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New and Stereoselective Synthesis of 1,4-Disubstituted Buten-4-ols (Homoallylic Alcohol α-Adducts) from the Corresponding γ-Isomers (3,4-Disubstituted Buten-4-ols) via an Acid-Catalyzed Allyl-Transfer Reaction with Aldehydes

2000; American Chemical Society; Volume: 122; Issue: 7 Linguagem: Inglês

10.1021/ja990057p

1943-2984

Shin‐ichi Sumida, Masanori Ohga, Junji Mitani, Junzo Nokami,

Analytical Chemistry and Chromatography

The γ-adducts of homoallylic alcohols 3, derived from aldehydes via the usual reaction with common allylic metals 1, were converted to the corresponding α-adducts 6 by an acid-catalyzed allyl-transfer reaction. In the allyl-transfer reaction, anti- and syn-γ-adducts 3 gave E- and Z-α-adducts 6, respectively, and the optical purity of the γ-adducts 3 was transferred to the α-adducts 6 with >98%ee. This suggests that the allyl-transfer reaction proceeds stereoselectively via six-membered cyclic transition states [T]. The reaction was catalyzed by various metal triflates as well as Lewis acids and Brønsted acids.