1997 thiopyran derivatives

thiopyran derivativesR 0370

10 - 117Uncatalyzed (Thermal) and Lewis Acid-Promoted AsymmetricHetero-Diels- Alder Reaction of 1-Thiabuta-1,3-dienes (Thiochal-cones) with Di-(-)- menthyl Fumarate. Configuration Determinationby X-Ray Crystallographic Analysis of (2S,3R,4R)-(+)-2,3-Bis((-)-menthoxycarbonyl)-4,6-diphenyl-3,4-dihydro-2H-thiopyran and Con-version of Cycloadducts into Optically Pure Diols. — Asymmetrichetero-Diels-Alder reaction of 1-thia-1,3-butadienes, which are thermallygenerated from its dimers, with di-(-)-menthyl fumarate ( II) affords a mixtureof the 3,4-cis- and 3,4-trans-dihydrothiopyrans with good yields and fairdiastereoselectivities. An endo (3,4-cis): exo (3,4-trans) selectivity in theratio of 85:15-98:2 is obtained. — (SAITO, T.; FUJII, H.; HAYASHIBE, S.;MATSUSHITA, T.; KATO, H.; KOBAYASHI, K.; J. Chem. Soc., Perkin Trans.1 (1996) 15, 1897-1903; Dep. Chem., Fac. Sci., Sci. Univ. Tokyo, Shinjuku,Tokyo 162, Japan; EN)

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