Scientific article

The Photochemical Synthesis and Denitrogenation of 8,9-diazadibenzo[c, e]isobullvalene

Published inHelvetica chimica acta, vol. 72, no. 8, p. 1722-1728
Publication date1989

Starting from dibenzo[a, c]cyclooctene (4) and 4-methyl-3H-1,2,4-triazol-3,5(4H)-dione (MTAD), the strained skeleton of the title azo compound 1 is assembled in a tandem photo-Diels-Alder addition/di-p-methane rearrangement sequence. The synthesis is completed by a stepwise hydrolytic oxidation of the ensuing triazolidine-dione 2 with nickel peroxide. Thermolysis of 1 in benzene solution is shown to be governed by an initial 1,3-dipolar cycloreversion which leads, via an intermediate diazo compound 11, to cyclobuta[1]phenanthrene 8 and two further carbene-derived C16H12 products. Photolysis of 1 at 350 nm leads in modest yield (12%), via a diazenyl diradical, to an unstable bridged bicyclobutane 10 (dibenzooctavalene). MNDO calculations suggest the latter to have a rapidly inverting, twisted structure of C2 symmetry.

Citation (ISO format)
BURGER, Ulrich et al. The Photochemical Synthesis and Denitrogenation of 8,9-diazadibenzo[c, e]isobullvalene. In: Helvetica chimica acta, 1989, vol. 72, n° 8, p. 1722–1728. doi: 10.1002/hlca.19890720809
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Article (Published version)
ISSN of the journal0018-019X

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