An efficient and green approach for the synthesis of 2,4-dihydropyrano[2,3-c]pyrazole-3-carboxylates using Bi2O3/ZrO2 as a reusable catalyst

作者：Bhaskaruni Sandeep V H S; Maddila Suresh; van Zyl Werner E; Jonnalagadda Sreekantha B^*

来源：RSC Advances, 2018, 8(29): 16336-16343.

DOI：10.1039/c8ra01994k

A novel material of bismuth loaded on zirconia (Bi2O3/ZrO2) is synthesized by simple wet-impregnation method and characterized by several techniques (P-XRD, TEM, SEM, BET, etc.). Bi2O3/ZrO2 proved to be a good catalyst for the four-component, one-pot reaction to produce a new series of 2,4-dihydropyrano [2,3-c] pyrazole-3-carboxylate derivatives with excellent yields (91 to 98%) under mild conditions at RT with short reaction times (approximate to 20 min). The structures of the target molecules were confirmed by H-1 NMR, C-13 NMR, N-15 NMR, HRMS and FT-IR. The catalyst is easily separable and can be reused for six cycles without ostensible loss of activity. This method is inexpensive, atom-efficient and no chromatographic separations are needed.

• 出版日期2018