| Abstract
| - We present here the reaction of diorganoyl dichalcogenides with terminal alkynes under catalyst-free conditions, by a one-pot procedure, to prepare bis- and tris-chalcogenide alkenes selectively,avoiding the previous preparation of chalcogen alkynes. The reaction proceeded cleanly under mildreaction conditions, and the addition of dichalcogenides to alkynes occurred stereoselectively togive exclusively the corresponding Z isomers. We observed that the selectivity control was governedby the effective participation of the hydroxyl group from propargyl alcohols. In addition, the bis-chalcogenide alkenes were exclusively obtained with propargyl alcohol having the acidic hydroxylgroup proton. Conversely, the alkynes with no potentially acidic hydroxyl group proton, at propargylpositons, gave exclusively the tris-chalcogenide alkenes.
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