1-chlorovinyl P-tolyl Sulfoxides Research Articles

Asymmetric synthesis of 4,4-disubstituted 2-cyclopentenones from optically active 1-chlorovinyl p-tolyl sulfoxides and cyanomethyllithium with formation of a quaternary chiral center

Treatment of optically active 1-chlorovinyl p-tolyl sulfoxides having two different substituents at the 2-position, which were synthesized from unsymmetrical ketones and ( R)-(−)-chloromethyl p-tolyl sulfoxide in three steps, with cyanomethyllithium gave optically active 2-amino-1-cyano-5,5-disubstituted-1,3-cyclopentadienes with very high asymmetric induction from the sulfoxide chiral center. The products were converted to the enantiomerically pure 4,4-disubstituted 2-cyclopentenones by heating with phosphoric acid in acetic acid.

ChemInform Abstract: 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.

Abstract Treatment of 1-chlorovinyl p-tolyl sulfoxides derived from ketones with cyanomethyllithium gave cyclopentadienyl enaminonitriles 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 α-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.

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

Treatment of 1-chlorovinyl p-tolyl sulfoxides derived from ketones with cyanomethyllithium gave cyclopentadienyl enaminonitriles 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 α-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.