Concise access to N9-mono-, N2-mono- and N2,N9-di-substituted guanines via efficient Mitsunobu reactions
作者:Steven Fletcher、Vijay M. Shahani、Alan J. Lough、Patrick T. Gunning
DOI:10.1016/j.tet.2010.03.118
日期:2010.6
Guanine poses several problems to the synthetic chemist owing to its polyfunctional nature and poor solubility. Over the past few decades, synthetic guanines have found applications as anti-cancer and anti-viral agents. Coupled with the ever-growing interest in designer PNAs and G-quartets, simple and efficient synthetic routes to novel guanines would be of significant benefit. We herein report that, upon simple protection and/or activation step(s), the guanine precursor 2-amino-6-chloropurine is rendered an excellent substrate for Mitsunobu chemistry, furnishing, after subsequent hydrolytic dechlorination and appropriate deprotection step(s), the desired N9-mono-, N2-mono- or N2,N9-di-substituted guanines in excellent yields (>= 80%). Importantly, we demonstrate that N9-functionalization proceeds with very good N9/N7 regioselectivity and with complete inversion of stereochemistry. (C) 2010 Elsevier Ltd. All rights reserved.