Inter- and Intramolecular Pathways for the Formation of Tetrahydrofurans from β-(Phosphatoxy)alkyl Radicals. Evidence for a Dissociative Mechanism
作者:David Crich、Xianhai Huang、Martin Newcomb
DOI:10.1021/jo991570o
日期:2000.1.1
mercaptan undergo nucleophilic substitution followed by 5-exo-trig radical ring closure leading to tetrahydrofurans in good yield and with high trans selectivity. beta-(Phosphatoxy)alkyl radicals obtained by intramolecular hydrogen 1,5-abstraction with an alkoxyl radical undergo nucleophilic displacement providing tetrahydrofurans. The ensemble of results, including the effects of leaving groups and substituents
在烯丙醇和叔丁基硫醇的存在下,由Barton PTOC酯光解产生的β-(磷酸)烷基进行亲核取代,然后进行5-exo-trig自由基闭环,从而以高收率和高反式选择性产生四氢呋喃。通过分子内氢1,5-氢氧基与烷氧基基团的吸收而获得的β-(磷酸基)烷基基团进行亲核取代,得到四氢呋喃。结果的整体,包括离去基团和取代基的作用,强烈支持这些自由基亲核取代反应的离解机理。