反应详情

A solution of 4a-methyl-4,4a,9,10-tetrahydro-2(3H)-phenanthrone 1 (7 g, 33 mmol; prepared by the method of A. L. Campbell and J. D. McChesney, Syn. Commun. 1979, 9, 471-479) is dissolved in anhydrous benzene (300 mL) and ethylene glycol (16 mL) and p-toluenesulfonic acid (0.7 g, 4 mmol) added. The solution is refluxed with the removal of water in a Dean-Stark trap according to the method of A. J. Vila, R. A. Spanevello, A. C. Olivieri, M. G. Sierra, and J. D. McChesney, Tet. Lett. 1989, 45, 4951-4960 to form the ketal, 2-ethylenedioxy-4a-methyl- 1,2,3,4,4a,9-hexahydrophenanthrene 2.

1. customprepared by the method of A