9733
examined, and it was found that Ph SiH was very slow, Et SiH did not work and polymethyl-
2
2
3
hydrosiloxane was also very slow and incomplete.
(
dpm)2Mn
O
O
D
O
D
D
O
Me
3
Mn(dpm) /PhSiD3
Me
Me
Me
Me
Me
Me
Me
4
i-PrOH
4
4
4
D
11
12a
12b
12c
Me
Me
O
D
O
O
D
O
Mn(dpm) /PhSiD3
3
Me
Me
i-PrOH
O
Me
Me
4
Me
Me
1
2d
5
6
Scheme 1.
As expected from the results described in the accompanying paper, b,b-disubstituted a,b-
unsaturated ketones (and esters) are not conjugatively reduced using the above conditions.
Acknowledgements
The National Institutes of Health (GM 32718), The Robert A. Welch Foundation, Merck
Research Laboratories and Novartis are thanked for their support of this research.
References
1
2
. Magnus, P.; Payne, A. H.; Waring, M. J.; Scott, D. A.; Lynch, V. Tetrahedron Lett. 2000, 41, 9725.
. A number of methods have been reported in the literature to accomplish this transformation.
Conjugate reduction using Na(MeOCH CH O) AlH /CuBr: Semmelhack, M. F.; Stauffer, R. D.; Yamashita, A.
2
2
2
2
J. Org. Chem. 1977, 42, 3180. [(Ph P)CuH] : Mahoney, W. S.; Brestensky, D. M.; Stryker, J. M. J. Am. Chem. Soc.
3
6
1
988, 110, 291. [(Ph P)CuH] (cat)/n-Bu SnH or PhSiH : Lipshutz, B. H.; Keith, J.; Papa, P.; Vivian, R.
3 6 3 3
Tetrahedron Lett. 1998, 39, 4627. PhSiH /Mo(CO) (cat): Keinan, E.; Perez, D. J. Org. Chem. 1987, 52, 2576.
3
6
Interestingly, and in contrast, this latter reagent combination did not conjugatively reduce carvone (cf. entry 1).
Hydrosilylation of enones: Ojima, I.; Anagi, M. N.; Kogare, T.; Kumagai, M.; Horiuchi, S.; Nakatsugawa, K. J.
Organomet. Chem. 1975, 94, 449. FeꢀH based reagents: Noyori, R.; Umeda, I.; Ishigami, T. J. Org. Chem. 1972,
37, 1542. Cainelli, G.; Panunzio, M.; Umani-Ronchi, A. Tetrahedron Lett. 1973, 2491. Yamashita, M.; Watanabe,
Y.; Mitsudo, T.; Takegami, Y. Tetrahedron Lett. 1975, 1867. Collman, J. P.; Finke, R. G.; Matlock, P. L.;
Wahren, R.; Komoto, R. G.; Brauman, J. I. J. Am. Chem. Soc. 1978, 100, 1119. For a general review of conjugate
reductions: Comprehensive Organic Synthesis; Trost, B. M.; Fleming, I., Ed.; Pergamon Press, 1991; Vol. 8, p. 523.
. Zarghami, N. S.; Heinz, D. E. Phytochemistry 1971, 10, 2755. Hennig, M.; P u¨ ntener, K.; Scalone, M. Tetrahedron:
Asymmetry 2000, 11, 1849.
3
4
. Corriu, R. J. P.; Moreau, J. J. E. J. Organomet. Chem. 1976, 114, 135.
.