Alkyl radicals have been cyclised onto pyrroles, imidazoles and pyrazoles, and acyl radicals cyclised onto pyrroles, using Bu3SnH-, (TMS)3SiH- and Bu3GeH-mediated aromatic homolytic substitution for the synthesis of bicyclic N-heterocycles. The reactions yield intermediate π-radicals that lose hydrogen in the?rearomatisation step of the aromatic homolytic substitution. Mechanistic studies of these rearomatisation steps indicate aromatic homolytic substitution in which the initiator or breakdown products from the inhibitor are responsible for the H-abstraction step.
Allin, Steven M.,Barton, William R.S.,Russell Bowman,Bridge (née Mann), Emma,Elsegood, Mark R.J.,McInally, Tom,McKee, Vickie
p. 7745 - 7758
(2008/12/21)
Bu3SnH mediated oxidative radical cyclisation onto imidazoles and pyrroles
A new protocol using radical cyclisation has been developed for the synthesis of [1,2-c]-fused imidazoles and [1,2-a]-fused pyrroles. The intermediate nucleophilic N-alkyl radicals, generated using Bu3SnH from N- (ω-bromoalkyl) or N-[ω-(phenylselanyl)alkyl] imidazoles and pyrroles, undergo regio-selective radical cyclisalion onto the azole rings followed by oxidative re-aromatisation.
Aldabbagh, Fawaz,Russell Bowman,Mann, Emma,Slawin, Alexandra M.Z.
p. 8111 - 8128
(2007/10/03)
Oxidative radical cyclisations onto imidazoles and pyrroles using Bu3SnH
Oxidative radical cyclisation using Bu3SnH has been used for the synthesis of [1,2-c]-fused imidazoles and [1,2-a]-fused pyrroles from imidazolecarbaldehydes and acylpyrroles respectively. The intermediate nucleophilic N-alkyl radicals cyclise onto imidazole and pyrrole rings followed by oxidative re-aromatisation.
Aldabbagh, Fawaz,Bowman, W. Russell,Mann, Emma
p. 7937 - 7940
(2007/10/03)
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