(3) by a sequence of 11 operations in overall yields of 14% and 2.4%, respectively. The key step 6 8(Scheme 2) involves a transient nitrone 7 which undergoes a regio- and stereoselective intramolecular cycloaddition to a 1,2-disubstituted olefinic bond.
外消旋
生物碱chanoclavine I(1)和isochanoclavine I(2)是通过
吲哚-4-
甲醛(3)的11种操作立体选择性合成的,总收率分别为14%和2.4%。关键步骤6 8 (方案2)涉及瞬态硝酮7,其对1,2-二取代的烯烃键进行区域和立体选择性分子内环加成。