Tetrahedron

Exclusively endo-selective lewis acid-vatalyzed hetero diels-alder reactions of (E)-1-phenylsuifonyl-3-alken-2-ones with vinyl ethers

E Wada, W Pei, H Yasuoka, U Chin, S Kanemasa

Index: Wada, Eiji; Pei, Wen; Yasuoka, Hiroshi; Chin, Uchou; Kanemasa, Shuji Tetrahedron, 1996 , vol. 52, # 4 p. 1205 - 1220

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Citation Number: 48

Abstract

(E)-1-Phenylsulfonyl-3-alken-2-ones as new hetero 1, 3-dienes undergo smooth hereto Diels-Alder reactions with vinyl ethers in the presence of a catalytic amount of Lewis acid such as ZnI2, Eu (fod) 3, and TiCl2 (i-PrO) 2. The reactions are absolutely endo-selective producing 2, 4-cis-3, 4-dihydro-2H-pyrans in excellent yields, the configuration at 3-position depending upon the stereochemistry of the starting vinyl ethers. Reductive ring opening ...