Divergent Functionalization of Alkynes Enabled by Organic Photoredox Catalysis

Abstract

Direct Functionalization of alkynes under oxidative is challenging, as alkynes are usually recalcitrant towards typical oxidants. Herein, we communicate a strategy for the divergent functionalization of alkynes with photoexcited acridinium organic dyes, presumably via the formation of vinyl cation radicals as key intermediates. Based on the nature of the nucleophiles, different types of difunctionalized products were obtained in moderate to good yields. Addition of lithium Lewis acids resulted in a surprising reversal of diastereocontrol.

Synthesis of Isoquinolines and Related Heterocycles under Visible-Light Conditions

“…To the best of our knowledge, such idea has not been reported so far and additionally, examples of cyclization of NCR on triple bonds are also rare and thus still represent an important challenge. 39,40 Therefore, we suggest utilizing dinitroaryloxime 37 derivatives to construct isoquinoline frameworks through the formation of an iminyl radical, 41 followed by intramolecular cyclization on a vicinal triple bond (Scheme 1). It is worth noting that the literature contains limited information on cyclization on alkynes using visible light compared to alkenes.…”

“…Moreover, examples of NCR remain scarce in the literature compared to C-centered radicals. To the best of our knowledge, such idea has not been reported so far and additionally, examples of cyclization of NCR on triple bonds are also rare and thus still represent an important challenge. , …”