BACKGROUND Trifluoromethylated alkene scaffolds are known as useful structural motifs in pharmaceuticals and agrochemicals as well as functional organic materials. But reported synthetic methods usually require multiple synthetic steps and/or exhibit limitation with respect to access to tri- and tetrasubstituted CF3-alkenes. Thus development of new methodologies for facile construction of Calke...

A formal [4 + 2] annulation occurs between 1,3-disubstituted cyclobutenols and internal alkynes in the presence of rhodium(I) catalysts to afford 1,2,3,5-tetrasubstituted benzenes. These benzannulation products are generated through dehydration of the initially formed cyclohexadienols.

A modular synthesis of tetrasubstituted furan carboxylates using a tandem cycloisomerization/oxidative carbonylation sequence of cyclopropenes has been successfully developed. The Tandem Metal Relay Catalysis (TMRC) pathway accounted for the high efficiency of this transformation.

The catalytic asymmetric phospha-Michael reaction of dialkyl phosphine oxides with β,β-disubstituted α,β-unsaturated carbonyl compounds was achieved. The products bearing tetrasubstituted carbon stereocenters were obtained in high yields with excellent enantioselectivities (up to >99% ee).

An efficient and general method for the synthesis of unsymmetrical tetrasubstituted ureas from carbamoylimidazole is described. The conversion is achieved by the concurrent quarternization of the imidazole nitrogen and activation of amines with AlMe(3).

2-Imidazolines and imidazoles have been accessed by an aza-Wittig sequence featuring novel N-acylation methodology for sulfonamides and optimized conditions for ring closure.

Nickel(0) catalysts were used to produce substituted imidazoles in good to high yields using benzonitrile, p-substituted benzonitriles and 4-cyanopyridine as starting materials.

BACKGROUND Derivatives of isoxazolopyridines exhibit diverse biological activity. One method of synthesizing isoxazolo[4,5-b]pyridines is Friedlander condensation. OBJECTIVES To establish the conditions necessary for conventional and microwave synthesis of new 3,5,6,7-tetrasubstituted isoxazolo[4,5-b]pyridines and their antiproliferative activity. MATERIAL AND METHODS The substrates in the ...

A synthesis of tetrasubstituted pyrazoles containing two, three or four pyridinyl substituents is described. Hence, the reaction of 1,3-dipyridinyl-1,3-propanediones with 2-hydrazinopyridine or phenylhydrazine, respectively, affords the corresponding 1,3,5-trisubstituted pyrazoles. Iodination at the 4-position of the pyrazole nucleus by treatment with I2/HIO3 gives the appropriate 4-iodopyrazol...

Tetrasubstituted (Z)-alkenes were readily prepared through the Horner-Wadsworth-Emmons reactions of methyl 2-[bis(2,2,2-trifluoroethyl)phosphono]propionate with aryl alkyl ketones by employing Sn(OSO(2)CF(3))(2) and N-ethylpiperidine.