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

Saleh, Basil A., Smith, Keith, Elliott, Mark Christopher ORCID: https://orcid.org/0000-0003-0132-0818, Jones, Dyfyr Heulyn, Kariuki, Benson M. ORCID: https://orcid.org/0000-0002-8658-3897 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:	08 Nov 2023 13:30
URI:	https://orca.cardiff.ac.uk/id/eprint/94970

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