Cycloheptatriene, CHT

The electrochemical reduction of cycloheptatriene (CHT) in liquid ammonia takes place at about —2.5 V vs SCE and forms the radical anion of CHT. The radical anion is stable in ammonia on the voltammetric time scale but decays slowly by disproportionation and coupling reaction pathways to give respectively 1,3- and 1,4-cycloheptadienes (total yield 34-39%) and C14H18 (in yields of 55-58%) isomers which incorporate the bitropyl carbon skeleta20. 

Riot-control agents—such as CS, CN, and CR—are solids. Edge-wood scientists felt that dissemination and decontamination would be simpler with a volatile liquid agent. Research led to the produc tlon and testing of l-methoxy-l,3,5-cycloheptatriene (CHT, EA 4923), a liquid substance of high volatility (Table 4-40) with physiologic effects typical of riot-control agents (e.g., lacrlmation, skin irrl tatlon, and mucous membrane irritation). 

As an example, the suprafacial [1,7] sigmatropic H-shift will be considered that occurs on irradiation of 1,3,5-CHT with formation of bicyclo[3.2.0]hepta-2,6-diene (BHD) as a minor product. In 1-substituted CHT this [1,7]-H shift is regiose-lective in 1-cyano-cycloheptatriene (CN-CHT) the hydrogen atom moves exclusively to the unsubstituted terminal carbon of the heptatriene moiety, whereas in 1-methyl-cyclohep-tatriene (Me-CHT) only 2% of the product exhibits this regio-chemistry and 98% corresponds to a hydrogen shift toward the substituted carbon, as shown in Scheme 6.1. Different models have been proposed to explain this regioselectivity. ... 

Complexes containing CHT may be obtained by reactions of cycloheptatriene compounds with triphenylmethyl tetrafluoroborate ... 

The compound Crcp(CHT) is obtained by dehydrogenation of cycloheptatriene-cyclopentadienylchromium using a platinum catalyst,... 

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