The versatility of alpha-chloropropargyl phenyl sulfide affords high stereo- and regioselectivities in indium-promoted coupling reactions under mild conditions.

Coupling reactions between alpha-chloropropargyl phenyl sulfide (11) and a series of aldehydes under aqueous conditions are reported. Not only is good stereoselectivity observed between syn and anti isomeric products, but excellent regioselectivity is also witnessed. In reactions using indium metal as a promoter, the propargyl functionality (12) is retained, unlike the use of more traditional metals that result in formation of products containing a mixture of both propargyl (12) and allene (13) moieties. The reaction is postulated to proceed via either a chelated or nonchelated route, controlled by the presence or absence of indium (III) chloride, and may be used to create synthetically useful building blocks. The formation of epoxyalkyne (14) molecules, which are found in many natural products and have wide use as synthetic templates, is presented as one example.