1-Chlorovinyl
p-tolyl sulfoxides, including optically active form, were easily synthesized from carbonyl compounds and chloromethyl
p-tolyl sulfoxide in high overall yields. Treatment of the 1-chlorovinyl
p-tolyl sulfoxides with cyanomethyllithium gave cyclopentadienyl enaminonitriles in high yields with three consecutive C-C bond-formation. By this method 4, 4-disubstituted 2-cyclopentenones, including optically active form, were synthesized. Asymmetric synthesis of (+) -α-cuparenone was realized by using this method. When cyclic ketones were used in this method, spiro [4.n] alkenones were synthesized in high overall yields. Starting from cyclobutanones, a new synthesis of bicyclo [3.3.0] oct-1-en-3-ones was realized. A new route to fully substituted cyanoallenes was also developed. Reaction of the vinylsulfoxides with
N-lithio arylamines was found to give aminoaldehydes, from which α-quaternary α-amino acid derivatives were synthesized. Conjugate addition of lithium ester enolates and lithium amide enolates gave the adducts in high yields with very high 1, 2-, 1, 3- and 1, 4-asymmetric induction from the sulfur chiral center. A new synthesis of optically active carboxylic acids and γ-lactones having a tertiary or a quaternary carbon stereogenic center was realized. A novel method for asymmetric synthesis of both enantiomers of α-substituted carboxylic acid derivatives was also developed by this synthetic method.
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