Stereoselective construction of fused cyclopropane from ynamide and its application to synthesis of small drug candidate molecules

Herein, we report the development of an asymmetric intramolecular cyclopropanation reaction under silver catalysis. The strategy is based on diazo-free silver-carbene generation, providing gamma-lactam fused cyclopropane in an enantioenriched form. The ring system of the product is frequently encountered in bioactive molecules and pharmaceuticals. To highlight the utility of this method, the fused cyclopropane was converted into drug candidate molecules in short steps. In addition, computational investigations were performed to elucidate the reaction pathway. The computation based on density functional theory rationalized the experimentally observed chemoselectivity between the desired cyclopropanation and overoxidation process. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

An asymmetric intramolecular cyclopropanation reaction under silver catalysis has been developed, producing enantioenriched gamma-lactam fused cyclopropane commonly found in bioactive molecules and pharmaceuticals. The fused cyclopropane was efficiently converted into drug candidate molecules in short steps, highlighting the utility of this method. Computational investigations based on density functional theory clarified the chemoselectivity between the desired cyclopropanation and overoxidation process observed experimentally.