An unprecedented stereoselective titanium-mediated dihydrodimerization of allyl ethers and allylamines

Abstract

3-Phenylallyl ether 17, 2,5-dihydrofuran (1) and N-acceptor-substituted 2,5-dihydropyrrols 4, 6, 8, 10, 12 upon treatment with cyclohexylmagnesium bromide in the presence of Ti(Oi-Pr), were found to undergo a diastereoselective dihydrodimerization affording 1,5-dienes, d,l-2,3-diethenylbutane-1,4-diol (51% yield) and d,l-2,3-diethenyl-1,4-bis(sulfonylamino)butanes (43-52%), respectively. In the presence of titanium bis(4R,5R)-taddolate, the dihydrodimerization of 1 proceeded with 35-38% chemical yield and up to 94% ee.