Enantioselective Synthesis of 2‑Arylbicyclo[1.1.0]butane Carboxylates

The rhodium-catalyzed reaction of 2-diazo-5-arylpent-4-enoates can be controlled by the appropriate choice of catalyst and catalyst loading to form either 2-arylbicyclo[1.1.0]butane carboxylates or cyclohexene derivatives. Both products are produced in a highly diastereoselective manner, with 2-arylbicyclo[1.1.0]butane carboxylates preferentially formed under low catalyst loadings. When the reaction is catalyzed by Rh2(R-BTPCP)4, the 2-arylbicyclo[1.1.0]butane carboxylates are generated with high levels of asymmetric induction (70–94% ee).铑催化的2-重氮-5-芳基-4-戊烯酸酯反应可通过选择合适的催化剂与催化剂负载量进行调控，选择性生成2-芳基双环[1.1.0]丁烷羧酸酯或环己烯衍生物。两种产物均以极高的非对映选择性方式生成，其中2-芳基双环[1.1.0]丁烷羧酸酯在低催化剂负载量条件下优先生成。当该反应以Rh2(R-BTPCP)4为催化剂时，所生成的2-芳基双环[1.1.0]丁烷羧酸酯具有优异的不对称诱导效果，对映体过量值（enantiomeric excess, ee）可达70%~94%。