Oxazinanones as chiral auxiliaries: synthesis and evaluation in enolate alkylations and aldol reactions

被引：33

作者：

Davies, Stephen G. ^{[1
]}

Garner, A. Christopher ^{[1
]}

Roberts, Paul M. ^{[1
]}

Smith, Andrew D. ^{[1
]}

Sweet, Miles J. ^{[1
]}

Thomson, James E. ^{[1
]}

机构：

[1] Univ Oxford, Dept Organ Chem, Chem Res Lab, Oxford OX1 3TA, England

来源：

ORGANIC & BIOMOLECULAR CHEMISTRY | 2006年 / 4卷 / 14期

关键词：

D O I：

10.1039/b604073j

中图分类号：

O62 [有机化学];

学科分类号：

070303 ; 081704 ;

摘要：

Homochiral beta-amino esters ( prepared on multigram scale by lithium amide conjugate addition) are readily transformed into oxazinanones. N-Acyl derivatives of oxazinanones undergo stereoselective enolate alkylation reactions, with higher stereoselectivities observed for the enolate alkylation of (R)-N-propanoyl-4-iso-propyl-6,6-dimethyl-oxazinan-2-one than the corresponding Evans oxazolidin-2-one. A C(4)- iso-propyl stereodirecting group within the oxazinanone conveys higher stereoselectivity than the analogous C( 4)- phenyl substituent.gem-Dimethyl substitution at C( 6) within the oxazinanone framework facilitates exclusive exocyclic cleavage upon hydrolysis to furnish alpha-substituted carboxylic acid derivatives and the parent oxazinanone in good yield. Asymmetric aldol reactions of a range of aromatic and aliphatic aldehydes with the chlorotitanium enolate of ( R)- N-propanoyl-4-iso-propyl- 6,6-dimethyl-oxazinan-2-one proceed with excellent diastereoselectivity. Hydrolysis of the aldol products affords homochiral alpha-methyl-beta-hydroxy-carboxylic acids.

引用

页码：2753 / 2768

页数：16

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