反应详情

FIG. 2 illustrates four additional embodiments (methods A-D) for preparing the 1,3-oxathiolane ring. As a nonlimiting illustrative example of method A in FIG. 2, (5-oxo-1,3-oxathiolan-2-yl)methyl butanoate can be prepared by a four-step process which does not require purification of the intermediate products. In a first step, (2,2-dimethyl-1,3-dioxolan-4-yl)methyl butanoate is prepared from solketal and n-butyryl chloride in t-butyl methyl ether, DMAP and triethylamine. The (2,2-dimethyl-1,3-dioxolan-4-yl)methyl butanoate is then placed in solution with Dowex 50W X8-100 H+ resin in methanol, to yield 2,3-dihydroxypropyl butanoate. The resulting diol is then reacted with a solution of sodium periodate in distilled water to produce 2-oxoethyl butanoate. Using 2-oxoethyl butanoate, the (5-oxo-1,3-oxathiolan-2-yl)methyl butanoate can be prepared by reaction with mercaptoacetic acid as p-TsOH.H2O in acetonitrile. The (5-oxo-1,3-oxathiolan-2-yl)methyl butanoate can be converted into its 5-acetyloxy derivative by reacting with lithium tri-t-butoxy aluminum hydride in THF.

1. customfor preparing the 1,3-oxathiolane ring
2. custompurification of the intermediate products
3. customIn a first step, (2,2-dimethyl-1,3-dioxolan-4-yl)methyl butanoate is prepared from solketal and n-butyryl chloride in t-butyl methyl ether, DMAP and triethylamine