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Reactions of organoboranes with carbanions bearing three potential leaving groups: unusual processes, products and mechanisms

Saleh, Basil A., Smith, Keith, Elliott, Mark Christopher, Jones, Dyfyr Heulyn, Kariuki, Benson M. and El Hiti, Gamal A. 2016. Reactions of organoboranes with carbanions bearing three potential leaving groups: unusual processes, products and mechanisms. Tetrahedron 72 (44) , pp. 6914-6928. 10.1016/j.tet.2016.09.005

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Abstract

Known reagents that transfer three alkyl groups of a trialkylborane intramolecularly to a single carbon atom lack features to influence stereochemistry. We have investigated four reagents of type LiCCl2X, where X might be amenable to variation. All behaved differently. With X=OR (R=cyclohexyl, menthyl), the reagent decomposed, leading to only low yields of triple migration products. With X=S(O)Ph, a single migration occurred, followed by isomerisation to boron enolate-like species that hydrolysed to α-chloroalkyl phenyl sulfoxides or reacted with aldehydes to aldol-like products. With X=SO2Ph, the major product was the corresponding α,α-dichloroalkyl phenyl sulfone, apparently formed through a redox reaction. With X=S(O)(NMe)Ph, products of three intramolecular alkyl migrations were obtained with unhindered trialkylboranes. Attempts have been made to gain understanding of the sulfoxide process by investigating proportions of aldol-like products, using X-ray crystallography and ab initio calculations.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Chemistry
Subjects: Q Science > QD Chemistry
Uncontrolled Keywords: Trialkylborane; Sulfoximine; Rearrangement; Sulfoxide; Sulfone
Publisher: Elsevier
ISSN: 0040-4020
Funders: EPSRC
Date of First Compliant Deposit: 11 October 2016
Date of Acceptance: 5 September 2016
Last Modified: 12 Oct 2017 22:32
URI: http://orca-mwe.cf.ac.uk/id/eprint/94970

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