ISSN:
0941-1216
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Amino-thieno[2,3-c]pyrazoles and Amino-thieno[2,3-b]pyrrolesThe synthesis of thieno[2,3-c]pyrazoles and thieno[2,3-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-thieno[2,3-c]pyrazoles (9) if the position 1 is alkylated (8). Acetyl acetone yields 2-mercapto-pyrazolo[1,5-a]pyrimidine (5). After S-alkylation (10a-d) are immediately cyclized to thieno [2′,3′:3,4]pyrazolo[1,5-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-imidazo[1,2-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-thieno[2,3-b]pyrroles (18a-b) arise. Reaction of 5-amino-2-alkylthio-pyrrol-3,5-dicarbonitrile (17) with acetyl acetone provides pyrrolo[1,2-a]pyrimidine (20a-c) which can be cyclized to form thieno[3′,2′:4,6]pyrimidines (21a-c) very easily.
Additional Material:
6 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/prac.199533701101
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