The Huisgen 1,3-dipolar cycloaddition of azides and acetylenes catalyzed by Cu(I) salts, leading to 1,2,3-triazoles, is one of the most versatile "click reactions". We have developed a series of optimized protocols and new applications of this reaction starting from several substrates, comparing heterogeneous vs homogeneous catalysis, conventional heating vs microwave irradiation or simultaneous microwave/ultrasound irradiation. Both non-conventional techniques strongly promoted the cycloaddition (bromide → azide → triazole), that could be conveniently performed in a one-pot procedure. This was feasible even with such bulky molecules as functionalized β-cyclodextrins (β-CD), starting from 61-O-tosyl-β-CD or from heptakis[6-O-(tert-butyldimethylsilyl)]-21-O-propargyl-β-CD. "Greener" heterogeneous catalysis with charcoal-supported Cu(II) or Cu(I) (prepared under ultrasound) was advantageously employed.
Huisgen 1,3-二极环加成反应是由Cu(I)盐催化的叠氮化物和乙炔的反应,产生1,2,3-三唑,是最多才多艺的“点击反应”之一。我们开发了一系列优化的方案和这种反应的新应用,从多种底物出发,比较了非均相与均相催化,传统加热与微波辐射或同时微波/超声辐射。这两种非传统技术都强烈促进了环加成反应(溴化物→叠氮化物→三唑),可以方便地在一锅法中进行。即使是如功能化β-环糊精(β-CD)这样的庞大分子,也可以从61-O-对甲苯磺酰基-β-CD或从七甲基[6-O-(叔-丁基二甲基硅基)]-21-O-丙炔基-β-CD出发实现。利用炭负载的Cu(II)或Cu(I)(在超声下制备)进行的“更绿色”非均相催化被有利地应用。