Ruthenium-Catalyzed Interrupted Transfer Hydrogenation: An Approach for Reductive Functionalization of Quinolinium and Napthyridinium Salts

• Published in: Journal of organic chemistry Vol. 89; no. 18; pp. 13167 - 13178
• Main Authors: Dethe, Dattatraya H., Singh, Prabhakar, Joshi, Asha, Biswas, Proshanta
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 20.09.2024; Amer Chemical Soc
• Subjects: catalytic activity; Chemistry; Chemistry, Organic; feedstocks; heterocyclic compounds; hydrides; hydrogen; hydrogenation; Lewis acids; organic chemistry; Physical Sciences; ruthenium; Science & Technology; METHANOL; DEAROMATIZATION
• ISSN: 0022-3263; 1520-6904; 1520-6904
• DOI: 10.1021/acs.joc.4c01289

Until now, a myriad of effective approaches have emerged for the functionalization of N-heteroaryl C–H bonds. In contrast, dearomatization and construction of fused heterocycles from activated heteroarenes is still a subject to explore. In this work, we present a refined approach for both dearomatization of N-heteroarenes and the synthesis of fused heterocycles from activated heteroarenes ruthenium catalysis using paraformaldehyde along with additive and base. Notably, quinolinium salts with a hydrogen at the C-4 position yield a methoxymethyl-substituted fused cyclic product through the Thorpe Ingold effect. An innovative aspect of this research is the dual functionality of paraformaldehyde as both a hydride donor and electrophile, utilizing readily available feedstock chemicals. A broad range of electron withdrawing and donating substituents was tolerable under standardized reaction conditions.