A flexible approach for the asymmetric syntheses of hyacinthacines A2, A3 and structural confirmation of hyacinthacine A3
作者:Wen-Jun Liu、Jian-Liang Ye、Pei-Qiang Huang
DOI:10.1039/b926741g
日期:——
A concise and flexible approach for the asymmetric syntheses of polyhydroxylated pyrrolizidine alkaloids hyacinthacines A2 and A3 has been developed using iterative reductive alkylation of O,O′-dibenzyltartarimide (5) as key steps. The ambiguity about the structure of synthetic hyacinthacine A3 due to the differences in the NMR data of the synthetic material (2) and the natural product (hyacinthacine A3) was eliminated jointly by comprehensive 1D and 2D-NMR studies, and by analysis of the 1H and 13C NMR spectra of a mixed synthetic product and natural hyacinthacine A3. The latter method also allowed a confirmation of the structure of the natural hyacinthacine A3, and may be useful for structural confirmation of other hydroxylated alkaloids.
一种简洁灵活的方法已被开发,用于不对称合成多羟基吡咯里啶生物碱海葱碱A2和A3,关键步骤是对O,O′-二苄基酒石酰亚胺(5)进行迭代还原烷基化。由于合成材料(2)和天然产品(海葱碱A3)在核磁共振(NMR)数据上的差异,合成海葱碱A3的结构存在歧义,通过综合的1D和2D-NMR研究以及对合成混合产物和天然海葱碱A3的1H和13C NMR光谱分析,消除了这一歧义。后者方法还确认了天然海葱碱A3的结构,并可能对其他羟基化生物碱的结构确认有用。