Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Lithium-halogen exchange intramolecular cyclization

This reaction was initially developed by Parham in 1975 and extended primarily by Bradsher after Parham s death in 1976. It is the synthesis of aryl or heteroaryl ring fused carbocylces or heterocycles through the intramolecular reaction between a side chain electrophile and an aryl or heteroaryllithium generated from lithium-halogen exchange. Therefore, this reaction is generally known as the Parham cyclization. Occasionally, it is also referred to as the Parham reaction. J This reaction is very useful for the synthesis of alkaloids. ... [Pg.2114]

The very fast metal-halogen exchange allows intramolecular cyclization reactions, which are known as Parham cyclizations171. The potential of Parham cyclizations as a useful stereoselective cyclization procedure has proven to be extremely interesting172. Thus, it has been recently demonstrated that iodinated IV-phenethylimides tolerate iodine-lithium exchange, giving rise to the isoquinoline nucleus 304, via a Parham-... [Pg.117]

The Parham cyclization is the generation by halogen-lithium exchange of aryllith-iums and heteroaryllithiums, and their subsequent intramolecular cyclization onto an electrophilic site. [Pg.413]


See other pages where Lithium-halogen exchange intramolecular cyclization is mentioned: [Pg.247]    [Pg.160]    [Pg.353]    [Pg.52]    [Pg.299]    [Pg.329]    [Pg.62]   
See also in sourсe #XX -- [ Pg.214 ]




SEARCH



Cyclizations intramolecular

Halogen exchange

Intramolecular cyclization

Intramolecular exchange

Lithium-halogen exchange

© 2024 chempedia.info