| Abstract
| - 9,10-Bis[methoxy(trimethylsilyl)methyl]anthracenes (24), synthesized from 9,10-dilithioanthracene(26) and bromomethoxytrimethylsilylmethane (27, 2 equiv), decompose (550−650 °C/10-3 mmHg)carbenically to dibenzo[b,f]pentalene (28, >48%). 9,10-Anthryldicarbenes 39 or their equivalentsconvert to pentalene 28 rather than di-peri-cyclobutanthracenes 30 and 31, benzobiphenylene 32,or extended rearrangement products 33−38. Formation of 28 from 24 raises questions with respectto the behavior of 1,3,4,6-cycloheptatetraenyl-1-carbenes 49, 2,4,5,7-cyclooctatetraenylidene 51, 2,5,7-cyclooctatriene-1,4-diylidene 52, 1,2,4,5,7-cyclooctapentaene 53, and bicyclo[4.1.0]heptatrienyl-1-carbenes 54 and to carbon-skeleton and hydrogen rearrangements of anthryldicarbenes 39 and/ortheir equivalents at various temperatures. 1,5-Bis[methoxy(trimethylsilyl)methyl]anthracenes (25),prepared from 1,5-diiodoanthracene (63) and methoxytrimethylsilylmethylzinc bromide (57, 2 equiv)as catalyzed by PdCl2(PPh3)2, yield the di-peri-carbenic reaction product 1H,5H-dicyclobuta[de,kl]anthracene (30, >40%) on pyrolysis at 550−650 °C/10-3 mmHg. Proof of structure and variousaspects of the mechanisms of formation of 30 are discussed.
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