Aryl azide-allene cycloaddition. The contrasting behavior of two simple allenes, 1,2-cyclononadiene and 1,2-propadiene
作者:Donald K. Wedegaertner、Rangin K. Kattak、Isom Harrison、Sharon K. Cristie
DOI:10.1021/jo00014a026
日期:1991.7
1,2-Cyclononadiene (1) reacts with phenyl azide (2a) and 4-bromophenyl azide (2b) to give conjugated triazoline adducts 3a and 3b, respectively. (R)-(+)-1 and 2a react to give (S)-(+)-3a, which is consistent with a concerted cycloaddition mechanism. The reaction of 1,2-propadiene (6) and 2a gives triazoles 8 and 10 plus compound 18 in nearly equal amounts. The formation of these products is rationalized by a scheme involving initial formation of triazolines 7 and 9. Triazoline 3a is slowly isomerized by sodium ethoxide or N,N-dimethylaniline to triazole 20.