New Methodology for the Construction of Asymmetric Carbon Skeletons Utilizing the Chirality of Hetero Atoms

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a) The Diels-Alder reaction of various chiral sulfinyl eghenes under ultra-high pressure has been carried out. In most cases, the reaction with low reactive dienes such as furans afforded the cycloadducts in fairly high diastereoselectivity. Effective methodology for the construction of asymmetric carbon skeletons under atmospheric and ultra-high pressure is being developed.b) Asymmetric 1,3-dipolar cycloaddition of (RS)-sulfinylmaleate with various dipolarophiles has been studied and matched-pair concept has been proposed for the abtention of good diastereoselectivity. The maleate made a good combination with 2,3,4,5-tetrahydropyridine 1-oxide to give two cycloadducts with excellent diastereoselectivity.c) Synthesis of chiral sulfinylethenes which have a 2-exo-hydroxy-10-bornyl group as the sulfinyl ligand has been studied. These sulfinyl dienophiles effected Diels-Alder reactions with a high degree of diastereoselectivity. Especially, the chiral alfa-sulfinylmaleimides readily reacted with Diels-Alder dienes with rather low reactivities such as furan, to give the corresponding cycl oadducts under conventional conditions. Application of these asymmetric Diels-Alder reactions to the chiral synthesis of indolizidine- and pyrrolizidine-alkaloids has been accomplished.d) The new methodology for the preparation of optically active selenoxides using 2-exo-hydroxy-10-bornyl group as a chiral ligand has been developed. Application of the methodology for the preparation of novel chiral seleninyl dienophiles is under way.