Allylic lithium oxyanionic directed and facilitated simmons-smith cyclopropanation: stereoselective synthesis of (+/-)-cis-sabinene hydrate and a novel ring expansion.
[reaction: see text] The lithium salts of acid-sensitive allyl alcohols, which themselves decompose during Simmons-Smith cyclopropanation, undergo smooth cyclopropanation in the usual stereocontrolled manner. This concept is applied to the most efficient synthesis of (+/-)-cis-sabinene hydrate and to the cyclopropanation of the anion of a nonisolable allyl alcohol resulting upon workup in a ring-expanded enone. The cyclopropanations are also faster for the lithium salts than for the allyl alcohols themselves.
Cheng
D
D
Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA.
Kreethadumrongdat
T
T
Cohen
T
T