Cationic Nickel Complexes with Weakly Coordinating Counterions and Their Application in the Asymmetric Cycloisomerisation of 1,6-Dienes

✍ Scribed by Christian Böing; Giancarlo Franciò; Walter Leitner

• Publisher: John Wiley and Sons
• Year: 2005
• Tongue: English
• Weight: 91 KB
• Volume: 347
• Category: Article
• ISSN: 1615-4150
• DOI: 10.1002/adsc.200505176

✦ Synopsis

Abstract

The influence of the counterion on cationic nickel catalysts for asymmetric cycloisomerisation of diethyl diallylmalonate (1a) and N,N‐diallyltosylamide (1b) is investigated. The activity of the catalysts formed from [Ni(η^3^‐allyl)(η^4^‐cod)]^+^ salts of weakly coordinating anions in combination with Wilke's azaphospholene ligand decreases in the order [Al{OC(CF~3~)~3~}~4~]^−^>[B{3,5‐(CF~3~)~2~‐C~6~H~3~}~4~]^−^>[Al{OC(CF~3~)~2~Ph}~4~]^−^ for 1a and [B{3,5‐(CF~3~)~2~‐C~6~H~3~}~4~]^−^> [Al{OC(CF~3~)~2~Ph}~4~]^−^>[Al{OC(CF~3~)~3~}~4~]^−^ for 1b, respectively. No significant influence on the enantioselectivity is observed for 1a whereas a marked increase in ee parallel to a decreasing activity is found for the cyclisation of 1b.