Cycloamination strategies for renewable N-heterocycles

Publisher Summary 1,2,4-Triazolo[1,5-a]pyrimidines (TPs) play an important role in pharmaceutics, agrochemistry, photography, and other fields. They attract attention in synthetic, analytical, and theoretical chemistry. Isomeric 1,2,4-triazolo[4,3-a]pyrimidines and partially reduced TPs are mentioned only when they are precursors, potential intermediates, or reaction products of TPs. By far, the most TP syntheses are condensations of dinucleophilic 5-amino-1,2,4-triazoles (ATs) with 1,3-bifunctional synthons as in the formation of TP 2. Quantum-chemical calculations on TPs, particularly oxo compounds, were performed by several groups. A new aromaticity index was calculated for heterocyclic compounds. Comparison of the index of 2-ribosyl-5,7-dimethyl TP with that of the isomeric compound suggests that the driving force for the Dimroth rearrangement of the latter substance is the increase in aromatic character. The chapter discusses the molecular dimensions, molecular spectra, thermodynamic properties, tautomerism, and betain and mesoionic structures of TPs. The reactivity of TPs are described including triazolopyrimidines as bases and acids, ring alkylation, electrophilic reactions at carbon ring atoms, nucleophilic addition, ring cleavage, nucleophilic substitution of functional groups at the rings introduction and transformation of individual substituents, and reactivity of side chains. The pharmaceutical and agrochemical uses are described. The uses in information recording are also discussed.

Recent Progress in 1,2,4-Triazolo[1,5-a]pyrimidine Chemistry

Catalytic hydrogenation in organic synthesis - procedures and commentary

2‐C‐Formyl Glycals: Emerging Chiral Synthons in Organic Synthesis

Design and synthesis of pyrimidine molecules endowed with thiazolidin-4-one as new anticancer agents.

The ring transformations of 2-formylglycals with 2-cyano-N-(4-methoxyphenyl)acetamide, 2-benzimidazolylacetonitrile, 2-nitromethylbenzimidazole yielded 5-(1,2,4-tri-O-benzyl-D-arabino/lyxo-1,2,3,4-tetrahydroxybutyl)-1,2-dihydro-1-(4-methoxyphenyl)-2-oxopyridine-3-carbonitriles (2), 2-(1,2,4-tri-O-benzyl-D-arabino/lyxo-1,2,3,4-tetrahydroxybutyl)benzo[4,5]imidazo[1,2-a]pyridine-4-carbonitriles (3) and 2-(1,2,4-tri-O-benzyl-D-lyxo-1,2,3,4-tetrahydroxybutyl)-4-nitrobenzo[4,5]imidazo[1,2-a]pyridine (4), respectively.

Ring Transformations of 2-Formylglycals with C,N-Dinucleophiles

A Facile Synthesis of Acyclo-C-nucleoside Analogues from 2(3)-Formylglycals

The synthesis of steroidal heterocycles containing the pyrazole and pyrimidine ring fused to the 16,17-position of the steroid nucleus is reported. Androstenolone acetate (1) reacted with carbon disulfide, iodomethane and sodium hydride to furnish 3β-acetoxy-16-[bis(methylthio)methylene]-5-androst-5-en-17-one (2). The reactions of 2 with hydrazine hydrate and methylhydrazine afforded the 5’-methylthio- pyrazolo[4’,3’:16,17]androst-5-en-3β-ols 3a and 3b, respectively. Treatment of 2 with amidinium, guanidinium, and isothiuronium salts in the presence of sodium methoxide yielded the 6’-methoxy-pyrimido[5’,4’:16,17]androst-5-en-3β-ols (4a-4e).

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Alina Montero

Papers

Ring Transformations of 2-Formylglycals with C,N-Dinucleophiles

A Facile Synthesis of Acyclo-C-nucleoside Analogues from 2(3)-Formylglycals

Synthesis of New Pyrazole and Pyrimidine Steroidal Derivatives

Synthesis of precursors for new pyrimidine acyclo-c-nucleoside analogues by ring transformation of 2-formylgalactal *,†

Synthesis of Substituted 1‐\C\‐Phenyl‐D‐Tetritols and 1‐C‐(1H‐Pyrazol‐4‐yl)‐D‐tetritols by Ring Transformation of 2‐Formylglycals