Reactions of Carbonyl Compounds with diisobutyltelluronium Bromide Mediated by Different Strong Bases: Highly Regioselective Synthesis of (Trimethylsilyl)propargyl Alcohol and Highly Stereoselective Synthesis of cis-(Trimethylsilyl)alkynyl Epoxides

Article abstract of DOI:10.1021/jo00050a042

<(Trimethylsilyl)propargyl>diisobutyltelluronium bromide (1), after being treated with alkyl- or aryllithium reagent, undergoes a lithium-tellurium exchange reaction via an unstable transient tetraorganyltellurium intermediate, and the in situ generated lithium species react with carbonyl compounds to give (trimethylsilyl)propargyl alcohols 2 in high yields with high regioselectivity.However, when the telluronium salt 1 was treated with nonnucleophilic bases such as LDA or lithium 2,2,6,6-tetramethylpiperidide, the moderately stabilized silylated telluronium ylide formed.The silylated telluronium ylide reacted with carbonyl compounds to afford (trimethylsilyl)alkynyl epoxides 11 in good to excellent yields with high cis stereoselectivity.