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Note | Regular issue | Vol 55, No. 9, 2001, pp.1789-1803
Published online, 1st January, 1970
DOI: 10.3987/COM-01-9218
Synthesis and Vasorelaxant Potency of Monagra. A Chiral 5-(2-Methyl-2,3-dihydro-7-benzofuryl)pyrazolopyrimidone Analog of Viagra®

Nader R. Al-bojuk, Mustafa M. El-Abadelah,* Salim S. Sabri, Alain Michel, Wolfgang Voelter, Cäcilia M.-Mössmer, and Yousef Al-Abed

*Chemistry Department , Faculty of Science, University of Jordan, Amman 11942, Jordan

Abstract

Synthesis and properties of a chiral 5-(2-methyl-2,3-dihydro-7-benzofuryl)pyrazolo[4,3-d]pyrimidin-7-one (3), an analog of Viagra“ (1) and Biagra (2), are described. The key material, (±)-3-methyl-2,3-dihydrobenzofuran-7-carboxylic acid (8a) was resolved into the (S)-8b (95% ee) and (R)-8c (99% ee) enantiomers using, respectively, (-)-cinchonidine and (+)-cinchonine. The absolute configuration of 8c was determined as R by X-Ray measurements. Preliminary in vitro experiments on rat isolated thoracic aorta show that the vasorelaxant potency of 3b,c is truly higher than that of 1 and 2.