208646-48-4Relevant articles and documents
Process research and large-scale synthesis of a novel 5,6-dihydro-(9H)-pyrazolo[3,4-c]-1,2,4-triazolo[4,3-a]pyridine PDE-IV inhibitor
Urban, Frank J.,Anderson, Bruce G.,Orrill, Susan L.,Daniels, Peter J.
, p. 575 - 580 (2001)
An efficient synthesis of the PDE IV inhibitor, 9H-cyclopentyl-7-ethyl-3-(thiophen-2-yl)-pyrazolo[3,4-c]-1,2,4-triazolo-5,6- dihydro-[4,3-a]pyridine 1 is described. Starting from commercially available γ-caprolactone, the synthesis was carried out in 10 steps. Key transformations were the selective O-methylation of diketone, 3-hydroxy-1-(4-methoxybenzyl)-4-propionyl-5,6-dihydro-1H-pyridin-2-one, with dimethyl sulfate and cesium carbonate in dimethylformamide, a one-pot pyrazole formation with subsequent acidic deprotection to provide lactam, 1-cyclopentyl-3-ethyl-1,4,5,6-tetrahydropyrazolo[3,4-c]pyridin-7-one, and finally the utilization of imidate, 1-cyclopentyl-7-ethoxy-3-ethyl-4,5-dihydro-1H-pyrazolo[3,4-c]pyridine for the introduction of the triazole moiety. This process avoided the use of harsh reaction conditions, undesirable reagents and overcame the environmental concerns in the original synthesis.
