Nitrones and oxaziridines. XVI. Synthesis of 3-Hydroxyimino- and 3-Oxo-1-pyrroline 1-oxides by reductive cyclization reactions

1976 ◽  
Vol 29 (11) ◽  
pp. 2561 ◽  
Author(s):  
DSC Black ◽  
AB Boscacci
Keyword(s):  
Reductive Cyclization ◽  
Cyclization Reactions ◽  
Hydrolysis Of

5,5-Dimethyl-2-phenyl- (8a), 2-t-butyl-5,5-dimethyl- (8b) and 2,5,5- trimethyl- (8c) 3-oxo-1-pyrroline 1-oxides have been synthesized by hydrolysis of the respective 3-hydroxyimino-1-pyrroline 1-oxides,which have in turn been prepared by the sequential nitrosation and reductive cyclization of γ-nitrocarbonyl compounds.

Isocarbostyrils. II. The Conversion of 2-Methyl-4-acyl-5-nitroisocarbostyrils to 2-Substituted Indole-4-carboxylic Acids

1971 ◽  
Vol 49 (17) ◽  
pp. 2797-2802 ◽  
Author(s):  
D. E. Horning ◽  
G. Lacasse ◽  
J. M. Muchowski
Keyword(s):  
Sulfuric Acid ◽  
Carboxylic Acid ◽  
Carboxylic Acids ◽  
Alkaline Hydrolysis ◽  
Mannich Reaction ◽  
Reductive Cyclization ◽  
Acid Catalyzed ◽  
Acid Anhydrides ◽  
Hydrolysis Of ◽  
Derivatives Of

The sulfuric acid catalyzed acylation of 2-methyl-5-nitroisocarbostyril with carboxylic acid anhydrides gave the corresponding 4-acylated derivatives 3, which underwent reductive cyclization to 2-substituted derivatives of 4-methyl-1,3,4,5-tetrahydropyrrolo[4.3.2.de]isoquinolin-5-one (4). Alkaline hydrolysis of the six-membered lactam in 4 was accompanied by a retro-Mannich reaction to produce 2-substituted indole-4-carboxylic acids in about 40 % overall yield from 3.

Kinetics and mechanism of base-catalyzed cyclization of substituted amides and nitriles of hydantoic acid

1987 ◽  
Vol 52 (1) ◽  
pp. 140-155 ◽  
Author(s):  
Vladimír Macháček ◽  
Gabriela Svobodová ◽  
Vojeslav Štěrba
Keyword(s):  
Rate Constant ◽  
Acid Amide ◽  
Phenyl Group ◽  
Reaction Rate Constant ◽  
Amide Group ◽  
Cyclization Reaction ◽  
Hydrolysis Rate ◽  
Cyclization Reactions ◽  
Hydrolysis Of ◽  
Derivatives Of

Rates of base-catalyzed cyclizations of 8 substituted derivatives of hydantoic acid amide type R3-NH(5)-CO(4)-NR2(3)-CH2(2)-CO(1)-NHR1 and 9 nitriles type R3-NH(5)-CO(4)-NR2(3)-CHR1(2)-CN have been measured in aqueous and methanolic media. The cyclization of the amides in aqueous medium is also accompanied by hydrolysis of the hydantoins formed. In some cases the hydrolysis rate constant is greater than the corresponding cyclization reaction rate constant. With the least reactive amides, the cyclization is also accompanied by hydrolysis of the amide group. The rate of the cyclization reactions in water is higher than that in methanol (at the same concentration of the lyate ions) by the factor of 10-100. Substitution of hydrogen at 3 and 5 positions by methyl or phenyl groups causes an acceleration of the cyclization reaction, whereas a substitution in the amide group causes a considerable retardation. The greatest acceleration of the cyclization (by as much as 4 orders) is caused by introduction of phenyl group to the N(5) position, which is due to a substantial increase of concentration of the reactive anion.

Preparation of 1,3-thiazines: Sulphur analogues of nucleic acid pyrimidine bases

1970 ◽  
Vol 23 (1) ◽  
pp. 51 ◽  
Author(s):  
EN Cain ◽  
RN Warrener
Keyword(s):  
Acid Hydrolysis ◽  
Intramolecular Cyclization ◽  
Ring Closure ◽  
Synthetic Methods ◽  
Cyclization Reactions ◽  
Dithiocarbamic Acid ◽  
Pyrimidine Bases ◽  
Propiolic Acid ◽  
Hydrolysis Of ◽  
Acetylenic Acids

Sulphur analogues of uracil and thymine have been prepased, in which the N1 atom of the pyrimidine base has been replaced by a sulphur atom. A number of general synthetic methods are described for the synthesis of these 1,3-thiazines. The uracil analogues were prepared from the related 2-thio-1,3-thiazines, by acid hydrolysis of the 2-alkylthio derivative. 3,4-Dihydro-4-oxo-2-thio-2H-1,3-thiazine, its N-methyl and N-ethyl derivatives were obtained by cyclization of the addition compound resulting from the reaction of propiolic acid and the appropriate dithiocarbamic acid. The generality of this reaction, when propiolic acid is replaced with other acetylenic acids or their related esters, is discussed. The crystalline addition compounds obtained from dithiocarbamic acid and either propiolic acid or methyl propiolate were all shown by p.m.r, spectroscopy to have cis stereo-chemistry. The thymine analogues were prepared by an alternative route, which utilized the intramolecular cyclization of S-ethyl-N-(β-methoxymethacryloyl)dithiocarbamate to form 2-ethylthio-6-methyl-4-oxo-4H-1,3-thiazine, followed by acid hydrolysis of the 2-ethylthio group. Related intramolecular cyclization reactions of N-acyl-dithiocarbamates formed the 5-acetyl-, the 5-cyano-6-methyl-, the 5-cyano-6-ethyl-, and the 6-methyl-2-ethylthio-1,3-thiazine derivatives. A third approach involved the successful acid catalysed ring-opening-ring- closure of a. 4-oxo-2-thio-1,3-oxazine to the isomeric 2,4-dioxo-1,3-thiazine.

The Chemistry of Ethyl 2-Ethoxycarbonyl-5,5-Diphenylpenta-2,3,4-Trienoate, a Potential Precursor of Ph2c=C=C=C=C=O

1987 ◽  
Vol 40 (10) ◽  
pp. 1675 ◽  
Author(s):  
NR Browne ◽  
RFC Brown ◽  
FW Eastwood ◽  
GD Fallon
Keyword(s):  
Sulfuric Acid ◽  
Carboxylic Acid ◽  
Wittig Reaction ◽  
Cyclization Reactions ◽  
X Ray ◽  
X Ray Crystallography ◽  
Concentrated Sulfuric Acid ◽  
Triphenylphosphonium Bromide ◽  
Hydrolysis Of ◽  
Potential Precursor

The title diester , Ph2C=C=C=C( COOEt )2 (2), has been prepared by a Wittig reaction between (2-bromo-3,3-diphenylprop-2-en-1-yl) triphenylphosphonium bromide and diethyl 2-oxopropane-1,3-dioate ( mesoxalic ester). The diester (2) undergoes cyclization reactions in concentrated sulfuric acid to give diethyl 2-(3'-phenyl-1H-inden-1'-y1idene)propane-l,3-dioate (4) and triethyl 3-oxo-3',9-diphenyl-2,3-dihydrospiro[lH-fluorene-1,l'-[1H]indene]-2,2,4-tricarboxylate (6), the structure of which was determined by X-ray crystallography. The title diester (2)adds cyclopentadiene across the 2,3-C=C bond to give diethyl 3-(2',2'-diphenylethenylidene)bicyclo[2.2.l]hept-5-ene-2,2-dicarboxylate (10). Alkaline hydrolysis of diester (10) gives an unstable colourless acid and a stable yellow crypto acid shown by X-ray crystallography to be 3-(2',2'-diphenylethenyl)bicyclo[2.2.l]hepta-2,5-diene-2-carboxylic acid (12). Attempts to convert diesters (2) and acid (12) into derivatives suitable for pyrolytic generation of Ph2C=C=C=C=C=O failed; The mono-acid chloride (14) yielded a small phenylazulene fraction on pyrolysis at 780-800°/0.02 mm.

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