Concise synthesis of α-substituted 2-benzofuranmethamines and other 2-subsituted benzofurans via α-substituted 2-benzofuranmethyl carbocation intermediates

• Main Authors: Nikhom Wongsa, Ubonta Sommart, Thunwadee Ritthiwigrom, Arife Yazici, Somdej Kanokmedhakul, Kwanjai Kanokmedhakul, Anthony C. Willis, Stephen G. Pyne
• Format: Journal
• Published: 2018
• Subjects: Chemistry
• Online Access: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84873325933&origin=inward; http://cmuir.cmu.ac.th/jspui/handle/6653943832/52406
• Institution: Chiang Mai University

Propargyl amines 4, where R3 is aryl, undergo 5-exo-dig cyclization reactions under relatively mild conditions (AgNO3, DMF, 60 C, 1 h) to give 3-amino-2,3-dihydro-2-arylmethylidenebenzofurans 5 (R 3 = aryl). In contrast, substrates where R3 is alkyl undergo competing 6-endo-dig and 5-exo-dig cycliza...