Functionalization toward total synthesis of the hallucinogenic neoclerodane diterpenoid salvinorin A was accomplished via three double sequences: bis-enol triflate synthesis, palladium-catalyzeddoublecarbonylation to the bis-enol triflate, and samarium diiodide-mediated double conjugate reduction. The configuration at C-12 was controlled by chelation-controlled diastereoselective reduction.
Elaboration of the Wieland-Miescher ketone through γ-hydroxylation, hydrogenation of the enone double bond and cyanohydrin formation, elimination and reduction of the nitrile led to an allyl alcohol. A Johnson-Claisen rearrangement gave rise to an advanced core structure of salvinorin A (53 %) and a diastereomer (20 %). It seems that the facial selectivity in the rearrangement is governed by steric
通过γ-羟基化、烯酮双键氢化和氰醇形成、消除和还原腈来精制维兰德-米歇尔酮,得到烯丙醇。 Johnson-Claisen 重排产生了 Salvinorin A (53%) 和非对映异构体 (20%) 的先进核心结构。重排中的面部选择性似乎受到空间和立体电子效应的控制。