Ute Hain

Zur Chemie der 4-Aminothiazolin-2-thione

Abstract4-Aminothiazolin-2-one-hydrazones3 are obtained by succesive treatment of the title compound1 with dimethyl sulfate and hydrazinehydrate. The rearrangement of 4-aminothiazolin-2-ylidenmalononitrile7 derived from1 yields the 2,4-diamino-thiophene derivatives8. Analogously, the 4-aminothiazolin-2-yliden-cyanamides10 react to form the substituted 2,4-diaminothiazoles11. Succesive reaction of the ethyl (4-amino-2-thioxo-thiazolinyl-3)-acetates12 with dimethyl sulfate and malononitrile yields the 3,6-diamino-pyrrolo[2,1-b]-thiazoles14.

Enantioselective synthesis of (S)- and (R)-6-hydroxy-8-nonene-carboxylates by asymmetric catalysis: a formal synthesis of (R)-α-lipoic acid and its (S)-antipode

Abstract A short and efficient enantioselective synthesis of (S)- and (R)-configured 6-hydroxy-8-nonene-carboxylates — precursors to (R)-α-lipoic acid and its (S)-enantiomer — by allylation of alkoxycarbonyl substituted aldehydes with allyltrimethylstannane and BINOL/Ti(OiPr)4 catalyst is described. The best results in terms of enantiomeric purity and yield are obtained employing 10 mol% of the titanium-species without molecular sieves.

Substituierte 3-Amino-thiophene und 3-Amino-selenophene aus β-Chlor-α-cyan-zimtsäurenitril

Summaryβ-Chloro-α-cyano-cinnamonitrile (1) reacts in one step with α-oxo-thioles3 or successively with sodium sulphide and α-chlorocarbonyl compounds4 to form the 5-substituted 4-amino-2-phenyl-thiophene-3-carbonitriles5. Analogously, the successive reactions of β-chloro cinnamonitrile1 with sodium selenide — produced in situ from selene and sodium boronhydride — and α-chlorocarbonyl compounds4 yields the 5-substituted 4-amino-2-phenyl-selenophene-3-carbonitriles6.

Zur Ringumwandlung von 2-Amino-thiophen-3-carbonsäureestern: Pyridon- und Pyridazinon-Derivate

Whereas treatment of the ethyl 5-acetyl-2-amino-4-methyl-thiophene-3-carboxylate (1) with potassium hydroxide yields the 2-hydroxy-thiophene-3-carbonitrile4 its hydrazone2 is converted into the 1-amino-5-mercapto-2-pyridone derivative6. The transformation of the 2-amino-5-phenylazo-thiophene derivative9 by potassium hydroxide yields the substituted 3-mercapto-pyridazin-6(1H)one10, with sodium ethoxide the 5-phenylhydrazono-2-oxo-thiolen-3-carbonitrile11 is formed. From6 the 5-mercapto-2-pyridone derivatives7 d,e can be obtained.

Zur Chemie der 4-Amino-thiazolin-2-thione, 2. Mitt.

Summary6-Amino-thiazolo[4,5-c]isothiazole derivatives4 are obtained by addition of hydrogen sulfide to the 4-Amino-thiazoline-5-carbonitrile2 followed by cyclooxidation of the intermediate thioamides3. In the presence of sodium sulfite the hydrolysis of the4-amino-2-methylthio-thiazolium salts5 derived from the title compounds1 yields the4-amino-thiazolin-2-ones6. By their further hydrolysis the 2,4-dioxo-thiazolidin-5-carboxamides8 are formed. The 2-oxo-and 2-thioxo-thiazolo [4,5-d]pyrimidin-7-ones and -thiones available from1 undergo ring opening by hydrolysis to give the substituted 4-amino-6-oxo- and 4-amino-6-thioxo-pyrimidine-5-thiols15a–h and13i–e. They have been isolated as their disulfides14 or 5-alkyl derivativesi.e. the substituted 4-amino-5-alkylthiopyrimidin-6-ones and -thiones16. In analogy, the intermediate 6-amino-7-oxo-thiazolo[4,5-d] pyrimidin-2-thione18 and the 7-amino-thiazolo[4,5-d]-pyrimidin-2-thione24 derived from1 react by ring cleveage to yield the 1,4-and 4,6-diamino-pyrimidin-5-thiole derivatives22 and27, respectively, isolated as their disulfides or alkylthio-derivatives. From the pyrimidine16b the pyrimido[5,4-b]1,4-thiazine derivative18 can be obtained.