[reaction: see text]. The influence of various Lewis acids in the radical cyclization of beta-allyloxyalkyl phenyl selenides was investigated. Whereas the unperturbed cyclization afforded trans-2,4-disubstituted tetrahydrofurans as the major products (cis/trans approximately 1/4.5), cyclization in the presence of trialkylaluminums (3 equiv) afforded predominantly (cis/trans approximately 7/1) the corresponding
[反应:请参见文字]。研究了各种
路易斯酸对β-烯丙氧基烷基苯基
硒化物自由基环化的影响。不受干扰的环化反应以反式2,4-二取代的
四氢呋喃为主要产物(顺式/反式约为1 / 4.5),而在三烷基铝(3当量)存在下环化则主要提供(顺式/反式约为7/1)相应的顺式异构体。