An Enantioselective Approach to Furanoeremophilanes: (+)‑9‑Oxoeuryopsin

An
enantioselective total synthesis of the furanoeremophilane sesquiterpene
(+)-9-oxoeuryopsin 1 is reported. The synthesis involves
as a key step a copper­(II) triflate catalyzed tandem asymmetric conjugate
addition of AlMe3 to 2-methyl-2-cyclohexen-1-one with the
Feringa (S,R,R)-phosphoramidite
binaphthol ligand, followed by aldol condensation of the resulting
aluminum enolate with 4-methyl-3-furaldehyde 4. This
tandem transformation has not been previously reported with a 2-substituted-2-cyclohexen-1-one.
Conventional functional group manipulations completed the synthesis.

本研究报道了呋喃雅槛蓝烷型倍半萜（furanoeremophilane sesquiterpene）(+)-9-氧代优里普森1的对映选择性全合成（enantioselective total synthesis）。该合成的关键步骤为：以三氟甲磺酸铜(II)（copper(II) triflate）为催化剂，采用费林加（Feringa）(S,R,R)-亚磷酰胺联萘配体，实现三甲基铝(AlMe3)对2-甲基-2-环己烯-1-酮的串联不对称共轭加成（tandem asymmetric conjugate addition）；随后将生成的铝烯醇盐（aluminum enolate）与4-甲基-3-糠醛4进行羟醛缩合（aldol condensation）。目前尚未见以2-取代-2-环己烯-1-酮为底物的此类串联转化反应的相关报道。通过常规官能团转化（functional group manipulations）即可完成全合成。