Regioisomeric and substituent effects upon the outcome of the reaction of 1-borodienes with nitrosoarene compounds

Eberlin, Ludovic; Carboni, Bertrand; Whiting, Andrew

Abstract

A study of the reactivity of 1-borodienes with nitrosoarene compounds has been carried out showing an outcome that differs according to the hybridization state of the boron moiety. Using an sp2 boron substituent, a one-pot hetero-Diels–Alder/ring contraction cascade occurred to afford N-arylpyrroles with low to good yields depending on the electronic properties of the substituents on the borodiene, whereas an sp3 boron substituent led to the formation of stable boro-oxazines with high regioselectivity in most of the cases, in moderate to good yields. 1H and 11B NMR studies on two boro-oxazine regioisomers showed that selective deprotection can be performed. Formation of either the pyrrole or the furan derivative is pH- and regioisomer-structure-dependent. The results obtained, together with previous B3LYP calculations, support mechanistic proposals which suggest that pyrrole, or furan, formation proceeds via oxazine formation, followed by a boryl rearrangement and an intramolecular addition–elimination sequence.

Citation

Eberlin, L., Carboni, B., & Whiting, A. (2015). Regioisomeric and substituent effects upon the outcome of the reaction of 1-borodienes with nitrosoarene compounds. Journal of Organic Chemistry, 80(13), 6574-6583. https://doi.org/10.1021/acs.joc.5b00593

• Journal Article Type: Article
• Acceptance Date: Jun 3, 2015
• Online Publication Date: Jun 3, 2015
• Publication Date: Jul 2, 2015
• Deposit Date: Jun 12, 2015
• Publicly Available Date: Jun 3, 2016
• Journal: Journal of Organic Chemistry
• Print ISSN: 0022-3263
• Electronic ISSN: 1520-6904
• Publisher: American Chemical Society
• Peer Reviewed: Peer Reviewed
• Volume: 80
• Issue: 13
• Pages: 6574-6583
• DOI: https://doi.org/10.1021/acs.joc.5b00593
• Public URL: https://durham-repository.worktribe.com/output/1403931