Structure of P-mangostin

period concentrated hydrochloric acid was added at a rate of 25 ml per hour. After cooling the reaction mixture was diluted with water and extracted with benzene. The benzene solution was washed with water, dried (Na2SO4), and concentrated in vnclro. Recrystallization of the residual solid from aqueous ethanol gave 17 g of 13 (60%) melting at 49.0-49.5" (reported (8) m.p. 49.1-49.3"); i.r.(Nujol): 3100, 1650, 990, 910 (-CH=CHz), 36002400, 1720-1700 cm-I (COOH); n.m.r.: 6 6.0-5.4 m ( l H ) , 5.2-4.7 m (2H), 2.5-1.1 m (24H).