title: Concise synthesis of 1,2-dihydroisoquinolines and 1H-isochromenes by carbophilic lewis acid-catalyzed tandem nucleophilic addition and cyclization of 2-(1-alkynyl)arylaldimines and 2-(1-alkynyl)arylaldehydes.
abstract: By using carbophilic Lewis acids, In(OTf)3, NiCl2, and AuCl(PPh3)/AgNTf2, a concise and efficient synthesis of 1,3-disubstituted 1,2-dihydroisoquinolines has been achieved via tandem nucleophilic addition and cyclization of 2-(1-alkynyl)arylaldimines. Addition of proton sources such as water, CF3CH2OH, and 2,6-di-tert-butyl-4-methoxyphenol was essential for the Lewis acid-catalyzed tandem reactions with organometallic reagents. By switching these catalysts, various types of nucleophiles such as allylstannanes, silyl enol ethers, alkenylboronic acids, and active methylene compounds could be introduced at the C1 position of 1,2-dihydroisoquinolines in this transformation. Furthermore, this method proved to be applicable to the synthesis of 1H-isochromene derivatives via the same tandem reaction of 2-(1-alkynyl)arylaldehydes.
authors.affiliation: Graduate School of Pharmaceutical Sciences, Kyoto University, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan.
authors.forename: Shingo
authors.initials: S
authors.lastname: Obika
authors.forename: Hideki
authors.initials: H
authors.lastname: Kono
authors.forename: Yoshizumi
authors.initials: Y
authors.lastname: Yasui
authors.forename: Reiko
authors.initials: R
authors.lastname: Yanada
authors.forename: Yoshiji
authors.initials: Y
authors.lastname: Takemoto
mesh_terms: D000447:Aldehydes / Q000737:chemistry*; D000480:Alkynes / Q000138:chemical synthesis / Q000737:chemistry*; D001578:Benzopyrans / Q000138:chemical synthesis*; D002384:Catalysis; D003500:Cyclization; D007097:Imines / Q000737:chemistry*; D007546:Isoquinolines / Q000138:chemical synthesis*
chemical_list: D000447:Aldehydes; D000480:Alkynes; D001578:Benzopyrans; C109853:G 1617; D007097:Imines; D007546:Isoquinolines