We report a rhodium-catalyzed asymmetric formal intermolecular [4 + 2] cycloaddition reaction of 2-alkylenecyclobutanols with α,β-unsaturated cyclic ketones leading to synthetically useful trans-bicyclic molecules. Three consecutive stereogenic centers are formed in a highly enantio- and diastereoselective manner. Stepwise C–C bond cleavage and annulation are likely involved in the reaction pathway. Here, iPr-Duphos is the viable chiral ligand that promotes excellent enantio-control.

中文翻译：

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铑(i)催化的2-亚烷基环丁醇与环烯酮通过C-C键断裂的不对称[4 + 2]环加成反应：有效获得反式双环化合物†

我们报道了2-亚烷基环丁醇与α,β-不饱和环酮的铑催化不对称形式分子间[4 + 2]环加成反应，产生合成有用的反式双环分子。三个连续的立体中心以高度对映体和非对映体选择性的方式形成。该反应途径可能涉及逐步的 C-C 键断裂和环化。在此，iPr-Duphos 是可行的手性配体，可促进出色的对映体控制。