We report efficient Pd-catalyzed cyclizations of oxime esters with 1,1-disubstituted alkenes as the basis of a general entry to α,α-disubstituted pyrrolidine derivatives. We also demonstrate that catalytic asymmetric variants of this chemistry are feasible by employing a suitable chiral ligand.

Lipase B from Candida antarctica (CALB) has been selected as the most suitable enzyme to catalyze the regioselective monoacetylation of 1,5-diol isoprostane intermediate, using vinyl acetate as an acyl transfer reagent in THF. We next applied this reaction on linear 2-substituted, 2,2'-disubstituted-1,5-pentanediols, and cyclic 2,3-disubstituted-1,5-pentanediols. To rationalize the regioselecti...

An efficient method for the synthesis of 3,5-disubstituted pyrazoles is described. The reactions of 1,3-dialkynes with hydrazine proceeded smoothly in dimethyl sulfoxide under mild reaction conditions to produce 3,5-disubstituted pyrazoles in satisfactory to excellent yields. A one-pot procedure of the transformation has been developed.

The coupling of an acyl chloride with an isocyanide affords 2,5-disubstituted oxazoles under mild basic conditions instead of 4,5-disubstituted derivatives when using Schöllkopf conditions (butyllithium); this reaction constitutes a remarkable example of a base-induced chemoselective process in isocyanide chemistry.

The reaction of N,N’-persubstituted selenoacrylamides with alkyl bromoacetates gives rise to the formation of alkyl derivatives of N,N-disubstituted 2-aminoselenophene-5-carboxylates which can be transformed by saponification into corresponding 5-carboxylic acids. These compounds decompose by heating under formation of hitherto unknown N,N-disubstituted 2-amino-5H-selenophenes their spectral an...

BACKGROUND Prior work from these laboratories has centred on the development of enaminones as versatile intermediates for the synthesis of alkaloids and other nitrogen-containing heterocycles. In this paper we describe the enantioselective synthesis of indolizidine and quinolizidine analogues of bicyclic amphibian alkaloids via pyrrolidinylidene- and piperidinylidene-containing enaminones. RE...

Abstract Hydrofunctionalization, the direct addition of an X–H (e.g., X=O, N) bond across alkene, is a desirable strategy to make heterocycles that are important structural components naturally occurring molecules. Described here design and discovery “donor–acceptor”-type platinum catalysts highly effective in both hydroalkoxylation hydroamination unactivated alkenes over broad range substrates...

A highly enantio- and diastereoselective sulfa-Michael addition of thioacetic acid to α,β-disubstituted nitroalkenes catalysed by a chiral squaramide organocatalyst has been described. This organocatalytic reaction at an extremely low catalyst loading (0.2 mol%) furnished synthetically useful β-nitro sulfides in excellent yields with good diastereoselectivities and high enantioselectivities (up...

Introduction: Oxidative stress and resulting lipid peroxidation are involved in numerous pathological conditions. For this reason, the role of antioxidants attracts attention radical-scavenging capacity many natural synthetic supplements drugs has been extensively evaluated. Material methods: In present study, seven N,N'-disubstituted benzimidazole-2-thiones with ester (1 - 4) hydrazide (5 7) s...