The first example of the enantioselective ring opening of 1,2-epoxides by a ketone enolate is described. Using (R,R)-(salen)Cr(III)X (X=Cl, OTf) complexes 9 and 10 as the chiral Lewis acid (LA), the addition of the lithium enolate of acetophenone, 1, to cyclohexene oxide, 2, and cyclopentene oxide, 3, gave the corresponding gamma-hydroxy ketones (gamma-HKs) 4 and 5 in low to moderate yields and in up to 62-84% ee.
(Salen)Cr(III) complex-promoted asymmetric addition of lithium enolate of acetophenone to symmetrical 1,2-epoxides
CROTTI, PAOLO;DI BUSSOLO, VALERIA;FAVERO, LUCILLA;PINESCHI, MAURO
1997-01-01
Abstract
The first example of the enantioselective ring opening of 1,2-epoxides by a ketone enolate is described. Using (R,R)-(salen)Cr(III)X (X=Cl, OTf) complexes 9 and 10 as the chiral Lewis acid (LA), the addition of the lithium enolate of acetophenone, 1, to cyclohexene oxide, 2, and cyclopentene oxide, 3, gave the corresponding gamma-hydroxy ketones (gamma-HKs) 4 and 5 in low to moderate yields and in up to 62-84% ee.File in questo prodotto:
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