Volume 17, Issue 5-6

A novel tridentate chiral imidazolium hexafluorophosphate, a precursor for N -heterocyclic carbene (NHC) ligand, was synthesized from (S)-proline in five steps in 24% overall yield. The compound was characterized by NMR and elemental analysis. Its molecular structure was determined by X-ray diffraction analysis. This chiral compound has two stereogenic centers which are within two chelating side chains and its specific rotation is -19.6°.

New coumarin heteroanalogs were synthesized by condensation of 2-amino-4-aryl-3-cyano-5-oxo-4 H ,5 H -pyrano-[3,2- c ]chromenes and 1,3-cyclohexanedione in 35–78% yield.

Condensation of 8-formyl-7-hydroxy chromones 2a–e with methyl vinyl ketone and acrylonitrile in the presence of diazabicyclo[2.2.2]octane (DABCO) under Baylis-Hillman reaction conditions afforded 9-cyano/acetyl-substituted pyrano[2,3- f ]chromones 3a–e and 4a–e .

A one-pot, three-component reaction of an aromatic aldehyde, malononitrile and 3-methyl-1-phenyl-2-pyrazolin-5-one in the presence of a catalytic amount of trichloroacetic acid produces a 6-amino-4-aryl-5-cyano-3-methyl-1-phenyl-1,4-dihydropyrano[2,3- c ]pyrazole in excellent yield and in a short reaction time.

Novel thiazolo[2,3- b ]quinazolines were prepared by the cyclization reaction between octahydroquinazoline-2-thiones with α- bromoketones, which provides a readily accessible multifunctionalized quinazoline template for diversity-oriented synthesis.

A series of pyrido[2,3- b ]indole derivatives was synthesized via a novel multicomponent reaction catalyzed by ferric hydrogen sulfate.

Green chemistry metrics (E-factor, atom economy, reaction mass efficiency) and the EcoScale have been compared for conventional heating and microwave assisted bromination and nitration of bis-pyrazolo[3,4-b;4′,3′- e ]pyridines. The major advantages in microwave-assisted reactions in relation to traditional evaluation of the process have encompassed higher yields, shorter reaction time and higher selectivity. The microwave-assisted reactions have shown better green chemistry parameters and EcoScale ranks than those in conventionally heated reactions. Mass reaction efficiency values have been critical for considering ‘green’ the reactions conducted under traditional conditions. Additional advantages of using microwaves, not considered in calculated parameters, include easier purification of the reaction mixture and isolation of the product.

7-Benzyl-5,6,7,8-tetrahydropyrido[4′,3′:4,5]thieno[2,3- d ]pyrimidin-4(3 H )-ones were synthesized by base catalyzed reactions of nucleophilic reagents (aliphatic amines, alcohols or phenols) with carbodiimides 4 , which in turn were obtained by the aza-Wittig reaction of iminophosphoranes 3 with aromatic isocyanates.

A mixture of ethyl 4-(2-nitrophenyl)butenoates undergoes an unusual intramolecular cyclisation in the presence of a catalytic amount of potassium tert -butoxide.

1-[(5-Chloro-1 H -indol-2-yl)carbonyl]-4-methylpiperazine (JNJ 7777120) is the known histamine H 4 receptor reference compound. The convenient way of its synthesis and the crystal structure are described.

New triazolothiadiazoles bearing L -amino acid moieties were synthesized by reaction of 4-amino-5-phenoxy-4 H -1,2,4-triazole-3-thiol with L -amino acids in the presence of phosphorus oxychloride.

The reaction of diphenyldiazomethane with N -substituted maleimides produces Δ 1 -pyrazolines. The photolysis of Δ 1 -pyrazolines leads to cyclopropanes.

A series of 1-[(1,3-thiazol-2-ylamino)methyl]-2-naphthols were synthesized via one-pot three-component Mannich reaction of 2-aminothiazoles, aldehydes and 2-naphthol under solvent-free conditions. This protocol has advantages of no use of volatile organic solvents and hazardous catalysts. Work-up procedure is simple and yields are high.

A simple and efficient synthesis of 2,4,5-triarylimidazoles and 2-arylphenanthrimidazoles was developed using the one-pot, three-component condensation reaction of an aromatic aldehyde, benzil or 9,10-phenanthroquinone and ammonium acetate in refluxing ethanol in the presence of the catalyst sulfamic acid.

Single isomers of the furanylidene system 8 were synthesized in four steps. The synthesis begins with the dianion of β-keto carbonyls and culminates in a mild, tandem desilylation-cyclization reaction using tosylic acid. Compounds synthesized in this study have the potential for further diversification at the alkyne, carbonyl and enol-ether moieties. Hence, the furanylidenes from this study are prospective building blocks for biologically active, furan-containing natural products and their analogs.