457925-22-3Relevant academic research and scientific papers
Bu3SnH-mediated radical cyclisation onto azoles
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)
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.
Radical cyclisation onto pyrazoles: Synthesis of withasomnine
Allin, Steven M.,Barton, William R.S.,Bowman, W.Russell,McInally, Tom
, p. 4191 - 4193 (2007/10/03)
A novel synthetic protocol for the synthesis of [1,2-b]-fused bicyclic pyrazoles has been developed using radical cyclisation. The protocol uses cyclisation of pyrazole-1-(ω-alkyl) radicals generated from 1-[ω-(phenylselenyl)alkyl]-pyrazole precursors. The pyrazole natural product, withasomnine (3-phenyl-5,6-dihydro-4H-pyrrolo[1,2-b]pyrazole), and larger ring analogues have been synthesised in good yield using the protocol. A Bu3SnH-mediated oxidative cyclisation mechanism is facilitated by azo or Et3B radical initiators acting as oxidants of the intermediate π-radicals.
