Preparation of naphthalenes via Pd‐catalyzed annulation of 5‐(2‐bromophenyl)pent‐3‐en‐1‐ynes under Suzuki‐Miyaura coupling conditions

• Published in: Journal of the Chinese Chemical Society (Taipei) Vol. 71; no. 10; pp. 1300 - 1308
• Main Authors: Hsu, Cheng‐Kai, Liu, Yi‐Hung, Liu, Shiuh‐Tzung
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley‐VCH Verlag GmbH & Co. KGaA 01-10-2024; Wiley Subscription Services, Inc
• Subjects: Chemical reactions; coupling; Crystal structure; cyclization; enyne; Naphthalene; Palladium
• ISSN: 0009-4536; 2192-6549
• DOI: 10.1002/jccs.202400215

Highly substituted naphthalene derivatives were prepared via palladium‐catalyzed reaction of 5‐(2‐bromophenyl)pent‐3‐en‐1‐ynes with arylboronic acids. Typically, reaction of 3‐bromo‐4‐(3‐(4‐chlorophenyl)‐5‐phenyl‐1‐(p‐tolyl)pent‐2‐en‐4‐yn‐1‐yl)‐N‐methylaniline (1a) with PhB(OH)2 in the presence of Pd(PPh3)4 as the catalyst under basic conditions provided 8‐benzhydryl‐7‐(4‐chlorophenyl)‐N‐methyl‐5‐(p‐tolyl)naphthalen‐2‐amine (2a) quantitatively. Overall, 19 new naphthalene compounds were obtained by this methodology and their structures were characterized by spectroscopic methods. In addition, crystal structure of 2j was determined to confirm the structural details. Reaction pathway leading to the desired product is also discussed.
Using palladium‐catalyzed reaction of 5‐(2‐bromophenyl)pent‐3‐en‐1‐ynes with arylboronic acids was studied. Reaction proceeds with C‐Br bond activation, migratory insertion, metathesis with arylboronate, and reductive elimination to yield the desired naphthalene derivatives.