UNSYMMETRICALLY SUBSTITUTED 3,3′-METHYLENE BRIDGED 2,2′-DIHYDROXYCHROMONES

Unsymmetrically substituted dicoumarol derivatives have been synthesized by taking advantage of the fact that 4-hydroxycoumarins will undergo the Mannich reaction at C3 and also take part in Michael-type addition reactions. In the presence of methyl iodide, 4-hydroxy-3-N-piperidinomethylcoumarin and 4-hydroxycoumarin gave dicoumarol. By using monosubstituted 4-hydroxycoumarins a variety of unsymmetrically substituted dicoumarols have been prepared in good yield. The infrared spectra of some of the intermediates and products are reported and discussed.

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A Convenient One-Pot Synthesis of Pyrazolo[3,4-d]pyrimidines and s-Triazolo[3,4-b][1,3,5]thiadiazines

Zeitschrift für Naturforschung B ◽

10.1515/znb-1997-1119 ◽

1997 ◽

Vol 52 (11) ◽

pp. 1401-1412 ◽

Cited By ~ 18

Author(s):

Zeinab A. Hozien ◽

Abd El-Wareth A. O. Sarhan ◽

Hassan A. H. El-Sherief ◽

Abdalla M. Mahmoud

Keyword(s):

Mannich Reaction ◽

Aromatic Amines ◽

Good Yield ◽

Room Temperature ◽

Secondary Amines ◽

One Pot ◽

Aminomethyl Derivatives ◽

Primary Aromatic Amines ◽

The Mannich Reaction ◽

Primary Aliphatic Amines

Abstract The reaction of 5-amino-3-aryl-1-phenylpyrazoles (1a-d) with formaldehyde and secondary amines in boiling ethanol gave the corresponding 4-alkylaminomethyl derivatives (2a-f) and bis-(4-pyrazolyl)methane (4a,b) as byproduct. Such reaction with primary aliphatic and aro matic amines at room temperature afforded 1,3,5-trisubstituted (5a-h) and 1,3.5,7-tetrasubstituted tetrahydropyrazolo[3,4-d]pyrimidines (8a-k) respectively in good yield. Similarily, the Mannich reaction of 5-mercapto-3-phenyl-1,2,4-triazole (9) with secondary amines, in boiling ethanol, and primary aromatic amines, at room temperature, gave 2 -substituted aminomethyl derivatives (10a-c) and (14a-g) respectively,while with primary aliphatic amines, p-toluidine and p-anisidine,at room temperature,and with other primary aromatic amines, in boiling ethanol, afforded the cyclized products 12,4-triazolo[3,4-b]thiadiazines (13a-e); (15f,g) and (15a-e), respectively.

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2-Naphthol-pyrazole conjugates as substrates in the Mannich reaction

Zeitschrift für Naturforschung B ◽

10.1515/znb-2017-0209 ◽

2018 ◽

Vol 73 (5) ◽

pp. 275-280

Author(s):

Gheorghe Roman

Keyword(s):

Methyl Iodide ◽

Mannich Reaction ◽

Benzyl Chloride ◽

Pyrazole Ring ◽

The Mannich Reaction ◽

Chloride Methyl

AbstractSeveral novel 2-naphthol-pyrazole conjugates have been synthesized through the O-alkylation of 1-[(3,5-dimethyl-1H-pyrazol-1-yl)methyl]naphthalen-2-ol with methyl iodide, benzyl chloride, methyl bromoacetate and N-benzyl-2-bromoacetamide. The aminomethylation of these 2-naphthol-pyrazole conjugates has been examined employing the classical conditions for the Mannich reaction, and also by using N,N-dimethylmethyleneiminium chloride as preformed aminomethylating reagent. In both situations, aminomethylation of these substrates occurred at C-4 of the pyrazole ring. The bifunctional substrate 1-[(3,5-dimethyl-1H-pyrazol-1-yl)methyl]naphthalen-2-ol has been chemoselectively aminomethylated in the pyrazole ring using the same preformed aminomethylating reagent.

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