Propargyl azadienes

In another route employing alkynes, it was found that heating propargyl azadienes 7 in toluene at 25-60 °C produces pyrrolic imines 8 which hydrolyze upon work-up to afford 3-acylpyrroles 9 <96JOC2185>. This exo-dig cyclization occurs with complete chemoselectivity wherein the more substituted nitrogen is involved in the cyclization. 

On the other hand, intramolecular carbon—nitrogen bond formation leading to N-substituted-3-acylpyrroles 5 smoothly occurs in 79-96% yield by heating a solution of azadiene 2 having a propargyl appendage at the enamine carbon atom (R3 = CH2—-C C—R5) in toluene or ethanol/... 

The highly reactive 2-azadiene with an allene and heterocumulene structure 126, prepared by gas-phase thermolysis of propargyl thiocyanate, has been found by the Banert group to be an efficient precursor for thiazole derivatives by nucleophilic-induced heteroannulation through carbon and... 

The dimethylhydrazine derivative of diethyl 1-formylmethylphosphonate, on reaction with 0-propargyl-2-hydroxybenzaldehyde, gives an azadiene that, on heating in mesitylene at 138-162°C for several hours, participates directly in an intramolecular [4 -i- 2] cycloaddition (Scheme 5.82). ... 

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