1,2,4-Triazines and Calcium Carbide in the Catalyst-Free Synthesis of 2,3,6-Trisubstituted Pyridines and Their D-, C-, and Doubly D - C -Labeled Analogues.

A novel synthetic approach to 2,3,6-trisubstituted pyridines, their 4,5-dideuterated derivatives, 4,5- C - and doubly-labeled D - C -pyridines has been developed using catalyst-free [4+2] cycloaddition of 1,2,4-triazines and in situ generated acetylene or labeled acetylene. Calcium carbide and water or deuterium oxide were used for the in situ generation of acetylene and dideuteroacetylene. Calcium carbide- C in the mixture with water or deuterium oxide was applied as C -acetylene and D - C -acetylene source.

Acetylene in Organic Synthesis: Recent Progress and New Uses.

Recent progress in the leading synthetic applications of acetylene is discussed from the prospect of rapid development and novel opportunities. A diversity of reactions involving the acetylene molecule to carry out vinylation processes, cross-coupling reactions, synthesis of substituted alkynes, preparation of heterocycles and the construction of a number of functionalized molecules with different levels of molecular complexity were recently studied. Of particular importance is the utilization of acetylene in the synthesis of pharmaceutical substances and drugs.

[3 + 2]-Cycloaddition of in Situ Generated Nitrile Imines and Acetylene for Assembling of 1,3-Disubstituted Pyrazoles with Quantitative Deuterium Labeling.

A novel synthetic methodology for the preparation of 1,3-disubstituted pyrazoles from in situ generated nitrile imines and acetylene is reported. The reactions are performed in a simple two-chamber reactor. One part of the reactor is loaded with hydrazonoyl chloride precursors of active nitrile imine species and a base.