Vilsmeier−Haack−Arnold Acylation of the Reductively Activated Benzene Ligand in [Mn(CO)3(η4-C6H6)]

• Published in: Organometallics 2004-12, Vol.23 (25), p.5939-5943
• Main Authors: Shao, Li, Badger, Paul D, Geib, Steven J, Cooper, N. John
• Format: Article
• Language: English
• ISSN: 0276-7333; 1520-6041
• DOI: 10.1021/om040103g

The major product from the reaction of the enoliminium ester [Me2CHC(OSO2CF3)NMe2]+ (5 + ) with [Mn(η4-C6H6)(CO)3]- (2 - ) is [Mn(CO)3{η5-C6H6C(iPr)NMe2}]+ (6 + ; X-ray), in which an iminium ion has been added to the reductively activated benzene ligand in 2 - . Minor products include [{Mn(CO)3(η5-C6H6)-exo}2C(iPr)NHMe2]CF3SO3 (8(CF3SO3); X-ray) and [{Mn(CO)3(η5-C6H6)-exo}2C(iPr)NMe2] (7), with two Mn(CO)3 groups attached to the enoliminium ester derived backbone. The mechanistic relationship between the reactions that yield to formation of 6 + , 8 + , and 7 are unclear, since an increase in the ratio of 2 - to 6 + does not increase the yield of 7, and reaction of 2 - with the keteniminium salt prepared by reaction of 5 + with collidine leads directly to 6 + . Hydrolysis of 6(PF6) generates [Mn(CO)3{η5-C6H6C(iPr)O}] (9), in which the benzene ligand in 2 - has been acylated.