Synthesis of carba-analogues of myoseverin by regioselective cross-coupling reactions of 2,6-dichloro-9-isopropylpurine
作者:Michal Hocek、Ivan Votruba、Hana Dvořáková
DOI:10.1016/s0040-4020(02)01586-7
日期:2003.1
A series of 9-isopropylpurine derivatives bearing 4-methoxyphenyl, 4-methoxybenzyl, (4-methoxyphenyl)ethynyl and 2-(4-methoxyphenyl)ethyl groups in positions 2 and 6 were prepared as carba-analogues of antimitotic myoseverin. Cross-coupling reactions of 2,6-dichloro-9-isopropylpurine (1) with one equivalent of (4-methoxyphenyl)boronic acid or (4-methoxybenzyl)zinc chloride gave regioselectively the 6-substituted 2-chloropurines which were used for another cross-coupling reaction with a second equivalent of the organometallic reagent. The Sonogashira reaction of 1 with 4-(methoxyphenyl)ethyne gave 2,6-bis[(4-methoxyphenyl)ethynyl]-9-isopropylpurine that was hydrogenated to 2,6-bis[2-(4-methoxyphenyl)ethyl]-9-isopropylpurine. Regioselectivity of the couplings was proved by means of H-1-N-15 HMBC experiments. 2,6-Bis[(4-methoxyphenyl)ethynyl]-9-isopropylpurine showed considerable cytostatic activity, while the other compounds were inactive. (C) 2003 Elsevier Science Ltd. All rights reserved.