A facile and efficient thiol-free one-pot method for direct synthesis of sulfides and sulfoxides under green conditions without using any metal catalyst is reported. For this purpose, we used benzyl bromides as starting materials in the presence of potassium thioacetate (PTA) and Oxone® which are low-cost, and readily accessible chemicals. This method is highly compatible with a variety of functional groups and delivered a series of sulfides, bis-sulfides, and sulfoxides in good yields. The selective formation of sulfoxides over sulfones is discussed via a mechanism.

/pdf/one-pot-thiol-free-synthetic-approach-to-sulfides-and-1g2rl58j.pdf

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

Abstract With the instability and alternative reactive modes of alkyl sulfenyl chlorides making the synthesis of a broad range of alkyl allenyl sulfoxides via the [2,3]-sigmatropic rearrangement difficult, alternative sources of electrophilic sulfur were explored. Examination of various N-sulfanylimides revealed that thiosuccinimides are a viable sulfur source for the synthesis of alkyl allenyl sulfoxides via the [2,3]-sigmatropic rearrangement. With the optimized conditions of excess propargyl alcohol and potassium carbonate in chloroform at 50 °C, a variety of alkyl allenyl sulfoxides were synthesized in fair to good yields (21–73%, 21 examples). Additionally, butyn-1,4-diols can be selectively monofunctionalized with a large excess of diol and stoichiometric triethylamine in THF at room temperature to form 1-hydroxyalkyl allenyl sulfoxides (26–71%). These diols can also be bis-functionalized to form 2,3-disubstitued dienes (53–66%) via two separate [2,3]-sigmatropic rearrangements. The formation of alkyl allenyl sulfoxides was also found to be selective for less substitution at the propargyl position (3:1–100:0 ratio) as shown in direct competition experiments. Trimethylsilylethyl thiosuccinimides were among the highest yielding of the thioimides. The sulfenate chemistry of select allenyl sulfoxides can be successfully performed. Graphical Abstract

Adam B. Riddell

Papers

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