Stereoselective functionalisation of SuperQuat enamides: asymmetric synthesis of homochiral 1,2-diols and α-benzyloxy carbonyl compounds

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作者：

C Aciro，SG Davies，AC Garner，Y Ishii，MS Key，KB Ling，RS Prasad，PM Roberts，H Rodriguez-Solla，Catherine O&#x;Leary-Steele

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摘要：

Homochiral ( E)- and ( Z)-enamides derived from SuperQuat ( S)-4-phenyl-5,5-dimethyl-oxazolidin-2-one undergo highly diastereoselective epoxidation upon treatment with dimethyldioxirane. Subsequent epoxide opening with meta-chlorobenzoic acid proceeds via a stereoselective S N1-type process, with retention of configuration, to give the corresponding 1′- m-chlorobenzoyl-2′-hydroxy derivatives. Treatment of the SuperQuat enamides with mCPBA effects this two-step transformation in one pot. Reductive cleavage of the isolated 1′- m-chlorobenzoyl-2′-hydroxy derivatives (≥96% de) generates homochiral 1,2-diols in ≥96% ee. Alternatively, regioselective lithiation of the enamide at C(1′) with tBuLi followed by reaction with an aromatic aldehyde and in situ O-benzylation generates a 1′-(benzyloxy-aryl-methyl) substituted enamide with high diastereoselectivity. Subsequent oxidative cleavage of the enamide C C bond with NaIO 4/RuCl 3 followed by methanolysis of the resultant N-acyl fragment furnishes an O-benzyl protected α-hydroxy methyl ester in high ee.

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关键词：

Asymmetric synthesis SuperQuat Enamides Oxidation 1,2-Diols

DOI：

10.1016/j.tet.2008.07.012

被引量：

101

年份：

2008