From 3,4-dinitrothiophene to 1,2-diaryl-4-nitrobenzenes through ( E , E , E )-1,6-diaryl-3-nitro-1,3,5-hexatrienes
作者:Carlo Dell'Erba、Antonella Gabellini、Angelo Mugnoli、Marino Novi、Giovanni Petrillo、Cinzia Tavani
DOI:10.1016/s0040-4020(01)00898-5
日期:2001.10
The reactions between 1,2-bis(diethylamino)-2,3-dinitro-1,3-butadiene, easily obtainable by ring-opening of 3,4-dinitrothiophene with diethylamine, and arylmethylmagnesium chlorides in THF at 0 degreesC furnished good yields of (E,E,E)-1,6-diaryl-3-nitro-1,3,5-hexatrienes. To explain the formation of the hexatrienes, a mechanism is advanced which involves, in particular, tautomerisation of the intermediate 1,6-diaryl-3,4-dinitro-2,4-hexadienes followed by base-induced elimination of nitrous acid. The electrocyclic disrotatory conversion of the hexatrienes into the corresponding 5,6-diaryl-2-nitro-1,3-cyclohexadienes was analysed by H-1 NMR spectroscopy and exploited for the high-yielding synthesis of 1,2-diaryl-4-nitrobenzenes employing, as oxidants, either DDQ or iodine in the presence of cyclohexene oxide as HI scavenger. (C) 2001 Elsevier Science Ltd. All rights reserved.