SCOPE AND STEREOCHEMICAL COURSE OF THE (TRIMETHYLSILYL)CYCLOPENTENE ANNULATION

Article abstract of DOI:10.1016/S0040-4020(01)88592-6

A new, regiospecific <3+2> annulation approach to highly substituted 5-membered carbocycles has been developed.The "TMS-cyclopentene annulation" involves the reaction of (trimethylsilyl)allenes with electrondeficient alkenes and alkynes in the presence of titanium tetrachloride to afford, in a single step, a functionalized and highly substituted TMS-cyclopentene derivative.Annulations employing α, β-unsaturated ketones proceed stereoselectively via suprafacial addition to the enone.Some useful transformations of the annulation products are also described; for example, treatment with K2CO3-methanol or HF in acetonitrile effects isomerization and desilylation yielding α, β-unsaturated ketones.