N-propargylation reaction of substituted 4H-pyrano[2,3-d]pyrimidine derivatives under conventional, ultrasound- and microwave-assisted conditions

Synthesis and inhibitory activity against MurA and MurZ enzymes of 4H-pyrano[2,3-d]pyrimidine–1H-1,2,3-triazole hybrid compounds having piperidine and morpholine rings

“…33 Reaction of these ethyl esters with acetic anhydride in the presence of trifluoroacetic acid (TFA) as catalyst under reflux at 100 °C for 15 min led to the production of 4 H -pyrano[2,3- d ]pyrimidines 7a–g and 8a–g , respectively (Scheme 2). 34 These compounds were formed with yields of 69–78% (Table S3 in the ESI†). The propargyl group was attached to the molecular frame of 4 H -pyrano[2,3- d ]pyrimidines 7a–g and 8a–g by its reaction with propargyl bromide in the presence of anhydrous K 2 CO 3 as a base in dried acetonitrile.…”

“…The reaction was performed at 50 °C under ultrasonic irradiation conditions to afford the corresponding N -propargyl derivatives 9a–g and 10a–g with yields of 85–89% (Table 1, Scheme 2). 34 The target molecules, 1 H -1,2,3-triazoles 12a–g and 13a–g , were synthesized from N -propargyl derivatives 9a–g and 10a–g of 4 H -pyrano[2,3- d ]pyrimidines by their click chemistry with 2,3,4,6-tetra- O -acetyl-β- d -glucopyranosyl azide 11 (Scheme 3). CuI@montmorillonite K10 was used as a catalyst in the presence of N , N -diisopropylethylamine (DIPEA) as an additive in the solvent mixture of t -butanol and water.…”