Synthesis of substituted thietanes and thiolanes from α- and β-chloroepoxides and their oxidation to 1,1-dioxides

Abstract

Treatment of 3-chloro-1-phenylpropylene oxide-1,2 (7) or 1-chloro-4-phenylbutylene oxide-3,4 (8) with H2S saturated ethanolic NaOEt gave 3-hydroxy-2-phenylthietane (9) and 3-hydroxy-2-phenylthiolane (10) respectively. A similar treatment of 3-chloro-2-phenylpropylene oxide-1,2 (12) at low temperatures gave 3-chloro-2-hydroxy-2-phenylpropanethiol (13); at reflux temperatures or by refluxing 13 in ethanolic NaOEt, 3-hydroxy-3-phenylthietane (14) was formed.Oxidation of 9, 10, and 14 with m-chloroperbenzoic acid or H2O2–HOAc gave the respective 1,1-dioxides 19, 20, and 25. The alcohols 19 and 20 were dehydrated to their corresponding cyclic olefins through the benzylsulfonate esters. Under the conditions of the Ritter reaction 25 dehydrated to the cyclic olefin. Treatment of 19 with mineral acid gave benzyl methyl ketone, while refluxing 19 in base gave benzyl methyl sulfone. Ethoxylation of 2-phenylthiete 1,1-dioxide (23) to the 3-ethoxy derivative 34 was achieved under basic conditions. Attempted chlorination of 9 resulted in desulfurization to 3-chloropropenylbenzene (5).