Reaction of 1-Chlorovinyl p-Tolyl Sulfoxides with Carbanion of Acetonitrile: A Novel Synthesis of Cyclopentanone Derivatives with Three Consecutive Carbon–Carbon Bond-Formations via the Enaminonitriles
作者:Tsuyoshi Satoh、Hiroyuki Ota
DOI:10.1016/s0040-4020(00)00187-3
日期:2000.7
Treatment of 1-chlorovinyl p-tolyl sulfoxides derived from ketones with cyanomethyllithium gave cyclopentadienyl enamino-nitriles in high yields with three consecutive carbon-carbon bond-formations. However, the 1-chlorovinyl p-tolyl sulfoxides derived from aldehydes did not give good results. The mechanism of this reaction and the reaction of the enaminonitriles to convert cyclopentanone derivatives were investigated. Several alpha-carbanion of nitriles other than acetonitrile added to the 1-chlorovinyl p-tolyl sulfoxides at low temperature in good yield; however, they did not cyclize upon warming to room temperature. (C) 2000 Elsevier Science Ltd. All rights reserved.
Claisen Rearrangement Based Methodology for the Spiroannulation of a Cyclopentane Ring. Formal Total Synthesis of (±)-Acorone and Isoacorones
作者:A Srikrishna、P Praveen Kumar
DOI:10.1016/s0040-4020(00)00743-2
日期:2000.10
A Claisen rearrangement based methodology for spiroannulation of a cyclopentane ring to cyclic precursors and its application in the formal total synthesis of acorones 1 is described. Thus, Claisen rearrangement of 2-cycloalkylideneethanols 12 with 2-methoxypropene and a catalytic amount of mercuric acetate generates 4,4-substituted hex-5-en-2-ones 13. Ozonolytic cleavage of the terminal olefin in the enones 13 and intramolecular aldol condensation of the resulting keto-aldehydes 14 furnishes the spiroannulated compounds 15. (C) 2000 Elsevier Science Ltd. All rights reserved.