Studies on Vitamin B<SUB>1</SUB> and Related Compounds.CVII.Synthesis of Hydroxyethylthiamine Homologs
作者:Yoshikazu Oka、Eiko Imamiya、Hiroshi Hirano
DOI:10.1248/cpb.15.448
日期:——
Two types of dihydrothiamine derivatives, IV, VI, VIII, and V, VII, IX, were obtained by the reaction of I, II, and phenylglyoxal derivatives. On treatment with mineral acids both of those underwent hydrolysis in the presence of water, but in non-aqueous solutions thiamine was afforded under room temperature. Treatments of them with weak acids such as phosphoric acid, formic acid and acetic acid effected the conversion to the aryl homologs of hydroxyethylthiamine, XI, XII and XIII.
Preparation of Axially ChiralN,N′-Diarylimidazolium andN-Arylthiazolium Salts and Evaluation of Their Catalytic Potential in the Benzoin and in the Intramolecular Stetter Reactions
作者:Jens Pesch、Klaus Harms、Thorsten Bach
DOI:10.1002/ejoc.200300762
日期:2004.5
imidazolium salts 15b, the thiazolium salts proved to be suitable catalysts in the benzoin condensation of benzaldehyde (1 2) and in the intramolecular Stetter reaction of the α,β-unsaturated ester 9a. The best results obtained with catalyst 19 (20 mol %) were 85% yield of product 2 (40% ee) and 75% yield of product 10a (50% ee). The stereogenic axis of catalyst 19 is not configurationallystable in the
Synthesis and structure of bridged thiazolium salts
作者:Finian J. Leeper、David H.C. Smith
DOI:10.1016/s0040-4039(00)80289-0
日期:1988.1
Bridged thiazoliumsalts (6a,b) have been synthesized using macrolactonisation techniques to make the corresponding thiazolinethiones (4a,b) followed by treatment with H2O2. For each compound the bridge exists predominantly in a single conformation which has been determined both by n.m.r. and X-ray crystallography.
已使用大环内酯化技术合成了桥接的噻唑鎓盐(6a,b),以制备相应的噻唑啉硫酮(4a,b),然后用H 2 O 2处理。对于每种化合物,桥主要存在于单一构象中,该构象已通过nmr和X射线晶体学确定。
Synthesis of 3-deazathiamine
作者:Daniel Hawksley、David A. Griffin、Finian J. Leeper
DOI:10.1039/b006962k
日期:——
An efficient ten-step synthesis of deazathiamine is described. The synthesis starts from commercially available α-acetyl-γ-butyrolactone and proceeds via deamination of the key aminothiophene 6. The Gewald synthesis of thiophenes is shown to give a mixture of isomeric products with the unsymmetric ketone used here and so a modified procedure giving a single isomer is developed.
Novel sulphur containing food flavor substances are provided containing an oxygen or sulphur atom in a five or six membered ring structure, one alkyl or hydroxy alkyl substituent at at least either of the carbon atoms adjacent to the hetero atom and having at least one sulphur or oxygen atom attached to another carbon atom of the ring structure.