A Novel Synthesis of Tetrahydropyrazolo[1,5-c]pyrimidine-2,7(1H,3H)-diones

作者：Mirnik Jona; Groselj Uros^*; Novak Ana; Dahmann Georg; Golobic Amalija; Kasunic Marta; Stanovnik Branko; Svete Jurij

来源：Synthesis, 2013, 45(24): 3404-3412.

DOI：10.1055/s-0033-1339977

• pyrazolo[1,5-c]pyrimidines
• ring-switching
• cyclization
• saturated heterocycles
• 3-pyrazolidinones

A novel simple five-step synthesis of 1,6-disubstituted tetrahydropyrazolo[1,5-c]pyrimidine-2,7(1H,3H)-diones has been developed. The synthetic protocol starts with ring switching%26apos; transformation of commercially available 5,6-dihydro-2H-pyran-2-one into the 5-(2-hydroxyethyl)pyrazolidin-3-one, followed by addition of the latter to isocyanates, Appel bromination, cyclization, and N(1)-alkylation with alkyl halides to give the title compounds. In comparison to a 12-step synthesis reported recently, the present method is clearly superior with respect to the number of synthetic steps and versatility of substituents at position 6.

• 出版日期2013-12-17