(E)-2-Oxo-1-sulfonyl-3-alkenes as Reactive Hetero 1, 3-Dienes. Absolutely endo-Selective Hetero Diels-Alder Reactions with Vinyl Ethers in the Presence of a Lewis …
E Wada, H Yasuoka, S Kanemasa
Index: Wada, Eiji; Yasuoka, Hiroshi; Kanemasa, Shuji Chemistry Letters, 1994 , # 1 p. 145 - 148
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Citation Number: 15
Abstract
(E)-2-Oxo-1-sulfonyl-3-alkenes as new hetero 1, 3-dienes undergo smooth hetero Diels- Alder reactions with vinyl ethers in the presence of Eu (fod) 3 or TiCl 2 (i-PrO) 2. The reactions are absolutely endo-selective producing 2, 4-cis-3, 4-dihydro-2H-pyrans in excellent yields, sufficient catalytic cycles being attained. The sulfonyl-stabilized carbanions derived from the cycloadducts are alkylated followed by reductive desulfonylation.
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