was slowly added to react with excess borane (with hydrogen evolution). Concentrated HCl (2 ml) was added, and the mixture was stirred at 0 VC for one hour. The solvent was removed under vacuum, residues were taken up in methanol and dried under vacuum to remove trimethyl borate side products. The resulting polymer was dissolved in a_ueous sodium hydroxide (1= solution). The polymer was thoroughly dried under vacuum, dissolved in CH 2 Cl 2, filtered through Celite, and precipitated in ether, giving a fine white powder. 8 9 7&8 9 &8 9 &8 9 :;&8 9 &8 9 :<&8 9 &8 9 &8 9 78 9 / Nitrile-terminated PEG (5.00 g, 1.43 mmol) was reacted with excess BH 3 dthf solution (20 ml, 20 mmol) as described above to give the desired amine-terminated PEG as a white powder (4.30 g, 86N). 1 H NMR (CDCl 3, 400 MHz):! 3.63 (br s, PEG C8 2 ), 3.56 (t, 4H, > R 6.4 Hz, OC8 2 CH 2 CH 2 NH 2 ), 2.81 (t, 4H, > R 6.8 Hz, OCH 2 CH 2 C8 2 NH 2 ), 1.74 (p, 4H, > R 6.4 Hz, OCH 2 C8 2 CH 2 NH 2 ), 1.10 (br s, 4H, OCH 2 CH 2 CH 2 N8 2 ). 13 C NMR (CDCl 3, 100 MHz):! 70.5 (PEG &H 2 ), 69.5 (O&H 2 CH 2 CH 2 NH 2 ), 39.6 (OCH 2 CH 2 &H 2 NH 2 ), 33.1 (OCH 2 &H 2 CH 2 NH 2 ). ;8 9 7&8 9 &8 9 &8 9 < 9 7&8 9 &8 9 &8 9 :;&8 9 &8 9 :<&8 9 &8 9 &8 9 7;&8 9 &8 9 &8 9 78 9 < 9 / Tetranitrile-terminated PEG (2.50 g, 0.67 mmol) was reacted with excess BH 3 dthf solution (20 ml, 20 mmol) as described above to give the desired tetraamine-terminated PEG as a white powder (2.10 g, 84N). 1 H NMR (CDCl 3, 400 MHz):! 3.63 (br s, PEG C8 2 ), 3.46 (t, 4H, >/ R 6.4 Hz, OC8 2 CH 2 CH 2 N), 2.72 (t, 8H, > R 6.8 Hz, NCH 2 CH 2 C8 2 NH 2 ), 2.44 (t, 4H, > R 6.8 Hz, OCH 2 CH 2 C8 2 N), 2.42 (t, 8H, > R 6.8 Hz, NC8 2 CH 2 CH 2 NH 2 ), 1.69 (p, 4H, > R 6.4 Hz, OCH 2 C8 2 CH 2 N), 1.58 (p, 8H, > R 6.8 Hz, NCH 2 C8 2 CH 2 NH 2 ), 1.15 (br s, NCH 2 CH 2 CH 2 N8 2 ). 13 C NMR (CDCl 3, 100 MHz):! 70.5(PEG &H 2 ), 69.6 (O&H 2 CH 2 CH 2 N), 51.9 (OCH 2 CH 2 &H 2 N), 50.8 (N&H 2 CH 2 CH 2 NH 2 ), 40.6 (NCH 2 CH 2 &H 2 NH 2 ), 30.4 (OCH 2 &H 2 CH 2 N), 27.1 (NCH 2 &H 2 CH 2 NH 2 ). 6*(*!"-/?)-'3*!.A"+.)(/?!)#*$@!*B In a drybox, an NMR tube e_uipped with a >- foung valve was charged with!"#-lactide (29.7 mg, 2.06 x 10-1 mmol), 1,3,4-triphenyl- 4,5-dihydro-1H-1,2-triazol-5-ylidene (2.9 mg, 9.76 x 10-3 mmol) and PEO-(NH 2 ) 2 (9.2 mg, 2.40 x 10-3 mmol) in 0.6 ml of dry benzene-$ %. The sealed NMR tube was then heated at 90VC in an oil bath. After 3 days (conv R 84.3N), the reaction was cooled to room temperature and _uenched with g0.5 ml of carbon disulfide and returned to reflux for 1 hr. The polymer was precipitated twice from cold heptane. The resulting polymer, slightly pink in color indicating the presence of CS 2 -triazole adduct, can be dissolved in CS 2 at 90VC and precipitated by returning to room temperature. The red CS 2 solution can - 2 -
be decanted leaving behind white polymer. Isolated polymer is dried under high vacuum until constant weight (31.3 mg, 80.5N, PDI R 1.09, = n R 9,580), and the degree of polymerization was determined by 1 H-NMR spectroscopy (DP R 48). 300 MHz 1 H-NMR (CDCl 3 ):! 1.41-1.70 (m, -CH 3 h -nch 3 ), 3.62 (s, -n(ch 2 -CH 2 -O)-), 4.32 (_, -CH-), 5.07-5.22 (m, -nch). For polymerizations with the diol, a single catalyst]initiator species was made by stirring PEO-(OH) 2 with excess 1 for 1 hour in toluene, followed by precipitation from solution with cold heptane and isolation. The PEO-(1) 2 adduct is stable at room temperature. rac-lactide polymerizations with this species proceed identically to the telechelic polyamine species. Failure to dry the PEO-(OH) 2 in this manor results in short oligomeric fragments of PLA (presumably initiated from H 2 O) mixed with the triblock polymer.!2#"?!)-"#+"3/.(.+."+)!. Using the identical polymerization procedure,!"#-lactide (45.8 mg, 3.18 x 10-1 mmol), 1,3,4-triphenyl-4,5-dihydro-1H-1,2-triazol-5-ylidene (6.4 mg, 2.15 x 10-2 mmol) and "-caprolactam (2.8 mg, 2.48 x 10-2 mmol) were heated in 0.6 ml of dry benzene-$ % at 90VC for 22 hrs before _uenching with 5 drops 1M acetic acid. The resulting polymer, after precipitation in cold heptane and isolation, was analyzed by 300 MHz 1 H-NMR (CDCl 3 ): CLa moiety:! 2.41 (m, -CH 2 -), 2.18 (m, -CH 2 -), 1.18-0.98 (m, -(CH 2 ) 3 -)e PLA moiety: 5.04 (m, -CH-), 4.27 (_, -&8-OH), 1.5 (m, -CH 3 ). Table S1. Polymerization of Lactide from Amine and Alcohol Initiators. Entries Initiator [M] 0 /[I] 0 Polym. 1 Pyr-NH 2 a 2 PEO(NH 2 ) 2 b 3 PEO(NH 2 ) 4 c 4 PEO(OH) 2 c Time (h) Conv. (%) M nth (g.mol -1 ) M nnmr (g.mol -1 ) M nsec (g.mol -1 ) M w /M n 100 22.5 70 10022 8064 8549 1.07 86 71 79 13612 11605 9580 1.09 105 18 g100 19720 18099 19388 1.24 101 46 75 16902 14058 12874 1.17 5 "-Cla b 13 22 85 1984 1984 NA - a [LA] 0 R 0.82 M, [Pyr-NH 2 ] 0 /[1] 0 R 1. b [LA] 0 R 0.35 M, [PEO(NH 2 ) 2 ] 0 /[1] 0 R 0.25. c [LA] 0 R 1.31 M, [PEO(NH 2 ) 4 ] 0 /[1] 0 R 0.125. d [LA] 0 R 1.31 M, [PEO(OH) 2 ] 0 /[1] 0 R 1. e [LA] 0 R 0.35 M, ["-Cla] 0 /[1] 0 R 1. - 3 -
Figure S1. MALDI-TOF Mass spectra of poly(!"#-lactide) initated from 4-pyrenemethylamine ([LA] 0 R 1 M, [pyr-nh 2 ] 0 R 0.02M, [1] 0 R 0.02M, 68N conv, M n R 6,400 (GPC vs PS), M w ]M n R 1.06, degree of polymerization (a) entire spectra, (b) blowup of spectra. Calculated m]z for n(lactic acid repeat unit R 72) l pyrene amine l Na R 4791 (n R 63), 4862 (n R 64), 4935 (n R 65), 5007 (n R 66), 5079 (n R 67), 5152 (n R 68). - 4 -
M n GPC (g/mol) 15000 14000 13000 12000 11000 10000 9000 8000 7000 6000 5000 y = 100.71x + 5396.7 R 2 = 0.9499 0 20 40 60 80 100 Conv.(%) 1.5 1.45 1.4 1.35 1.3 1.25 1.2 1.15 1.1 1.05 1 Figure S2. Chart of Molecular weight (-#- GPC vs. Polystyrene) and M w ]M n (-o-) versus conversion for the polymerization of!"#-lactide initiated from PEO-(NH 2 ) 2 in C 6 D 6 at 90VC using 1 as catalyst. Conditions: [LA] 0 R 1M, [PEO] 0 R 1.99 x 10-2 M and [1] 0 R 3.99 x 10-2 M. PDI Figure S3. 300 MHz 1 H-NMR (CDCl 3 ) of PLA 2 -PEO-PLA 2 (= ( R 9,580e = C D= ( R 1.09). The numbers under the brackets indicate the integration of the designated peaks. See text for peak assignments. - 5 -
Figure S4. First-order plots for the!"#-lactide polymerization initiated with either PEO- (NH 2 ) 2 (upper) or PEO-(OH) 2 (lower) in C 6 D 6 at 90VC using triazolium carbene 1 as catalyst. Conditions: PEO-(NH 2 ) 2 polymerization: [LA] 0 R 1 M, [PEO] 0 R 1.99 x 10-2 M and [1] 0 R 3.99 x 10-2 Me PEO-(OH) 2 polymerization: [LA] 0 R 6.25 M, [PEO] 0 R 6.25 x 10-3 M and [1] 0 R 1.25 x 10-2 M. As noted in text, k E-NH2 ] k E-OH R 1.97, where k obs R k 1 [PEO][1], see ref. 6. 16 14 20703 Intensity 12 10 8 8926 6 4 25 30 35 40 Ret. Vol. (ml) Figure S5. Gel Permeation Chromatogram of lactide polymerization carried out with an e_uimolar mixture of PEO-(NH 2 ) 2 and PEO-(OH) 2 in C 6 D 6 at 90VC using triazolium - 6 -
carbene 1 as catalyst. Conditions: [LA] 0 R 1.16 M, [1] 0 R 1.0 x 10-2 M, PEO-(NH 2 ) 2, [PEO-(NH 2 ) 2 ] 0 R [PEO-(OH) 2 ] 0 R 1.72 x 10-3 M - 7 -