Amino-thieno[2,3–c]pyrazole und Amino-thieno[2,3–b]pyrrole

Amino-thieno2,3–c]pyrazoles and Amino-thieno2,3–b]pyrroles The synthesis of thieno2,3–c]pyrazoles and thieno2,3–b]pyrroles is described. From the dithioliumsalt ( 1 ) and potassium hydroxide the potassium-(2,2-dicyan-1-methylthio-ethen-1-yl)-thiolate ( 2 ) is formed. This reacts with hydrazine hydrate to form the 3-amino-5-thioxo-pyrazol-4-carbonitrile ( 3 ) S-Alkylation with α-chlorocarbonyl compounds yielding ( 6a–c ) leads via Thorpe-Ziegler-cyclization to 3,4-diamino-thieno2,3–c]pyrazoles ( 9 ) if the position 1 is alkylated ( 8 ). Acetyl acetone yields 2-mercapto-pyrazolo1,5–a]pyrimidine ( 5 ). After S-alkylation ( 10a–d ) are immediately cyclized to thieno 2′,3′:3,4]pyrazolo1,5-a]pyrimidine ( 11a–d ). The ketone ( 6a ) can be cyclized to the pyrazolo 5,1–b]thiazole ( 12 ). 3 reacts with oxalyl chloride to form the 2,3-dioxo-6-thioxo-imidazo1,2-b]pyrazole ( 13 ) of which S-phenacyl derivative ( 14 ) because the NH-proton cannot be cyclized. The 5-amino-3,4-dicyano-pyrrol-2-thiolate ( 16 ) shows the analogous behaviour. The S-alkylation is followed by cyclization, and 3,5-diamino-thieno2,3–b]pyrroles ( 18a–b ) arise. Reaction of 5-amino-2-alkylthio-pyrrol-3,5-dicarbonitrile ( 17 ) with acetyl acetone provides pyrrolo1,2-a]pyrimidine ( 20a–c ) which can be cyclized to form thieno3′,2′:4,6]pyrimidines ( 21a–c ) very easily.