Rhodium-Catalyzed Asymmetric [2 + 2 + 2] Cycloaddition of Unsymmetrical α,ω-Diynes with Acenaphthylene

It has been established that a cationic rhodium­(I)/(R)-BINAP complex catalyzes the asymmetric [2 + 2 + 2] cycloaddition of unsymmetrical α,ω-diynes with acenaphthylene at room temperature to give the corresponding chiral multicyclic compounds with high yields and ee values. Interestingly, enantioselectivity highly depended on the structures of α,ω-diynes used. The structural requirements of α,ω-diynes for high enantioselectivity were opposite to those in our previously reported cationic rhodium­(I)/(R)-Difluorphos complex-catalyzed asymmetric [2 + 2 + 2] cycloaddition of α,ω-diynes with indene.已有研究证实，阳离子铑(I)/(R)-联萘二苯膦（BINAP）配合物可在室温下催化不对称α,ω-二炔与苊烯的[2+2+2]环加成反应，以较高收率和对映体过量（ee）值得到对应的手性多环化合物。值得注意的是，该反应的对映选择性高度依赖于所使用的α,ω-二炔的结构。对于实现高对映选择性而言，α,ω-二炔的结构要求，与我们此前报道的阳离子铑(I)/(R)-二氟膦（Difluorphos）配合物催化的α,ω-二炔与茚的不对称[2+2+2]环加成反应中所要求的结构要求恰好相反。