N‐Sulfanylimides as the Sulfur Source for Alkyl Allenyl Sulfoxides via [2,3]‐Sigmatropic Rearrangement

Abstract

Sulfenyl chlorides are a reliable starting material to access allenyl sulfoxides with aryl or haloalkyl groups by way of sulfenate ester formation followed by [2,3]-sigmatropic rearrangement. Application of the chemistry of alkanesulfenyl chlorides is much less common due to competing fates along the reaction pathway. In this paper, N-sulfanylsuccimides (thiosuccinimides) are shown to be a viable replacement for sulfenyl chlorides. A number of allenyl alkyl sulfoxides are prepared in fair to good yields (21-73 %, 21 examples). In addition, some butyn-1,4-diols can be selectively monofunctionalized to form allenyl sulfoxides (26-71 %) with a hydroxyalkyl group geminal to the sulfur. Butynediols also permit synthetic access to dienes via successive sulfenate ester formation and [2,3]-sigmatropic rearrangement reactions. N-2-Trimethylsilylethylthosucinimides were among the highest yielding of the thioimides.

One-pot thiol-free synthetic approach to sulfides, and sulfoxides selectively

“… 32 However, sulfoxide allenyl derivatives are quite limited and were prepared via a multi-step synthetic protocol. 33 With this methodology, they are prepared quite easily. Allenyl sulfoxides were observed when the propargyl bromides were used as electrophiles.…”

“…Based on the mechanism as previously reported, we suggest that the formation of sulfur bromo bond is a key factor to reduce the reactivity of sulfur atom thus inhibiting further oxidation. 34 Because of this bond formation, only one oxygen atom can be attached to the sulfur atom and hence the formation of the sulfoxides (26)(27)(28)(29)(30)(31)(32)(33) predominates in a one-pot reaction.…”