Eu(fod)3 and SnCl4-catalyzed heterocycloadditions of O-silyl enol ethers deriving from cyclic ketones

Gilles Dujardin (1) , Arnaud Martel (1) , Eric Brown (1)

1 Laboratoire de Synthèse Organique

O-t-Butyldimethylsilyl enol ethers deriving from simple cyclic ketones acted as efficient dienophiles in the Lewis acid-catalyzed heterocycloadditions with methyl benzylidenepyruvate 1. Good selectivities were observed with cyclohexanone derivatives. Using Eu(fod)3, the dienophile 2b led to the expected endo adduct 3b (93–97%). When using SnCl4, the major product (89–95%) was found to be the “abnormal” adduct 5b with a trans ring junction. High yield heterocycloadditions of O-t-butyldimethylsilyl enol ether 2b and 1 are related to good Lewis acid-dependent selectivities: using Eu(fod)3 led to the expected endo adduct 3b (93–97%), but using SnCl4, the major product (89–95%) was found to be the “abnormal” adduct 5b with a trans ring junction.

Domaines: Chimie organique

Gilles Dujardin, Arnaud Martel, Eric Brown. Eu(fod)3 and SnCl4-catalyzed heterocycloadditions of O-silyl enol ethers deriving from cyclic ketones. Tetrahedron Letters, 1998, 39 (47), pp.8647-8650. ⟨10.1016/S0040-4039(98)01969-8⟩. ⟨hal-02298891⟩