Parham cyclizations

The Parham cyclization of the iodinated imide 270 by BuLi in dry THF at —78°C afforded 1 lZ -hydroxy-l,3,4,6,7,l lZ -hexahydro[l,4]oxazine[3,4-a]iso-quinolin-4-one 258 (97JOC2080). Iodide-lithium exchange was faster then addition to the carbonyl group of imide 270 and intramolecular cyclization of the initially formed anion gave compound 258. 

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-... 

The well-known Parham cyclization of bromoaromatic carboxylic acid derivatives can be exemplified by the examples in equations (27)-(29). The reaction is usually run at very low temperature in ether or llIF and provides surprisingly good yields of aromatic ketones. The method has been reviewed recently. ... 

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. ... 

Other references related to the Parham cyclization are cited in the literature. ... 

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

Paal-Knorr Pyrrole Synthesis Parham Cyclization Passerini Reaction Patemo-Biichi Reaction Pauson-Khand Reaction Payne Rearrangement Pechmann Condensation Pechmann Pyrazole Synthesis Pellizzari Reaction Pelouze Synthesis Periodic Acid Oxidation Perkin Alicyclic Synthesis Perkin Reaction Perkin Rearrangement Perkow Reaction Peterson Reaction... 

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