Palladium(0)-Catalyzed Tandem Cyclization of Allenenes

✍ Scribed by Hiroaki Ohno; Kumiko Miyamura; Yusuke Takeoka; Tetsuaki Tanaka

• Publisher: John Wiley and Sons
• Year: 2003
• Tongue: English
• Weight: 125 KB
• Volume: 115
• Category: Article
• ISSN: 0044-8249
• DOI: 10.1002/ange.200351011

✦ Synopsis

Allenes have become more versatile intermediates in organic synthesis as a result of recent developments in transitionmetal-catalyzed reactions. In particular, allenes of general type 2, which bear a nucleophilic moiety such as a nitrogen-or oxygen-containing functional group, are a well-known class of compounds that undergo a variety of palladium(0)-catalyzed cyclizations to form cyclic products 4 or 5 (Scheme 1). Recent studies in this area revealed that three- [4] or fourmembered heterocycles [5] could also be synthesized efficiently by the palladium-catalyzed cyclization of allenes 2. In sharp contrast, however, palladium-catalyzed reactions of allenes that contain an additional multiple bond have scarcely been studied.

In analogy to the reactions of allenes 2, which terminate with the intramolecular reaction of the p-allyl palladium intermediate with a nucleophile, the allenene 6 could undergo a tandem cyclization of the type shown in Scheme 1 under Scheme 1. Palladium-catalyzed cyclization of allenes.