Synthesis of 4-hydroxy-2-cyclopentenone derivatives by [3+2] annulation ofbeta-heteroatom-substituted acryloylsilanes and lithium enolate of methyl ketones

The [3 + 2] annulation using beta-[2-(pyridyl)thio] and beta,beta-dichloro derivatives of acryloylsilane and the lithium enolate of methyl ketones suc cessfully proceeded to afford 4-alkyl-4-hydroxy-3-(2-pyridylthio)cyclopenta none and 4-alkyl-3-chloro-4-hydroxy-2-cyclopentenone, respectively.