1242
Y. Tanaka et al.
LETTER
(3) (a) Ugi, I. Angew. Chem., Int. Ed. Engl. 1962, 1, 8; Angew.
Chem. 1962, 74, 9. (b) Dömling, A.; Ugi, I. Angew. Chem.
Int. Ed. 2000, 39, 3168. (c) Suginome, M.; Ito, Y. In Science
of Synthesis, Vol. 19; Murahashi, S.-I., Ed.; Thieme:
Stuttgart, 2004, 445–530.
NR2
2
t
+
BuMe2SiOH
CO2Me
R1
R22NH
base
5
Ph2BOR
(4) Whaley, W. M.; Govindachari, T. R. Org. React. 1951, 6,
t
SiMe2 Bu
O
151.
NR2
(5) (a) Shafran, Y. M.; Bakulev, V. A.; Mokrushin, V. S. Russ.
Chem. Rev. 1989, 58, 148. (b) Royer, J.; Bonin, M.;
Micouin, L. Chem. Rev. 2004, 104, 2311.
OMe
2
–
Ph2B
base•H+
OR
A
OH
Ph2–B
OR
+NR2
R1
2
(6) (a) Bailey, C. D.; Houlden, C. E.; Bar, G. L. J.; Lloyd-Jones,
G. C.; Booker-Milburn, K. I. Chem. Commun. 2007, 2932.
(b) Gao, F.; Zhang, G.; Zhang, S.; Cheng, Y.; Shi, Z.; Li, Y.;
Gao, J. Tetrahedron 2007, 63, 3973. (c) Zhou, Z.; Xu, F.;
Han, X.; Zhou, J.; Shen, Q. Eur. J. Org. Chem. 2007, 5265.
(d) Bhattacharya, A. K.; Kaur, T. Synlett 2007, 745.
(e) Salter, M. M.; Kobayashi, J.; Shimizu, Y.; Kobayashi, S.
Org. Lett. 2006, 8, 3533. (f) Muraki, T.; Fujita, K.; Teraoka,
D. Synlett 2006, 2646. (g) Ella-Menye, J.-R.; Dobbs, W.;
Billet, M.; Klotz, P.; Mann, A. Tetrahedron Lett. 2005, 46,
1897.
H
O
C
D
R1
H
base
R2
2
O–
R1
– N
–
O
NR2
2
–
Ph2B
Ph2B
R1
base•H+
H
OR
H
OR
base•H+
B
C
(7) (a) Suginome, M.; Yamamoto, A.; Ito, Y. Chem. Commun.
2002, 1392. (b) Suginome, M.; Uehlin, L.; Yamamoto, A.;
Murakami, M. Org. Lett. 2004, 6, 1167.
Scheme 2 A proposed mechanism for the Ph2BOR-catalyzed Man-
nich-type reaction
(8) Suginome, M.; Uehlin, L.; Murakami, M. J. Am. Chem. Soc.
2004, 126, 13196.
Acknowledgment
(9) Suginome, M.; Tanaka, Y.; Hasui, T. Synlett 2006, 1047.
(10) Tanaka, Y.; Hasui, T.; Suginome, M. Org. Lett. 2007, 9,
4407.
(11) Suginome, M. Pure Appl. Chem. 2006, 78, 1377.
(12) Ishihara, K.; Yamamoto, H. Eur. J. Org. Chem. 1999, 527.
(13) General Procedure for the Ph2BOMe-Catalyzed
Mannich-Type Reaction
This work was supported by a Grant-in-Aid for Scientific Research
(No. 19205007) from the Ministry of Education, Culture, Sports,
Science, and Technology, Japan.
References and Notes
To a solution of Ph2BOMe (3.9 mg, 0.02 mmol) in DMSO
(1.0 mL) were added amine 3 (0.4 mmol), aldehyde 2 (0.4–
0.6 mmol), and ketene silyl acetal 4 (0.8 mmol). The mixture
was stirred for 12 h at 60 °C, quenched with ice water, and
extracted with EtOAc. The organic layer was washed with
H2O, and aqueous layer was extracted with EtOAc. The
combined organic layer was dried over Na2SO4 and
evaporated under vacuum. The crude 5 was purified by silica
gel column chromatography. The imine-containing products
8 and 10 could not be purified by column chromatography,
but were isolated by bulb-to-bulb distillation.
(1) (a) Kleinman, E. D. In Comprehensive Organic Synthesis,
Vol. 2.; Trost, B. M., Ed.; Pergamon: Oxford, 1991, 893.
(b) Arend, M.; Westermann, B.; Risch, N. Angew. Chem. Int.
Ed. 1998, 37, 1044.
(2) (a) Hutchins, R. O. In Comprehensive Organic Synthesis,
Vol. 8; Trost, B. M., Ed.; Pergamon: Oxford, 1991, 25.
(b) For recent examples, see: Baxter, E. W.; Reitz, A. B.
Org. React. 2002, 59, 1. (c) Tararov, V. I.; Kadyrov, R.;
Riermeier, T. H.; Börner, A. Chem. Commun. 2000, 1867.
(d) Apodaca, R.; Xiao, W. Org. Lett. 2001, 3, 1745.
(e) Basu, B.; Jha, S.; Bhuiyan, M. M. H.; Das, P. Synlett
2003, 555. (f) Gross, T.; Seayad, A. M.; Ahmad, M.; Beller,
M. Org. Lett. 2002, 4, 2055. (g) Miura, K.; Ootsuka, K.;
Suda, S.; Nishikori, H.; Hosomi, A. Synlett 2001, 1617.
(h) Shibata, I.; Suwa, T.; Sugiyama, E.; Baba, A. Synlett
1998, 1081.
(14) The imine–amine conjugate 7 exists as the cyclized aminal
form, which may be in equilibrium with the imine form
shown in the scheme.
Synlett 2008, No. 8, 1239–1242 © Thieme Stuttgart · New York