... Page 10. 382 Vol. 36 (1988) 11-1 (2.50 g), 37'Z, formalin (6 ml) and HCOOH (6 ml) was stirred at 90—100 DC for 1h. After cooling, the mixture was made alkaline with aqueous K2C03 and extracted with AcOEt. The AcOEt layer was washed with water. ...