N. Nanjundaswamy et al., Tetralone esters as intermediates for the synthesis of podophyllotoxin derivatives via cyclopropanation of chalcones, SYN COMMUN, 30(7), 2000, pp. 1179-1191
Cyclopropyl eater (8a-f) were synthesized by the cyclopropanation of chalco
nes (7a-e) in dry benzene using powdered sodium in 80-85% yield. Preparatio
n of tetralone ester (4a-e), an intermediate for the synthesis of podophyll
otoxin derivatives by Lewis acid (SnCl4) catalyzed cyclization of(8a-e) is
also described here.