Ring-Opening Polymerization and Transesterification Reactions
COMMUNICATIONS
3H, OCH3), 3.55 (s, 1H, CH); 5b d¼2.19 (s, 6H, NCH3), 3.21 (s,
6H, OCH3), 4.30 (s, 1H, CH); 4 d¼2.29 (s, 18H, NCH3), 3.22 (s,
1H, CH).
40, 234; B. Tao, M. M. C. Lo, G. C. Fu, J. Am. Chem.
Soc. 2001, 123, 353.
[3] A. Cordova, W. Notz, G. F. Zhong, J. M. Betancort, C. F.
Barbas, J. Am. Chem. Soc. 2002, 124, 1842; A. Cordova,
S. Watanabe, F. Tanaka, W. Notz, C. F. Barbas, J. Am.
Chem. Soc. 2002, 124, 1866.
Ring-Opening of Lactide in the Presence of CH3OD
[4] E. Vedejs, O. Daugulis, S. T. Diver, J. Org. Chem. 1996,
61, 430; E. Vedejs, E. Rozners, J. Am. Chem. Soc. 2001,
123, 2428; S. Qiao, G. C. Fu, J. Org. Chem. 1998, 63, 4168.
[5] G. C. Fu, Adv. Organometal. Chem. 2001, 47, 101; G. C.
Fu, Pure Appl. Chem. 2001, 73, 347; B. L. Hodous,
G. C. Fu, J. Am. Chem. Soc. 2002, 124, 1578.
[6] S. J. Miller, G. T. Copeland, N. Papaioannou, T. E. Horst-
mann, E. M. Ruel, J. Am. Chem. Soc. 1998, 120, 1629.
[7] D. J. Guerin, S. J. Miller, J. Am. Chem. Soc. 2002, 124,
2134.
Tris(dimethylamino)methane (4; 17.8 mg, 123 mmol) and l-lac-
tide (17.7 mg, 123 mmol) were dissolved in THF-d8 (300 mL)
and CH3OD (50 mL, 1.23 mmol) was added. After 10 min
1H NMR analysis revealed the formation of methyl lactate, a
trace amount of methyl dilactate, aminal ester 3b, amide acetal
5b, and dimethylamine. Integration of the methine protons of
3b and 5b relative to the corresponding methoxy protons re-
vealed approximately 75% and 60% deuterium incorporation
1
into 3b and 5b, respectively. H NMR (CDCl3, 300 MHz): d
(methyl lactate)¼1.28 (d, J¼7 Hz, 3H, CH3), 3.34 (q, J¼
¼
7 Hz, H, CH); d (methyl dilactate)¼1.35 (d, J 7 Hz, 3H,
[8] T. Kawabata, M. Nagato, K. Takasu, K. Fuji, J. Am.
Chem. Soc. 1997, 119, 3169.
[9] A. C. Spivey, A. Maddaford, D. P. Leese, A. J. Redgrave,
J. Chem. Soc. Perkin Trans. 1 2001, 1785.
CH3), 1.43 (d, J¼7.0 Hz, 3H, CH3), 4.22 (q, J¼7 Hz, 1H,
CH), 5.06 (q, J¼7 Hz, 1H, CH). The deuterium incorporation
was also confirmed by GC-MS.
[10] T. Oriyama, K. Imai, T. Sano, T. Hosoya, Tetrahedron
Lett. 1998, 39, 3529.
[11] E. Vedejs, X. H. Chen, J. Am. Chem. Soc. 1996, 118,
1809.
[12] R. Breslow, J. Am. Chem. Soc. 1958, 80, 3719; K. Mote-
sharei, D. C. Myles, J. Am. Chem. Soc. 1997, 119, 6674;
although thiazole carbenes have a tendency to dimerize,
Arduengo has recently reported a stable, sterically hin-
dered carbene [3-(2,6-diisopropylphenyl)thiazole-2-yli-
dene]; A. J. Arduengo, J. R. Goerlich, W. J. Marshall,
Liebigs Ann.-Recl. 1997, 365.
Thermolysis of Tris(dimethylamino)methane (4)
Tris(dimethylamino)methane (0.25 mL, 1.7 mmol) was meas-
ured into an NMR tube closed with a J-Young valve and heated
to 130 8C. The tube was placed under vacuum briefly every 10
minutes. After an hour, the remaining liquid (~30 mL) was dis-
solved in benzene-d6 (0.3 ml) and the 1H NMR spectrum was
1
recorded. Only 4 was observed. H NMR (C6D6, 300 MHz):
d¼2.32 (s, 18H, NCH3), 3.02 (s, 1H, CH).
[13] D. Enders, U. Kallfass, Angew. Chem. Int. Ed. 2002, 41,
1743.
Attempted Exchange Reaction between
Tris(dimethylamino)methane and Diethylamine
[14] M. S. Kerr, J. R. De Alaniz, T. Rovis, J. Am. Chem. Soc.
2002, 124, 10298.
Tris(dimethylamino)methane (42 mg, 0.29 mmol) and diethyl-
amine (41 mL 0.29 mmol) were measured into an NMR tube
[15] A. Kumar, R. A. Gross, Biomacromolecules 2000, 1, 133;
A. Kumar, R. A. Gross, J. Am. Chem. Soc. 2000, 122,
11767; S. Kobayashi, H. Uyama, S. Namekawa, H. Hay-
akawa, Macromolecules 1998, 31, 5655; L. Liu, R. Bre-
slow, J. Am. Chem. Soc. 2002, 124, 4978.
closed with
a J-Young valve, dissolved in benzene-d6
1
(0.3 mL) and heated up to 80 8C. After 30 min the H NMR
spectrum was recorded. Only the starting materials were ob-
served.
[16] F. Nederberg, E. F. Connor, T. Glausser, J. L. Hedrick,
Chem. Commun. 2001, 2066; F. Nederberg, E. F. Connor,
M. Moller, T. Glauser, J. L. Hedrick, Angew. Chem. Int.
Ed. 2001, 40, 2712.
Acknowledgements
[17] M. Myers, E. F. Connor, T. Glauser, A. Mock, G. Nyce,
J. L. Hedrick, J. Polym. Sci. Part A: Polym. Chem.
2002, 40, 844.
[18] E. F. Connor, G. W. Nyce, M. Myers, A. Mock, J. L. He-
drick, J. Am. Chem. Soc. 2002, 124, 914.
The authors acknowledge support through the NSF Center for
Polymer Interfaces and Macromolecular Assemblies (CPIMA:
NSF-DMR-0213618) and an NSF-GOALI grant (NSF-CHE-
0313993). We thank Purac for a generous donation of l-lactide.
[19] G. A. Grasa, R. M. Kissling, S. P. Nolan, Org. Lett. 2002,
4, 3583; G. W. Nyce, J. A. Lamboy, E. F. Connor, R. M.
Waymouth, J. L. Hedrick, Org. Lett. 2002, 4, 3587;
G. A. Grasa, T. Guveli, R. Singh, S. P. Nolan, J. Org.
Chem. 2003, 68, 2812; R. Singh, R. M. Kissling, M. A. Le-
tellier, S. P. Nolan, J. Org. Chem. 2004, 69, 209.
[20] M. S. Viciu, G. A. Grasa, S. P. Nolan, Organometallics
2001, 20, 3607; A. J. Arduengo, F. Davidson, H. V. R.
Dias, J. R. Goerlich, D. Khasnis, W. J. Marshall, T. K.
Prakasha, J. Am. Chem. Soc. 1997, 119, 12742; L. Jafar-
References and Notes
[1] K. A. Ahrendt, C. J. Borths, D. W. C. MacMillan, J. Am.
Chem. Soc. 2000, 122, 4243; W. S. Jen, J. J. M. Wiener,
D. W. C. MacMillan, J. Am. Chem. Soc. 2000, 122, 9874;
V. M. Dong, D. W. C. MacMillan, J. Am. Chem. Soc.
2001, 123, 2448.
[2] G. C. Fu, Acc. Chem. Res. 2000, 33, 412; S. Arai, S. Bel-
lemin-Laponnaz, G. C. Fu, Angew. Chem. Int. Ed. 2001,
Adv. Synth. Catal. 2004, 346, 1081–1086
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