Highly Selective Thiiranation of 1,2-Allenyl Sulfones with Br2 and Na2S2O3: Mechanism and Asymmetric Synthesis of Alkylidenethiiranes

Link: ACIEE EarlyView

Chao Zhou (1), Chunling Fu (1),* Shengming Ma (1,2)*

(1)Laboratory of Molecular Recognition and Synthesis, Department of Chemistry, Zhejiang University, Hangzhou, 310027, Zhejiang, P.R. China

(2)Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Lu, Shanghai 200032, P.R. China

A method for thiirane synthesis from allene, using bromine and sodium thiosulfate. The reaction goes through a neat mechanism, via the isolated five-membered intermediate 5l for the formation of (E)-3l.

The reaction is also stereospecific as shown in Table 3.

The reaction was found to be widely applicable to a variety of substrates as shown in Table 2.

Finally, the reaction mechanism was proposed to be as shown in Scheme 2 - quite neat.