A route to 3H-1,2-diazepines by the 1,7-electrocyclisation of α,βγ,δ-unsaturated diazo-compounds

Robertson, Ian R.; Sharp, John T.

doi:10.1039/c39830001003

Cited by 8 publications

(6 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…(38; R,R' = H and Me) derived from (E)-and (Z)-o-acetyl-Pmethylstyrenes [equation (6)]. The (E)-isomer again gave the benzodiazepine (39) (89%) while the (Z)-isomer gave only carbene products, in this case a mixture of hydrocarbons containing predominantly ( > 90%) 2,3-dimethylindene (37) as shown by comparison of its 'H n.m.r.…”

Section: Resultsmentioning

confidence: 99%

“…and more recently to monocyclic 3H-1,2diazepines. The objective of this work was to examine the reactions of the diazo compounds (4) of the same type without such a hydrogen atom but having instead a group X which it was hoped would undergo either [ 1,5]-migration (suprafacial on X) to give the 1H-benzodiazepine (6) or [1,7]-migration (antarafacial on X) to give the 3H-(7) or SH-analogue (8) (Scheme 1). A mechanistic study on a related reaction which involves cyclisation at an aromatic rather than an olefinic carbon atom has shown that the cyclisation step is an equilibrium and that the second step is a wholly intramolecular migration.…”

mentioning

confidence: 99%

“…and more recently to monocyclic 3H-1,2diazepines. 6 The formation of compounds (3) from (1) is thought to take place via two steps, an 8n-electron 1,7electrocyclisation to give the intermediate (2) followed by a [ 1,5]-sigmatropic hydrogen shift. A mechanistic study on a related reaction which involves cyclisation at an aromatic rather than an olefinic carbon atom has shown that the cyclisation step is an equilibrium and that the second step is a wholly intramolecular migration.…”

mentioning

confidence: 99%

See 2 more Smart Citations

1,7-Electrocyclisation and carbene reactions of o-alkenylaryldiazoalkanes: the effect of alkene configuration on the mode of reaction

Munro¹,

Sharp²

1984

J. Chem. Soc., Perkin Trans. 1

Self Cite

View full text Add to dashboard Cite

The 1,7-8.rc-electron electrocyclisation of o-alkenylaryldiazoalkanes (1 ) to give 1 H-2,3-benzodiazepines (3) takes place readily for substrates with a cis-hydrogen atom at the cyclisation site, but is blocked b y phenyl or methyl groups at that position. Such compounds react only via loss of nitrogen, the former, e.g. (18), to give naphtho[a]cycloheptenes (20) b y a n e w intramolecular carbene reaction, and the latter to give carbene 'dimers', azines, products of solvent insertion, and in one case an indene (37). The blocking effect of cis-methyl and -phenyl groups is attributed to steric hindrance in a helical transition state (42) for the 1,7-electrocyclisation. The results are also discussed in relation t o the two possible primary processes of 1,7-electrocyclisation and 1 ,I -cycloaddition in the reactions of the isoelectronic systems (43) and (47) containing nitrilium and diazonium betaines. R H R' H R' (3) X (13; R = Me) gave the carbene 'dimer' (15; R = Me) (40%) and the azine (16; R = Me) (38%), formed by reaction of the Me H \ + -C=N=N * The conformational assignments of the proximate products (29) and (31) [and also (33) and (%)I are based on a transition state for ring closure of the type shown in (42).

show abstract

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

1,7-Electrocyclisation and carbene reactions of o-alkenylaryldiazoalkanes: the effect of alkene configuration on the mode of reaction

Munro¹,

Sharp²

1984

J. Chem. Soc., Perkin Trans. 1

Self Cite

View full text Add to dashboard Cite

show abstract

“…Thus, the a,b,g,d-unsaturated diazoalkane 10 should emerge from 9. The 1,7-electrocyclization of such diazoalkanes to 3H-diazepines has precedent [12], which is why we propose the conversion of 10 into 11. This diazepine is considered to be the point of bifurcation of the pathway, since the 1,5-migration of the iminoacetyl group leads to the 4H-1,2-diazepines 4 and 5, whereas an allyl rearrangement with ring contraction gives rise to 6 and 7.…”

mentioning

confidence: 99%

The Thermolysis of the Cycloadducts between Aryl Azides and Hexamethyl‐Dewar‐Benzene Revisited

Christl

Lesch

Deuerlein

2005

Helvetica Chimica Acta

View full text Add to dashboard Cite

Dedicated to Professor Rolf Huisgen on the occasion of his 85th birthdayThe reactions of 1-azido-2,4,6-trimethyl-and 1-azido-2,6-dimethylbenzene with hexamethyl-Dewarbenzene (HMDB) give rise to the pentamethyl(iminoethyl)-4H-1,2-diazepines 4 and 5, respectively. The Xray crystal-structure analysis of 5 unequivocally established these unexpected structures, which motivated us to re-investigate the thermolysis of the adduct 1a of HMDB and azidobenzene. Previously, the triazonine 2 was reported to be the major product, but this interpretation could not be corroborated now, and, instead, the 1-aminopyrrole 6 was identified as the true compound. The structure of the analogous compound 7, obtained by thermolysis of the (1-azido-4-nitrobenzene)-HMDB adduct 1b, was confirmed by X-ray diffraction. In the original literature investigation, a second product had been isolated, in addition to the alleged 2, by chromatographic purificiation of the thermolysis mixture, and structure 3 had been ascribed to it. It turns out now that this compound is not a valence isomer of the major product, but a hydrolysis product, i.e., the ketone 8. The formation of the rather different compounds 4 and 5 on the one hand, and 6 and 7 on the other hand, can be rationalized straightforwardly by a sequence of pericyclic reactions leading to 3H-1,2-diazepines 11 as common intermediates, which are converted to either 4 and 5, or 6 and 7, depending on the nature of the aromatic group.

show abstract

“…In cases where it is olefinic in nature, e.g. in (2), the diazo compounds cyclise only via 1,7 closure to give 3H-1,2-diazepines, e.g. (3),2 and produce n o isolable quantities of the 3-vinylpyrazoles (1) t which would have resulted from the alternative 1,5 closure.…”

mentioning

confidence: 99%

Electrocyclic aromatic substitution by the diazo group. Part 4. Periselectivity studies on the cyclisation of 1-thienyl-3-diazoalkenes: a route to 3H-thieno[1,2]diazepines

Miller¹,

Sharp²

1984

J. Chem. Soc., Perkin Trans. 1

Self Cite

View full text Add to dashboard Cite

A route to 3H-1,2-diazepines by the 1,7-electrocyclisation of α,βγ,δ-unsaturated diazo-compounds

Cited by 8 publications

References 0 publications

1,7-Electrocyclisation and carbene reactions of o-alkenylaryldiazoalkanes: the effect of alkene configuration on the mode of reaction

1,7-Electrocyclisation and carbene reactions of o-alkenylaryldiazoalkanes: the effect of alkene configuration on the mode of reaction

The Thermolysis of the Cycloadducts between Aryl Azides and Hexamethyl‐Dewar‐Benzene Revisited

Electrocyclic aromatic substitution by the diazo group. Part 4. Periselectivity studies on the cyclisation of 1-thienyl-3-diazoalkenes: a route to 3H-thieno[1,2]diazepines

Contact Info

Product

Resources

About