Reactions of an aluminum(I) reagent with 1,2-, 1,3-, and 1,5-dienes: dearomatization, reversibility, and a pericyclic mechanism

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Title: Reactions of an aluminum(I) reagent with 1,2-, 1,3-, and 1,5-dienes: dearomatization, reversibility, and a pericyclic mechanism
Authors: Bakewell, C
Garçon, M
Kong, RY
O’Hare, L
White, AJP
Crimmin, MR
Item Type: Journal Article
Abstract: Addition of the aluminum(I) reagent [{(ArNCMe)2CH}Al] (Ar = 2,6-di-iso-propylphenyl) to a series of cyclic and acyclic 1,2-, 1,3-, and 1,5-dienes is reported. In the case of 1,3-dienes, the reaction occurs by a pericyclic reaction mechanism, specifically a cheletropic cycloaddition, to form aluminocyclopentene-containing products. This mechanism has been examined by stereochemical experiments and DFT calculations. The stereochemical experiments show that the (4 + 1) cycloaddition follows a suprafacial topology, while calculations support a concerted albeit asynchronous pathway in which the transition state demonstrates aromatic character. Remarkably, the substrate scope of the (4 + 1) cycloaddition includes styene, 1,1-diphenylethylene, and anthracene. In these cases, the diene motif is either in part, or entirely, contained within an aromatic ring and reactions occur with dearomatisation of the substrate and can be reversible. In the case of 1,2-cyclononadiene or 1,5-cyclooctadiene, complementary reactivity is observed; the orthogonal nature of the C═C π-bonds (1,2-diene) and the homoconjugated system (1,5-diene) both disfavor a (4 + 1) cycloaddition. Rather, reaction pathways are determined by an initial (2 + 1) cycloaddition to form an aluminocyclopropane intermediate which can in turn undergo insertion of a further C═C π-bond, leading to complex organometallic products that incorporate fused hydrocarbon rings.
Issue Date: 6-Apr-2020
Date of Acceptance: 1-Mar-2020
DOI: 10.1021/acs.inorgchem.9b03701
ISSN: 0020-1669
Publisher: American Chemical Society (ACS)
Journal / Book Title: Inorganic Chemistry
Volume: 59
Issue: 7
Copyright Statement: © 2020 American Chemical Society. This document is the Accepted Manuscript version of a Published Work that appeared in final form in Inorganic Chemistry, after peer review and technical editing by the publisher. To access the final edited and published work see
Sponsor/Funder: Commission of the European Communities
Funder's Grant Number: 677367
Keywords: Science & Technology
Physical Sciences
Chemistry, Inorganic & Nuclear
0302 Inorganic Chemistry
0306 Physical Chemistry (incl. Structural)
0399 Other Chemical Sciences
Inorganic & Nuclear Chemistry
Publication Status: Published
Article Number: acs.inorgchem.9b03701
Online Publication Date: 2020-03-24
Appears in Collections:Chemistry
Faculty of Natural Sciences
Grantham Institute for Climate Change