Isotoluene intermediate

Photolysis of 1 -benzyl- 1-methylsilacyclobutane, which proceeds via rearrangement to an isotoluene intermediate followed by ring opening, produces l-propyl-l-methyl-2,3-benzosilacyclobutene in quantitative yield <2000CJC1459>. 

Although 1,2,4,6-heptatetraene (22) and its derivatives have largely been studied because of the mechanism of their thermocyclization to alkyl aromatics - in the simplest case, 22 isomerizes to toluene (333) via isotoluene (332) as an intermediate (Scheme 5.50) [8, 79, 80, 83] - other reactions of this interesting combination of conjugated and cumulated p-systems are also known. 

Conjugated systems, including 1,3-butadienes, diene-allenes, enyne-allenes, enediynes, dienediynes, and enediallenes, were synthesized via organoboranes. A wide array of cascade cyclization reactions involving high energy intermediates, such as o-isotoluenes, biradicals, o-quinodimethanes, benzocyclobutadienes, and enyne-ketenes, were initiated from these unsaturated compounds. 

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