AbstractThe selective conversion of natural or synthetic neral to (1R,6S)-trans-isopiperitenol would enable and expedite sustainable routes to menthol1,2 and cannabinoids3–5. However, this reaction has been considered impossible because its product is more reactive to the required acid catalysts than its starting material, resulting in several side products6–9. We now show that an unsymmetric, strong and confined chiral acid, a highly fluorinated imino-imidodiphosphate, catalyses this process with excellent efficiency and selectivity. Expanding the method to other α,β-unsaturated aldehydes could enable access to new cannabinoids and menthol derivatives not readily accessible previously. Mechanistic studies suggest that the confined catalyst accomplishes this reaction by binding the product in an unreactive conformation, thereby preventing its decomposition. We also show how (1R,6S)-trans-isopiperitenol can be readily converted to pharmaceutically useful cannabinoids and menthol, each in the shortest and most atom-economic routes so far.
摘要将天然或合成的矿物质选择性地转化为 (1R,6S)-反式-异哌啶烯醇,可以实现并加快薄荷醇1,2 和大麻素3-5 的可持续路线。然而,这一反应一直被认为是不可能的,因为其产物对所需酸催化剂的反应性比起始原料要强,会产生多种副产品6-9。现在,我们证明了一种不对称、强限制性手性酸(一种高度氟化的亚氨基-亚胺二磷酸酯)可以催化这一过程,并具有极佳的效率和选择性。将这种方法扩展到其他α、β-不饱和醛类,可以获得以前不容易获得的新大麻素和薄荷醇衍生物。机理研究表明,密闭催化剂是通过将产物束缚在非反应构象中,从而阻止其分解来完成这一反应的。我们还展示了 (1R,6S)-反式-异哌替苯酚如何以迄今为止最短和最经济的途径,轻易地转化为具有药用价值的大麻素和薄荷醇。