Titanocene complexes by N,O-ligands were rationally designed and tuned for selective three-component aza-Friedel–Crafts reactions of indoles, aldehydes, and unmodified aniline. The combination of Cp2TiCl2 and 8-hydroxyquinoline favored the synthesis of the mono aza-Friedel–Crafts adducts, whereas Cp2TiCl2 combined with anthranilic acid overwhelmingly formed bis-indoles. 1H NMR titration experiments, mass spectroscopy, X-ray crystal structure analyses, and control experiments showed that the reaction of Cp2TiCl2 with 8-hydroxyquinoline resulted in a half-sandwich complex [CpTiCl­(C9H6NO)2] (I), in which the Lewis acidity was enhanced via fine-tuning steric and electronic properties of the Ti (IV) center, facilitating mono aza-Friedel–Crafts reaction of indoles, aldehydes, and aniline; in contrast, when anthranilic acid reacted with the same Ti­(IV) precursor, a bis-ligand sandwich complex Cp2Ti­[(o-NH2)­PhCOO]2 (II) was obtained, in which both Lewis acidity of titanium and cooperation with amino groups promoted further transformation of indoles into bis-indole adducts.

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The chemistry practical competition is an advanced form of practical teaching. It can make up for the problems of traditional laboratory teaching items such as obsolete content, backward technical methods, inadequate training, and insufficient innovation. The multi-level, multi-channel, and all-round chemistry laboratory skills competition system provides a rich training platform on which more and more students can be trained. The organic integration of chemistry laboratory skills competition activities and traditional laboratory teaching can promote teaching and learning, enhance training of laboratory skills, improve the quality of practical teaching, better cultivate students' practical ability, craftsmanship and social responsibility. The implement of cooperative measures transforms selective education into quality education and innovative education. As a result, a new model of chemical practice teaching with our school's characteristics will be formed.

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