Oxetanes are an important structural motif found in a range of natural products and compounds of pharmaceutical interest. However, typical methods to make non-symmetrical oxetanes are lengthy and involve laborious functional group manipulation. Direct photochemical cycloaddition of aldehydes and alkenes (the Paternò–Büchi reaction) represents the most convergent synthetic method, but mechanistic limitations mean substrate scope is limited. We have explored the photochemistry of S-aryl thioformates as a possible general way to access 1,2-disubstituted oxetanes following reductive desulfurization to remove the necessary radical stabilization element, thereby accomplishing the unknown Paternò–Büchi formylation. Synthesis of a wide range of S-aryl thioformates with varying electronic properties was successful, and their reactivity under both direct UV irradiation and photoredox catalysis has been explored. In preliminary studies, a variety of products have been observed and isolated, including an interesting sulfoxide product. By understanding the photochemical mechanism leading to sulfoxide formation, we can synthesize it in good yields or eliminate it entirely. We will continue to explore the photochemical reactivity of S-aryl thioformates, with the ultimate goal of developing a new synthesis of oxetanes or discovering other novel reaction methodologies.

Photochemical reactions of S-aryl thioformates: Toward a synthesis of oxetanes via formal formylation

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.