Synthesis and Resolution of Substituted [5]Carbohelicenes

Three types of racemic [5]­helicenyl acetates (1a, 2, and 3a) were synthesized. The synthesis of 2 was achieved by regioselective oxidation using o-iodoxybenzoic acid. The enzymatic kinetic resolution of 1a–3a was studied. The conversion with the highest rate and ee was obtained using 1a as the substrate and lipase Amano PS-IM as the enzyme. The two enantiomers of 1-[5]­helicenol 3b were separated using (1S)-10-camphorsulfonyl chloride as the chiral resolving agent.

本研究合成了三类外消旋[5]-螺烯乙酸酯（[5]-helicenyl acetates），涵盖1a、2及3a。化合物2的合成通过邻碘酰苯甲酸（o-iodoxybenzoic acid）介导的区域选择性氧化反应完成。针对1a~3a的酶法动力学拆分研究表明，以1a为底物、脂肪酶Amano PS-IM为催化酶时，反应转化率与对映体过量值（ee）均为最高。以(1S)-10-樟脑磺酰氯（(1S)-10-camphorsulfonyl chloride）为手性拆分剂，可分离得到1-[5]-螺烯醇3b的两种对映异构体。