Rapid Access to Arylated and Allylated CyclopropanesviaBr?nstedAcid-Catalyzed Dehydrative Coupling of Cyclopropylcarbinols

A regioselective protocol for the synthesis ofcyclopropyl derivatives that relies on Brookhart acid-catalyzeddehydrative coupling over substituted cyclopropylcarbinols withoutrearrangement is reported herein. The reactions proceed promptlyat 25 degrees C with only 2.0 mol % catalyst loading and produce thecyclopropyl derivatives in excellent yields. This method is welltolerated with a vast range of cyclopropylcarbinols includingaliphatic cyclopropylcarbinols, where no elimination product wasobtained, demonstrating the protocol's utility. Further, theHammett correlation suggested the formation of a cyclo-propylcarbinyl cation followed by a coupling reaction. Anextremely effective gram-scale reaction has also been demonstrated with a high turnover number.

Automated summary

A regioselective protocol for the synthesis of cyclopropyl derivatives via Brookhart acid-catalyzed dehydrative coupling without rearrangement is reported. The method shows excellent yield, tolerance towards various cyclopropylcarbinols, and an efficient gram-scale reaction with high turnover number.