Competitive 3+2 and 2+2 cycloadditions of ester stabilized azaallyl anions to benzynes. Ring expansion of initial 3+2 products to isoquinolin-3-ones
作者:Helmi Hussain、Ebrahim Kianmehr、Tony Durst
DOI:10.1016/s0040-4039(01)00130-7
日期:2001.3
Reaction of the azaallyllithiums derived from imines of α-amino esters with benzynes results in the formation of 1,3-dihydroisoindoles and 4-hydroxyisoquinolines via 3+2 and 2+2 cycloadditions, respectively. The initially formed 1-carboethoxy-1,3-dihydroisoindoles rearrange under basic reaction conditions to form 3-(2H)-isoquinolinones.
A new route of preparing 1,4-dihydro-3(2)-isoquinolinones and 5,6,7,8-tetrahydrolsoquinolinones was developed by the hydrogenation of 3(2)-isoquinolinones. The 1,4-dihydro compounds -, were also prepared by synthesis, when the - ratio significantly differed from that of the products obtained by hydrogenation. Relative configurations and site of conformational equilibria were established by n.O.e. difference