Asymmetric α-Acetoxylation of Carboxylic Esters. Preliminary Communication

来自 EBSCO

阅读量:

43

作者:

W OppolzerP Dudfield

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摘要:

Using the readily accessible chiral auxiliaries 1–3 the sulfonamide-shielded O-silylated esters 5 underwent π-face-selective α-acetoxylation on successive treatment with Pb(OAc)4 and NEt3 HF to give after recrystallization α-acetoxy ester 6 in 55–67% yields and in 95–100% d.e. Starting from conjugated enoates addition of RCu and subsequent acetoxylation 10→11→12 yielded α,β-bifunctionalized esters 12 with >95% configurational control at both Cα and Cβ. Nondestructive removal of the auxiliary (6→7, 6→8 and 12→13) gave either α-hydroxycarboxylic acids or terminal α-glycols in high enantiomeric purity. The prepared glycols 8c and 13a are key intermediates for previously reported syntheses of the natural products 16 and 17, respectively.

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DOI:

10.1002/hlca.19850680127

被引量:

472

年份:

1985

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2010
被引量:57

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