Tris orthoformates, synthesi

The preparation of orthoformic acid esters from chloroform and alkali metal alkoxides is a long known procedure, " which can be performed under phase transfer catalysis. If small amounts of alcohol are present in the phase-catalyz process, cyclopropanes (372 Scheme 67) can be produced by aHHifinn of dichlorocarbene to l,2-dialkoxy-l,2-dichloroethylenes, which are thought to be intermediates. " Al-kenes of this kind, e.g. (373 equation 176), have been observed as byproducts in the synthesis of tri-r-butylorthoformate from chlorodifluoromethane or dichlorofluoromethane and potassium r-butoxide. Trimethoxyacetonitrile was prepared from trichloroacetonitrile and sodium methoxide. ... 

The dimethoxy-compound is obtained from the bromo-ketone (321) and tri-methyl orthoformate. This reaction sequence may prove useful for regiospecific synthesis of other enol ethers, where the bromo-ketones are available. 

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