intermediates heterocyclic Halide chemicals cyan chemicals boronic chemicals sulfon chemicals

Access to furanyl- and pyrrolyl-3-carboxamides from readily available 3-alkyne-1,2-diols and 1-amino-3-alkyn-2-ols using isocyanate as amido surrogate is demonstrated. The approach constitutes a successful unprecedented combination of heteropalladation and isocyanate insertion, a new avenue for novel amide bond constructions. The mechanism likely involves a 6-membered oxaaminopalladacycle as the key intermediate.
The stereoselective amination of various chiral benzylic ethers using chlorosulfonyl isocyanate is developed, and the application of this method to the total synthesis of a potent antidepressant, (+)-sertraline, from readily available 1-naphthol is also described.
Aromatic-bridged bis(hydrazines) were found to be the main products in the reaction of hydrazine polyanions with -dibromo-o-xylene. It was confirmed that the reaction is driven by a metal-halogen exchange process. A three-step reaction mechanism is suggested.
Formation and use of a nitrogen dianion for selective hydrazine alkylation is reported. The scope and limitations of a new method were demonstrated. The novel method provides fast and easy access to substituted hydrazines, which are widely used as drugs, pesticides, and precursors for a variety of compounds in organic synthesis.
Pyrido[4,3-d]pyrimidin-4(3H)-one (1) was prepared by reacting 2-trifluoromethyl-4-iodo-nicotinic acid (2) with amidine 9a catalyzed by Pd2(dba)3 and Xantphos, followed by cyclization effected with HBTU and subsequent demethylation using PhBCl2. The amidine arylation method was found applicable for the syntheses of quinazolin-4(3H)-ones. Thus, reaction of 2-bromo or 2-iodo benzoate esters with amdidines afforded substituted quinazolin-4(3H)-ones in 44-89%
a convenient synthetic methodology for the conversion of meta-dinitro heterocyclic rings to iminoquinones with vinylogous amidine functionality. These structures are found in nature, particularly in marine organisms, and may be important for the pigments and biological activity observed with such marine secondary metabolites. Using benzimidazole and indole ring systems we show the versatility of these vinylogous amidines for organic synthesis, including the following: transamination substitution reactions with virtually any primary amine, regional control of the substitution with substituents between the vinylogous amidine, and hydrolytic properties that can be controlled or optimized based on the properties of the chosen ring system. Taken together, this versatile chemistry and functionalization of organic molecules may be useful in the preparation of a variety of chemical products such as drug pharmacophores or assembling macromolecular structures.
We have developed an efficient method for the synthesis of benzimidazoles via cascade reactions of o-haloacetoanilide derivatives with amidine hydrochlorides. The protocol uses 10 mol % CuBr as the catalyst, Cs2CO3 as the base, and DMSO as the solvent, and no ligand is required. The procedure proceeds via the sequential coupling of o-haloacetoanilide derivatives with amidines, hydrolysis of the intermediates (amides), and intramolecular cyclization with the loss of NH3 to give 2-substituted 1H-benzimidazoles.
A new synthetic approach to 4-substituted imidazo[4,5-c]pyrazoles is proposed on the basis of the N′-(4-halopyrazol-5-yl)amidine cyclization under the conditions of copper-catalyzed cross-coupling reactions. Using 5-aminopyrazoles and copper catalysts as starting materials, the method is inexpensive and convenient and allows a wide range of substituents at all positions of the imidazo[4,5-c]pyrazole nucleus.
The three-component reaction of ketones, arylacetylenes, and guanidine catalyzed by the KOBut/DMSO system leads to 2-aminopyrimidines in up to 80% yield. Depending on structure of the starting ketones, the aromatization of intermediate dihydropyrimidines occurs either with loss of hydrogen molecules or methylbenzenes. The latter process takes place in the ketones, in which one of the substituents is not a methyl group. The reaction conditions are tolerable for dialkyl-, aryl(hetaryl) alkyl-, and cycloalkyl ketones.
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