Addition of organometallic reagents to acyloxathianes. Diastereoselectivity and mechanistic consideration
摘要:
The addition of methyl- and phenylmagnesium bromide and phenyllithium to 2-(methoxyacetyl)-, 2-[(tri-isopropylsiloxy)acetyl]-, and 2-[(methylthio)acetyl]hexahydro-4,4,7-trimethyl-4H-1,3-benxozathiin and the corresponding 2'-methyl, 2-(triisopropylsiloxy)propionyl, and 2-(methylthio)butyryl homologs has been Depending on the 2'-substituent, the reagent and (in case of the higher homologs) the configuration at C(2'), these reactions may or may not be highly diastereoselective and may or may not yield the product of Cram's chelate rule involving the oxygen moiety of the oxathiane ring. Explanations for the different stereochemical outcome of the various reactions are suggested.
Convenient synthesis of .alpha.-heterosubstituted acyloxathianes
摘要:
In contrast to simple esters, alpha-alkoxy, alpha-alkylthio, and alpha-dimethylamino esters react with lithiooxathiane 1-Li in good yield to give the corresponding alpha-functionalized 2-acetylhexahydro-4,4,7-trimethyl-4H-1,3-benzoxathiin 2. In some cases, mixtures of diastereomers (2, 2') are obtained. The reaction has been extended to alpha-methoxy- and alpha-[(triisopropylsilyl)oxy]propanoyl and alpha-(methylthio)butanoyl homologs which have chiral centers at C(alpha).
Convenient synthesis of .alpha.-heterosubstituted acyloxathianes
作者:Xu Bai、Ernest L. Eliel
DOI:10.1021/jo00045a031
日期:1992.9
In contrast to simple esters, alpha-alkoxy, alpha-alkylthio, and alpha-dimethylamino esters react with lithiooxathiane 1-Li in good yield to give the corresponding alpha-functionalized 2-acetylhexahydro-4,4,7-trimethyl-4H-1,3-benzoxathiin 2. In some cases, mixtures of diastereomers (2, 2') are obtained. The reaction has been extended to alpha-methoxy- and alpha-[(triisopropylsilyl)oxy]propanoyl and alpha-(methylthio)butanoyl homologs which have chiral centers at C(alpha).
Addition of organometallic reagents to acyloxathianes. Diastereoselectivity and mechanistic consideration
作者:Xu Bai、Ernest L. Eliel
DOI:10.1021/jo00045a032
日期:1992.9
The addition of methyl- and phenylmagnesium bromide and phenyllithium to 2-(methoxyacetyl)-, 2-[(tri-isopropylsiloxy)acetyl]-, and 2-[(methylthio)acetyl]hexahydro-4,4,7-trimethyl-4H-1,3-benxozathiin and the corresponding 2'-methyl, 2-(triisopropylsiloxy)propionyl, and 2-(methylthio)butyryl homologs has been Depending on the 2'-substituent, the reagent and (in case of the higher homologs) the configuration at C(2'), these reactions may or may not be highly diastereoselective and may or may not yield the product of Cram's chelate rule involving the oxygen moiety of the oxathiane ring. Explanations for the different stereochemical outcome of the various reactions are suggested.