Issue 17, 2010

Syntheses, X-ray crystal structures and reactivity of fluorenylidene- and dibenzosuberenylidene-allenes: convenient precursors to dispirotetracenes, di-indenotetracenes and 2-phenyl-11bH-dibenz[cd,h]azulene

Abstract

3,3-(Biphenyl-2,2′-diyl)-1-α,α,α-trifluoro-p-tolyl-allene, 9, sequentially forms head-to-tail, 12, cis-tail-to-tail, 13, and trans tail-to-tail, 14, 1,2-dialkylidene-cyclobutane dimers, each of which has been characterised by X-ray crystallography. Thermolysis at 180 °C yields the dispirotetracene, 15, and di-indenotetracene, 16; the latter compound forms an air-stable Diels–Alder adduct, 17, with N-methylmaleimide. In contrast, the dibenzo[a,d]cycloheptenylidene-allenes, (C14H10)C[double bond, length as m-dash]C[double bond, length as m-dash]C(Br)Ph, 20a, and (C14H10)C[double bond, length as m-dash]C[double bond, length as m-dash]C(H)Ph, 21a, do not dimerise under relatively mild conditions. However, protonation of the bromo-allene, 20a, and subsequent addition of hydride, provide a facile entry to the difficultly accessible bowl-shaped dibenz[cd,h]azulene framework, as in 30, that had not previously been structurally characterised. Among others, the X-ray crystal structures of 12, 13, 14, 17, 20a, 21a and 30 are reported.

Graphical abstract: Syntheses, X-ray crystal structures and reactivity of fluorenylidene- and dibenzosuberenylidene-allenes: convenient precursors to dispirotetracenes, di-indenotetracenes and 2-phenyl-11bH-dibenz[cd,h]azulene

Supplementary files

Article information

Article type
Paper
Submitted
06 Apr 2010
Accepted
08 Jun 2010
First published
27 Jul 2010

Org. Biomol. Chem., 2010,8, 3997-4010

Syntheses, X-ray crystal structures and reactivity of fluorenylidene- and dibenzosuberenylidene-allenes: convenient precursors to dispirotetracenes, di-indenotetracenes and 2-phenyl-11bH-dibenz[cd,h]azulene

E. V. Banide, C. O'Connor, N. Fortune, Y. Ortin, S. Milosevic, H. Müller-Bunz and M. J. McGlinchey, Org. Biomol. Chem., 2010, 8, 3997 DOI: 10.1039/C004868B

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