Palladium-Catalyzed Trimerizations of Terminal Arylalkynes: Synthesis of 1,3-Diaryl-2-arylethynyl-1,3-butadienes[1]

✍ Scribed by Yao-Ting Wu; Wei-Chih Lin; Chia-Ju Liu; Chuan-Yi Wu

• Publisher: John Wiley and Sons
• Year: 2008
• Tongue: English
• Weight: 315 KB
• Volume: 350
• Category: Article
• ISSN: 1615-4150
• DOI: 10.1002/adsc.200800182

✦ Synopsis

Abstract

Various 1,3‐diaryl‐2‐arylethynyl‐1,3‐butadienes 7 have been prepared by the Pd‐catalyzed trimerization of arylalkynes 4. Their structures and stereochemistry have been confirmed by X‐ray crystal analyses. This procedure provides high regioselectivity to generate adducts Z‐7 in moderate to excellent yields. The scope, limitations and regioselectivity of this reaction have been investigated. In DMSO at 180 °C, 1,3‐di(1‐naphthalenyl)‐2‐(1‐naphthalenylethynyl)‐1,3‐butadiene (7m) underwent 6π‐electrocyclization to form 2‐(1‐naphthalenyl)‐3‐(1‐naphthalenylethynyl)‐1,2‐dihydrophenanthrene (21). Under acidic conditions, (1__Z__)**‐**1,3‐diphenyl‐2‐(1‐phenylethynyl)‐1,3‐butadiene (Z‐7a) was converted to 1‐methyl‐3‐phenyl‐2‐(2‐phenyl‐1‐ethionyl)‐2‐indene (22) in 75% yield.