Orthoamide. IL. Umsetzungen von Orthoamid-Derivaten mit Schwefel und Selen, Synthesen von 1,3-Thiazol- und 1,3-Selenazolderivaten

Abstract

Orthoamides. IL. Reactions of Orthoamide Derivatives with Sulfur and Selenium, Syntheses of 1,3-Thiazole- und 1,3-Selenazole Derivatives N,N-Dimethylformamide acetal reacts with elemental selenium to give a mixture of selenocarbonic acid derivatives 2 and 3, which can be converted to the pure N,N-dimethylcarbamidic acid Se-methylester 2 by treatment with methyl iodide. Analogously from the orthoformic acid derivatives 5 and 6 and selenium the N,N,N′,N′-tetramethyl-selenurea 7 can be prepared. In the reaction of 12 with elemental sulfur and selenium the amidines 14 and 15, respectively, are formed. By treatment of 14 and 15 with α-halogenated carbonyl compounds and triethylamine the 1,3-thiazoles 18 and 1,3-selenazoles 19 can be prepared. The synthesis of the propynoic acid orthoamide 26b is described. 26b reacts with the guanidinium salt 24b to give the bis-orthoamide of butynedioic acid 20b. Other orthoamides of butynedioic acid 20b–20e can be synthesized from the orthoamide 20a by transamination. The thiolation of the orthoamides affords the bisamidinium-dithiolates 21a–c, which can be alkylated to give the bisamidinium salts 27. By treatment with α-halogene carbonyl compounds and triethylamine the dithiolates 21a–c are cyclized to give thieno [3,2b] thiophenes 28a–n. The quadrupoles 21 undergo cycloadditions with dimethyl-butynedioate which afford the bis(3H-thiophene-2-ylidenes) 29a–c. Treatment of 29a with methyl tosylate gives rise to the dithiophene 30a. The dithiophene 30b can be obtained by heating 21b with dimethylbutynedionate.