Naphtho[b,e]dicyclobutene

Structure of 3,4-bis(trimethylsilyl)bicyclo[4.2.0]octa-1,3,5-triene

“…1. Positional parameters as well as bond lengths and angles are listed in Tables 1 and 2 The molecular geometry of this compound is consistent with those of other bicyclo [4.2.0] octa-1,3,5trienes (Mak & Trotter, 1964;MacDonald, Lawrence & Cava, 1965;Hardgrove, Templeton & Templeton, 1968;Lawrence & MacDonald, 1969;Allen & Trotter, 1970a,b;Crawford & Marsh, 1973;Thummel, Korp, Bernal, Harlow & Soulen, 1977;Webber, Petcher & Loosli, 1977;Winter & Straub, 1978;Hart, Jeffares, Teuerstein & Ward, 1978;Thummel & Nutakul, 1978;Straub, D6ring & Winter, 1979;Korp & Bernal 1979;Ward, 1980;Hart, Teuerstein, Jeffares, Kung & Ward, 1980). The average Si-C(methyl) bond lengths are in agreement with recently published values (Hursthouse & Malik, 1979).…”

Cyclobutarenes. Part 4. Biphenyleno[2,1-a]biphenylene

“…0.5 ppm, at 6 7.28. 23 The benzenoid protons are shifted to lowfield with respect to biphenylene and this, coupled with the comparatively small difference in shift between the a-and P-positions, appears to be characteristic of systems which can minimise 4n n-electron effects by localisation of an adjacent ring.6 This lowfield shift may also be indicative of a higher diatropic current in the terminal rings than that in biphenylene, owing to their higher degree of delocalisation (invariant PBOs 0.38 and 0.62, cf. biphenylene, 0.33 and 0.67).…”

Naphthocyclobutenes and Benzodicyclobutadienes: Synthesis in the Solid State and Anomalies in the Bond Lengths

“…[13] Recently, a new synthetic route to these 1,2-dihydrocyclobutaarenes through the thermal cyclization reaction of 1,2-diallenylarenes derived from a 1,2-diynediol by a propargyl rearrangement has been developed. [14] Reaction of 1,2-dibromobenzene (9) with 1,1-diphenyl-2-proyn-1-ol (10) in the presence of a Pdcatalyst [15] gives the 1,2-diynediol derivative 11.…”