SRN1 reaction propagation

Substituted 2,3-dihydro-l-H-indoles 26 are accessible by the versatile application of a 5-exo ring closure process during the propagation cycle in the SRN1 reaction [67]. Following the initial ET and fragmentation of the radical anion of the substrate, the... 

Argiiello, J.E., Penenory, A.B. and Rossi, R.A. (2000) Quantum yields of the initiation step and chain propagation turnovers in SRN1 reactions photostimulated reaction of l-iodo-2-methyl-2-phenyl propane with carbanions in DMSO. Journal of Organic Chemistry, 65, 7175-7182. 

The novelty of this work involves the versatile application of 5-exo ring closure processes during the propagation cycle of the SRN1 reaction the alkyl radical intermediates formed then reacted with the nucleophiles to afford the ring closure-substituted heterocycles. The factors governing the observed product distribution are discussed and one of the examples is illustrated below <02JOC8500>. 

For nucleophiles which are unable to initiate the reaction but are quite reactive in the propagation steps, the addition of minute amounts of another nucleophile capable of initiating the reaction increases the generation of intermediates. This allows the less-reactive initiation-nucleophile to start its own propagation. This entrainment reaction allows an extension of the SRN1 mechanism to nucleophiles that are poor donors, supporting the chain nature of the reaction [9]. 

The photostimulated reaction of 1,8-diiodonaphthalene with p-methyl-benzenethio-late ions in DMSO yields the substituted cyclized product 10-methyl-7-thia-benzo[de] anthracene (31) in moderate yield (Scheme 10.58) [54], The mechanism proposed to explain product 31 involves an intramolecular radical cyclization after monosubstitution in the propagation cycle of the SRN1 process. 

Halothiophenes undergo photostimulated reaction with acetone enolate ion to form substitution products (76H(5j377). This is believed to occur by the radical-chain SRN1 mechanism. The propagation steps are as follows ... 

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