SYNTHETIC EXPLOITATION OF THE RING-OPENING OF 3,4-DINITROTHIOPHENE - ACCESS TO 1,4-DISUBSTITUTED 2,3-DINITRO-1,3-BUTADIENES AND 2,3-DIAMINOBUTANES

The reactions of 1,4-bis(diethylamino)-2,3-dinitro- 1,3-butadiene 1 (d eriving from ring-opening of 3,4-dinitrothiophene with diethylamine) w ith one mole of Grignard reagents give, together with disubstituted pr oducts 1,4-dialkyl- and 1,4-diaryl-2,3-dinitro-1,3-butadienes 2, the m onosubstituted 1-alkyl-4-diethylamino- and 1-aryl-4-diethyl-amino-2,3- dinitro-1, 3-butadienes 8 in yields dependent on the nature of the rea gent employed. Aryl-substituted compounds 8 undergo a highly regiosele ctive reaction with aryl Grignard reagents to furnish good yields of 1 -Ar-1-4 Ar-2-2,3-dinitro-1,3-butadienes 9. Preliminary results are als o reported on the transformation of some dinitrobutadienes 2 and 9 int o the corresponding 1,4-disubstituted 2,3-diaminobutanes 10.