Concise synthesis of cycloheptatrienes from aldehydes and the Wittig reagent prepared from pyruvic ester

A novel and concise synthesis of 1,3,5-cycloheptatrienes has been developed. The reaction of 4-substituted-4-pentenal derivatives with the Wittig reagent prepared from pyruvic ester under the optimal conditions proceeded to give 1,6-di- and 1,6,7-trisubstituted-1,3,5-cycloheptatrienes in moderate yield. The synthesis is advantageous through its use of readily available reagents, milder reaction conditions compared to those previously reported, and simple manipulations. Additionally, a plausible mechanism via intramolecular [4+2]cycloaddition followed by the ring-expansion of norcarene is proposed based on the products of the reaction. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

A novel and concise synthesis method for 1,3,5-cycloheptatrienes has been developed, which can be achieved through mild reaction conditions and simple manipulations. The synthesis is advantageous due to its use of readily available reagents and moderate yields of the desired products.