backbone of azaspiracid is outlined utilizing a key Julia coupling strategy. Spirocyclization of a C12 sulfone substrate induced formation of the unprecedented, nonnatural transoidal bisspiroketal. Construction of the bisspirocyclic array at C10 and C13, in the absence of the C12 sulfone, led to formation of the cisoidal orientation of the bisspirocycle, with the nonnatural stereochemistry at C13.
利用关键的Julia偶联策略概述了氮杂螺菌酸的C 1 -C 19碳主链的有效进入。C 12砜底物的螺旋环化诱导了空前的非天然的双螺旋双螺
缩酮的形成。在不存在C 12砜的情况下,在C 10和C 13处双螺环阵列的构建导致了双螺环的顺环体取向的形成,在C 13处具有非天然立体
化学。