13732-33-7Relevant articles and documents
Molecular design of pyrazolo[3,4-d]pyridazines
Matiichuk,Potopnyk,Obushak
experimental part, p. 1352 - 1361 (2009/09/06)
Reactions of arenediazonium chlorides with ethyl 2-methyl-and 2-chloro-4-oxobutanoates gave, respectively, ethyl 2-(arylhydrazono)propanoates and chloro(arylhydrazono)acetates. Ethyl 2-(arylhydrazono)-propanoates reacted with the Vilsmeier-Haak reagent to give ethyl 1-aryl-4-formyl-1 H-pyrazole-3-carboxylates. Ethyl 1-aryl-4-acetyl-5-methyl-1H-pyrazole-3- carboxylates were obtained by reaction of chloro(arylhydrazono) acetates with acetylacetone. Reactions of the obtained pyrazole derivatives with hydrazine and methylhydrazine led to the formation of the corresponding 3,4-R 2 1 -6-R2-2-aryl-2,6-dihydro-7H-pyrazolo-[3,4-d]pyridazin-7- ones (R1, R2 = H, Me) which were subjected to alkylation and sulfurization.
Both enantiomers of N-Boc-indoline-2-carboxylic esters
Kurokawa, Masayuki,Sugai, Takeshi
, p. 1021 - 1025 (2007/10/03)
An immobilized form of Candida antarctica lipase (Chirazyme L-2) catalyzed enantioselective hydrolysis (E > 1000) of N-Boc-indoline-2-carboxylic acid methyl ester. The reaction proceeded efficiently at 60 °C, a temperature over the melting point of substrate, in the conversion of 49.9% to provide the hydrolyzed product, (S)-carboxylic acid with >99.9% ee and the unreacted (R)-ester with 99.6% ee. A newly developed expeditious route to the racemic substrate (a total of six steps, 60% yield), starting from aniline and ethyl α-methylacetoacetate, established the scalable chemoenzymatic synthesis of the desired compounds in both enantiomerically pure forms.
Geometrical Isomerism of Phenylhydrazones of α-Keto Esters. II. p-Substituted Phenylhydrazones of Ethyl Pyruvate and 2,4-Dinitrophenylhydrazones of Some α-Keto Esters
Ishibashi, Fumihide,Nashima, Takeo,Nishino, Junko,Kobayashi, Ikuko,Ichihara, Yoshinori,et al.
, p. 73 - 76 (2007/10/02)
Each geometrical isomer of various substituted phenylhydrazones of ethyl pyruvate and 2,4-dinitrophenylhydrazones of some α-keto esters was isolated in a pure state.Partial isomerizations of the E-isomers of the former hydrazones to the Z-isomers took place by keeping solutions of the hydrazones in organic solvents containing C, H, and Cl in the dark.An E- or Z-structure was assigned to each molecule on the basis of IR and 1H NMR spectra.In all cases, isomers with higher Rf -values on a silica gel TLC (using benzene as a developing solvent) involved an intramolecular hydrogen bonding between the imino hydrogen and the ester carbonyl oxygen.Thus, the Z-structure was assigned.An E-structure was assigned to other isomers with lower Rf-values.The present assignment is, thus, entirely the same as that proposed in a previous investigation.
