The 4H-pyranopyrazoles are an important class of heterocyclic compounds due to their pharmacological and biological properties. Compounds bearing the pyranopyrazole system have been found to have various biological activities, for instance antimicrobial, anti-cancer and anti-inflammatory properties, analgesic activity, activity as hypoglycemic, hypotensive, and vasodilatory agents, inhibitory activity toward human Chk1 kinase, molluscicidal activity and antifungal properties. In addition, such heterocycles bearing 4H-pyran units are important precursors in the synthesis of a large family of medicinally useful compounds. One-pot, multicomponent reactions (MCRs) are synthetically powerful, owing to their short reaction times, high efficiencies and unique selectivities. They can form several chemical bonds simultaneously and have emerged as an efficient tool in organic and medicinal chemistry. They are well suited for the synthesis of valuable heterocyclic compounds. A number of synthetic approaches have been made for the synthesis of 1,4-dihydropyranopyrazoles using CAPB, CTACl, MDOs, urea, amberlyst-A21, piperidine, 23 [Dsim]AlCl4, 24 isonicotinic acid, EDDF, triethylamine, 1-butyl-3-methylimidazolium tetrafluoroborate, Ba(OH)2, 29 L-proline, c-alumina, per-6-amino-b-cyclodextrin, molecular sieves, NaBr, b-CD, polystyrene supported p-toluenesulfonic acid, ZrO2-NPs, 37 NFS-PWA, DES, PPI and Fe-CaOx/glutamic acid. Despite considerable progress, the need for the greener synthesis of biologically active molecules has emerged. The use of natural catalysts in organic synthesis offers many advantages in sustainable chemistry because the catalysts are inexpensive, readily available, non-toxic and show high selectivity. In continuation of our interest in the development of synthetic methodologies for organic transformations, We now report on the use of snail shell, abundant in Morocco, as a natural catalyst. In the present work, we describe the synthesis of 1,4dihydropyrano[2,3-c]pyrazoles using snail shell as a biocatalyst (Scheme 1).

中文翻译：

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使用蜗牛壳作为可生物降解和可重复使用的催化剂高效合成 1,4-二氢吡喃并[2,3-c]吡唑

由于其药理和生物学特性，4H-吡喃并吡唑是一类重要的杂环化合物。已发现带有吡喃并吡唑系统的化合物具有多种生物活性，例如抗微生物、抗癌和抗炎特性、镇痛活性、作为降血糖、降压和血管舒张剂的活性，对人 Chk1 激酶的抑制活性，杀软体动物活性和抗真菌特性。此外，这种带有 4H-吡喃单元的杂环是合成一大类药用化合物的重要前体。由于反应时间短、效率高和独特的选择性，一锅多组分反应 (MCR) 具有强大的综合能力。它们可以同时形成多个化学键，并已成为有机和药物化学中的有效工具。它们非常适合合成有价值的杂环化合物。使用 CAPB、CTAC1、MDO、尿素、amberlyst-A21、哌啶、23 [Dsim]AlCl4、24 异烟酸、EDDF、三乙胺、1-丁基- 3-甲基咪唑鎓四氟硼酸盐、Ba(OH)2、29 L-脯氨酸、c-氧化铝、per-6-氨基-b-环糊精、分子筛、NaBr、b-CD、聚苯乙烯负载的对甲苯磺酸、ZrO2-NPs、 37 NFS-PWA、DES、PPI 和 Fe-CaOx/谷氨酸。尽管取得了相当大的进展，但对生物活性分子的绿色合成的需求已经出现。在有机合成中使用天然催化剂为可持续化学提供了许多优势，因为这些催化剂价格低廉、易于获得、无毒且具有高选择性。为了继续我们对开发有机转化合成方法的兴趣，我们现在报告使用摩洛哥丰富的蜗牛壳作为天然催化剂。在目前的工作中，我们描述了使用蜗牛壳作为生物催化剂合成 1,4-二氢吡喃并 [2,3-c] 吡唑（方案 1）。