Preparation of both enantiomers of 1-allyl-1,2,3,4-tetrahydro-β-carboline using allyltin reagents and a chiral auxiliary derived from l-proline
作者:Takashi Itoh、Yûji Matsuya、Yasuko Enomoto、Akio Ohsawa
DOI:10.1016/s0040-4020(01)00684-6
日期:2001.8
beta -Carboline, which had an acyl group derived from L-proline at the 9-position, reacted with allyltributyltin and 2,2,2-trichloroethyl chloroformate, to afford an 1-allyl-1,2-dihydro-beta -carboline derivative in a diastereo selective manner. The chiral acyl group at N-9 was readily eliminated by aqueous alkali to give a corresponding carboxylic acid. The formed 1-allyl-1,2-dihydro-beta -carboline was transformed via two reduction steps to 1-alkyl-1,2,3,4-tetrahydro-beta -carboline in high ee. When the allylation was carried out using tetraallyltin instead of allyltributyltin, the stereoselectivity was reversed, and the antipode of the allyl adduct was obtained in high yield and ee in the presence of tin(IV) tetraiodide. Thus, it was found that both enantiomers of 1-allyl-beta -carboline were obtained in good enantioselectivities by the use of the same chiral auxiliary. (C) 2001 Elsevier Science Ltd. All rights reserved.