Convenient synthesis of 4-trifluoromethyl-substituted imidazole derivatives

Mesoionic 4-trifluoroacetyl-1,3-oxazolium-5-olates (1), obtained from the reaction of N-acyl-N-alkylglycines (2) with trifluoroacetic anhydride, react with ammonia to give 4-trifluoromethyl-3,4-dihydroimidazoles (3) in high yields. Dehydration of 3 gives 4-trifluoromethylimidazoles (4) in high yields. The novel ring transformation of 1 into 3 occurs via a regioselective attack of ammonia on the C-2 position of the ring.     

A convenient and rapid approach for the synthesis of 1-benzyl-3-heterocyclic pyrazoles

A variety of 1-benzyl-3-heterocyclic pyrazoles were rapidly assembled by a two-step N-benzylation/Suzuki coupling sequence. A one-pot variation of this sequence is demonstrated.     

Application of Tsunoda reagent to the convenient synthesis of drug-like pyrazoles

The versatility of the under-utilised (cyanomethylene)tributylphosphorane (CMBP, Tsunoda reagent) was demonstrated on two occasions in a drug discovery context. Firstly, the high reactivity of the phosphorane allowed the alkylation of a weakly acidic pyrazole when standard Mitsunobu conditions were unsuccessful. Secondly, the clean reaction profile generally obtained using CMBP allowed the direct use of the crude mixture in a subsequent Suzuki cross coupling. This reagent has utility when isolation of the Mitsunobu reaction product (e.g. containing a boronate) is not desirable.     

Methyl 4-toluenesulfonyloxymethylphosphonate, a new and versatile reagent for the convenient synthesis of phosphonate-containing compounds

A straightforward procedure leading to the new phosphonylating reagent, methyl 4-toluenesulfonyloxymethylphosphonate, requiring no chromatographic purification is described. This stable reagent works with the same efficiency as dimethyl and other dialkyl esters for the introduction of an O-phosphonomethyl moiety while, in contrast to dimethyl ester, it does not cause any unwanted methylation of sensitive functionalities. Its utility for the alkylation of protected nucleosides in high yield is exemplified.     

A convenient synthesis of 4-alkyl-5-aminoisoxazoles

[reaction: see text] A series of 4-alkyl-5-aminoisoxazoles have been synthesized in high yield by nucleophilic addition of lithiated alkyl nitriles to (alpha)-chlorooximes. The scope and limitations of this reaction were examined by varying the nature of the nitrile and chloride oxime.     

A convenient synthesis of 4-alkoxy- and 4-hydroxy-2,6-difluoroanilines

Two independent synthetic pathways for the preparation of 4-methoxy, 4-benzyloxy and 4-hydroxy-2,6-difluoroanilines, versatile building blocks in medicinal chemistry, based on diazonium coupling or Curtius-type rearrangements are presented.     

A convenient synthesis of cis and trans 4-tert-butoxycarbonyl-substituted cyclohexylglycine

A novel synthesis of cis and trans substituted 4-tert-butoxycarbonyl cyclohexylglycines via asymmetric aminohydroxylation of vinyl styrene followed by reduction of the aromatic ring and subsequent oxidation is reported.     

A convenient synthesis of 4-aminoaryl substituted cyclic imides

An efficient one-step synthesis of 4-nitro-N-aryl substituted glutarimides, succinimides and maleimides in polyphosphoric acid is described together with the subsequent reduction to the corresponding anilines. The scope and limitation of this cyclocondensation are presented.     

A new versatile synthesis of 4-substituted diaminopyridine derivatives

A new convenient method for the synthesis of substituted 2,6-diacetamido pyridines has been developed. It starts from 4-hydroxypyridine and comprises the introduction of the amino groups by the Chichibabin reaction. After several protection and deprotection steps 2,6-diacetamido-4-hydroxy pyridine is obtained, which is regarded as a key compound for the synthesis of various substituted 2,6-diacetamido pyridines. It is shown that the free hydroxy group is susceptible for nucleophilic substitution. This provides an easy access to the introduction of different functional groups at 4-position of 2,6-diacetamido pyridine. The advantages over other procedures described in the literature are discussed.     

Mild, convenient and versatile Cu-mediated synthesis of N-aryl-2-imidazolidinones

A mild, general, convenient and practical methodology for the selective copper-mediated mono N-arylation of unprotected 2-imidazolidinone was developed. Strong electron-donating groups and free hydroxy and amino groups on the aryl iodide substrates were well tolerated. The use of n-butanol as the solvent for the copper-catalysed mono-arylation of 2-imidazolidinone is unprecedented.     

A convenient synthesis of 1,3-oxazolidin-4-ones and 1,3-oxazin-4-ones

1,3-Oxazolidin-4-ones and 1,3-oxazin-4-ones were synthesized by formal cyclocondensation of imines with α- or β-hydroxy acids.     

2－芳胺基－2－硒唑啉－4－酮的简便合成

芳基硒脲与溴乙酸乙酯在乙醇溶液中作用，可合成得到含硒杂环化合物2-芳胺 基-2-硒唑啉-4-酮，反应产率为71%。     

A convenient synthesis of 4-amino-3,5-dialkyl-4H-1,2,4-triazoles

Ester tert-butoxycarbonylhydrazones 2 were reacted with some carboxylic acid hydrazides to give 4 -terrtutoxycarbonylamino-3,5-dialkyl-4H-1,2,4-triazoles 3–6 . Treatment of 3–5 with 6 N hydrochloric acid under mild conditions resulted in the formation of 4-ammo-3,5-dialkyl-4H-1,2,4-triazole hydrochlorides 7–9 in good yields. Compound 7a was converted to the free 4 -amino compound 10a upon treatment with ethanolic sodium ethoxide solution.     

A new convenient synthesis of functionalized 2,3-dihydro-4-pyridones

A simple, efficient and diastereoselective route to 2,3,6-trisubstituted 2,3-dihydro-4-pyridones from methyl 3,5-dioxohexanoate, aryl aldehydes and ammonium acetate is described.     

A convenient synthesis of 2-substituted 4-amino-5-pyrimidinecarbonitriles

Synthesis of the novel 2-halogenated 4-amino-5-pyrimidinecarbonitriles 3a,b starting from ethoxy-methylenemalononitrile 1 and cyanamide is described. Nucleophilic substitution of the reactive halogen atom leads to the derivatives 5a-g, 6 and 7a-h.     

A convenient synthesis of psoralen derivatives: Psoralen, 4-methyl-psoralen and 4-phenyl-psoralen

A convenient synthesis of psoralen derivatives, viz., 7H-furo [3.2-g] [1] benzopyran-7-one (psoralen), 5-methyl-7H-furo [3.2-g] [1] benzopyran-7-one(4-methyl-psoralen) and 5-phenyl-7H-furo [3.2-g] [1] benzopyran-7-one-(4-phenyl-psoralen) by blocking the 8-position of the starting compounds with iodine, subsequentClaisen migration followed by cyclisation is described

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Ein Einfacher Syntheseweg zu Psoralen-Derivaten: Psoralen, 4-Methyl-psoralen und 4-Phenyl-Psoralen

Zusammenfassung Zur Synthese der Titelverbindungen wird die 8-Position des als Ausgangsmaterial dienenden 7-Hydroxy-benzopyranons mit Jod blockiert, dann erfolgt Allylierung und nach einerClaisen-Wanderung die Cyclisierung.

     

A short synthesis of C-glycosyl pyrazoles and pyrroles

The sodium salt of TOSMIC reacted with (E)-3,4,5,6,7-penta-O-acetyl-1,2-dideoxy-1-C-nitro-D-galacto- (1) and -D-manno-hept-1-enitol (2) to give 3-(D-galacto- (3) and 3-(D-manno-penta-O-acetylpentitol-1-yl)-4-nitropyrrole (4) , respectively. Compound 1 reacted with diaryl nitrile imines, affording 1,3-diaryl-4-(1,2,3,4,5-penta-O-acetyl-D-galacto-pentitol-1-yl)pyrazoles 5 and 6 .