Scope of the homo-Diels-Alder reaction

Fickes, Garry N.; METZ, T. E.

doi:10.1021/jo00415a016

Cited by 32 publications

(13 citation statements)

References 12 publications

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“…This ring contraction reaction of 1,5-cyclooctadiene presents similarities to known homo Diels–Alder cycloadditions . While homo Diels–Alder [2 + 2 + 2] cycloadditions of homoconjugated dienes can occur under transition-metal catalysis or in the case of very reactive dienophiles without a catalyst, − cheletropic reactions with homoconjugated dienes are extremely rare.…”

Section: Resultsmentioning

confidence: 71%

Reactions of an Aluminum(I) Reagent with 1,2-, 1,3-, and 1,5-Dienes: Dearomatization, Reversibility, and a Pericyclic Mechanism

et al. 2020

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The reactions of an aluminium(I) reagent with a series of 1,2-, 1,3-and 1,5-dienes are 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 interrogated 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 dienes that are either in part, or entirely, contained within aromatic rings. In these cases, reactions occur with dearomatisation of the substrate and can be reversible. In the case of 1,2-or 1,5-dienes complementary reactivity is observed; the orthogonal nature of the C=C p-bonds (1,2-diene) and the homoconjugated system (1,5-diene) both disfavour 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 p-bond leading to complex organometallic products that incorporate fused hydrocarbon rings.

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Section: Resultsmentioning

confidence: 71%

Reactions of an Aluminum(I) Reagent with 1,2-, 1,3-, and 1,5-Dienes: Dearomatization, Reversibility, and a Pericyclic Mechanism

et al. 2020

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“…The data are similar to a related 1,4-bis(trimethylsilyl)but-2-ene-1,4-diyl complex prepared through a salt-metathesis route. 43 The structure of 2c as determined by single crystal X-ray diffraction is very similar and this molecule crystallises as a -- cycloadditions of homoconjugated dienes can occur under transition metal catalysis or in the case of very reactive dienophiles without a catalyst, [45][46][47] cheletropic reactions with homoconjugated dienes are extremely rare.…”

Section: 3-dienes and Dearomatisationmentioning

confidence: 93%

Reactions of an Aluminium(I) Reagent with 1,2-, 1,3- and 1,5-Dienes: Dearomatisation, Reversibility, and a Pericyclic Mechanism

Bakewell¹,

Garçon²,

Kong³

et al. 2019

Preprint

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The reactions of an aluminium(I) reagent with a series of 1,2-, 1,3- and 1,5-dienes are 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 interrogated 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 dienes that are either in part, or entirely, contained within aromatic rings. In these cases, reactions occur with dearomatisation of the substrate and can be reversible. In the case of 1,2- or 1,5-dienes complementary reactivity is observed; the orthogonal nature of the C=C π-bonds (1,2-diene) and the homoconjugated system (1,5-diene) both disfavour 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.

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“…The electrophilic bromination reaction of norbornadiene, which gave the skeleton-rearranged dibromide, is of interest in connection with the intramolecular mutual interaction of the two double bonds (Winstein & Shatavsky, 1956;Schmerling, Luvisi & Welch, 1956). On the other hand, in the case of the norbornadiene homologues, bicyclodienes (la) and (4), 1,5-and 1,2-addition, under similar conditions, of the bromine to the common cyclohexa-l,4-diene part in the molecule occurred to give dibromides without any skeletonrearrangement products (Fickes & Metzs, 1978;Gagneux & Grob, 1959;Grob & Hostynek, 1963). Regarding the synthetic work for the norbornadiene homologues bicyclo[4.2.2]deca-7,9-diene and bicyclo[5.2.2]undeca-8,10-diene (Satake, Usumoto, Hikasa, Kimura, Kishima & Morosawa, 1992), a reinvestigation of the bromination reaction of the bicyclodiene (la) and its dimethoxycarbonyl derivative (lb) was undertaken in order to investigate a systematic change in features of the mutual intramolecular interactions of the 1,4cyclohexadiene part of the structure.…”

Section: Commentmentioning

confidence: 99%