Ring contraction reactions of 2-O-methanesulfonates of α-hydroxy-γ-lactones in aqueous medium to oxetane-2-carboxylic acids: A convenient synthesis of 3′-O-methyloxetanocin and a formal synthesis of oxetanocin
作者:Anil K. Saksena、Ashit K. Ganguly、Viyyoor M. Girijavallabhan、Russell E. Pike、Yao-Tsung Chen、Mohindar S. Puar
DOI:10.1016/0040-4039(93)88027-g
日期:1992.12
thiohydroxamic ester 17 directly provided the key oxetanosyl-thiopyridyl glycosides 18 which were successfully coupled to N-benzoyladenine. A two-step ring contraction of the tosylate 7 to the oxetane-2-carboxamide 23 is described. Attempted ring contraction of the triflate 24 gave the unexpected products 25 and 26. A ring expansion reaction (e.g. 14a → 21a) was also observed.
硫代异羟肟酸酯17的Barton脱羧重排15直接提供了关键的氧杂环糖基-硫代吡啶基糖苷18,它们成功地与N-苯甲酰腺嘌呤偶联。描述了甲苯磺酸酯7到氧杂环丁烷-2-羧酰胺23的两步环收缩。尝试的三氟甲磺酸酯24的环收缩产生了意想不到的产物25和26。还观察到环膨胀反应(例如14a → 21a)。