Cascade Radical Cyclizations of Benzannulated Enyne−Allenes. Unusual Cleavage of a Benzene Ring Leading to Twisted 1,1‘-Dialkyl-9,9‘-bifluorenylidenes and Spiro[1<i>H</i>-cyclobut[<i>a</i>]indene-1,9‘-[9<i>H</i>]fluorenes]
作者:Yonghong Yang、Jeffrey L. Petersen、Kung K. Wang
DOI:10.1021/jo030147j
日期:2003.7.1
9'-[9H]fluorene] 20 apparently was produced via two intramolecular [2 + 2] cycloaddition reactions of the benzannulated enyne-allene moieties, generated in situfrom the benzannulated enediynyl propargylic alcohols. The twisted 1,1'-dimethyl-9,9'-bifluorenylidene 33 and the spiro[1H-cyclobut[a]indene-1,9'-[9H]fluorene] 39 (trans/cis = 3:1) were likewise produced from 32 and 38, respectively.