Novel cycloaddition products from the reaction of 2,5-dichloro-1,1,1,6,6,6-hexafluoro-3,4-diazahexa-2,4-diene with cycloalkenes, cyclodienes and cycloheptatriene, and of hexafuoroacetone azine with cycloheptatriene

Abstract

Thermal reaction (20–70 °C) of the dichloroazine CF 3CCl=NN=CClCF 3 ( 2) with cyclopentene (in CH 2Cl 2 solvent), cycloheptene, indene, acenaphthylene, 2,3-dihydrofuran, 2,3-dihydropyran, norbornadiene, cyclopentadiene and dicyclopentadiene gives as the major product in each case the rearranged [3+2] cycloadduct ( 3) containing a CF 3CCl 2 group; hydrolysis (CF 3CCl 2 → CF 3CO) to give the amide ( 4) takes place on attempted chromatographic purification on silica gel. With cyclopentene the rearranged cyclopentadiene [3+2] cycloadduct ( 3b) is also formed, while other products obtained by chromatographic separation from the 2,3-dihydropyran reaction are the 5,6-dihydropyran-3-yl azine ( 5), the hydrazone CH 2(CH 2) 2OCHCC(CF 3)NNH 2 ( 8) and quimolar quantities of 5,6-dihydropyran-3-yl trifluoromethyl ketone ( 6) and the chlorohydrazone O(CH 2) 4CHNHNCClCF 3 ( 7) possibly arising via hydrolysis of the 1:2 adduct ( 16). The reaction of azine 2 with cycloheptatriene at 70 °C gives a complex mixture, in which the major products are the rearranged [3+6] cycloadduct ( 31) and the dehydrochlorinated [3+2] cycloadducts ( 10) and ( 11) containing a CF 3CHCl group. The corresponding reaction with hexafluoroacetone azine ( 1) at 70 °C affords the criss-cross [3+2] cycloadduct ( 22), the bis-ene adduct ( 23) and its oxidation product, the azo compound ( 24), and the [3+6] cycloadduct diaziridine ( 25).