Sulfenylation of Ortho Esters. A Novel Preparation of 2-alkanoic Acids

Article abstract of DOI:10.1021/jo00151a004

Trifluoromethanesulfenyl chloride reacts readily with ortho esters of acetic acid as well as ortho esters of higher aliphatic carboxylic acids to yield 1,1,1-trialkoxy-2-<(trifluoromethyl)thio>alkanes 4a-c.In the presence of an excess of trifluoromethanesulfenyl chloride, disubstitution of triethyl orthoacetate was observed, giving 1,1,1-triethoxy-2,2-bis<(trifluoromethyl)thio>ethane (6), which underwent facile thermal elimination to yield 1,1-diethoxy-2,2-bis<(trifluoromethyl)thio>ethene (8).The trialkoxyethanes 4a-c are easily transformed into the corresponding <(trihalomethyl)thio>alkanoic acids and lower alkyl esters.Trichloromethanesulfenyl chloride, a less reactive sulfenyl halide, reacts at elevated temperature in a similar manner with trimethyl and triethyl orthoacetate to furnish 1,1,1-trialkoxy-2-<(trichloromethyl)thio>ethanes 10a and 10b.A radical chain mechanism is proposed for the formation of 10a and 10b.