Pentatomic heteroaromatic cations. Part 10. A new route for the reduction of the functional group of carboxylic acids, acid chlorides, anhydrides, esters, nitriles, trihalogenomethyl compounds, aldehydes, and ketones to methyl or methylene groups

Abstract

The reactions of carboxylic acids, acid chlorides, anhydrides, esters, nitriles, and trichloromethyl and trifluoromethyl derivatives with benzene-1,2-dithiol in tetrafluoroboric acid–ether or boron trifluoride–ether, generally affords excellent yields of 2-substituted 1,3-benzodithiolylium tetrafluoroborates. These can be easily reduced with sodium borohydride to 2-substituted 1,3-benzodithioles, which by scission of the C(2)–S bond with sodium in liquid ammonia give the corresponding hydrocarbons. Also the carbonyl group of aldehydes and ketones can be reduced to the methylene group by related reactions.