Flash vacuum pyrolysis 1.2.3- thiadiazoles

Without additional reagents Thioketenes from 1,2,3-thiadiazoles Flash vacuum pyrolysis... 

Flash-vacuum pyrolysis at 550 °C/0.08 Torr of 2-(dimethylamino)-5-phenyl-6//-l,3,4-thiadi-azin-6-ones results in thermal fragmentation with formation of the corresponding N,N-dimethyl-5-phenyl-l,3,4-thiadiazol-2-amine together with dimethylcyanamide and benzo-nitrile.92... 

The Diels-Alder reaction of thioketenes with cyclopentadiene and 2,3-dimethylbutadiene proceeds across the C=S bond of the thioketene to give the adducts in high yields. For example, trapping of dichlorothioketene, obtained in the flash vacuum pyrolysis of its dimer, with cyclopentadiene in an argon matrix at -196 °C, affords the [4-1-2] cycloadduct ". Also, pyrolysis of 5-isopropyl-4-phenyl-1,2,3-thiadiazole at 530 C and trapping of the thioketene 83 with cyclopentadiene gives a quantitative yield of the [4-1-2] cycloadduct 84 . ... 

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