Catalytic Enantioselective Synthesis of 2,6-Disubstituted Dihydropyrones by Hetero-Diels-Alder Reaction Using Chiral BINOL-Ti(IV) Complex

Abstract

Highly efficient enantioselective synthesis of optically active 2,6-disubstituted dihydropyrones was easily available by hetero-Diels-Alder reaction of aldehydes in presence of 20 mol% (R)-(+)-BINOL-Ti(IV) complex under mild reaction conditions. All reaction products were obtained in moderate to excellent yields (up to 99%) with high enantioselectivities (up to 99% ee).

Key words

hetero-Diels-Alder reaction - dihydropyrones - BINOL

References

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5

Compound 2 and 4 were also synthesized by us and applied to the hetero-Diels-Alder reaction of aldehydes promoted by BINOLs-Ti complexes. It was found that (R)-H₈-BINOL-Ti(IV) catalytic system could give better enantioselectivity and diastereoselectivity than (R)-BINOL-Ti(IV) complex.