Screening of the catalytic performance of clusters as the catalysts for multicomponent coupling reaction of benzaldehyde, piperidine and phenylacetylene^a.

Entry	Catalyst	Yieldb
1	TiO2	n.d.
2	Au2Ag2/TiO2	81%
3	Au25/TiO2	62%
4	Au13/TiO2	45%
5c	Au2Ag2/TiO2	80%
6d	Au2Ag2/TiO2	79%

^aReaction conditions: 100 mg metal clusters/TiO₂ catalysts, 1.0 mmol benzaldehyde, 1.2 mmol piperidine, 1.3 mmol phenylacetylene, 5 mL water, 16 h, under a N₂ atmosphere; n.d. = not detected.

^bThe yield of propargylamine was determined by ¹H NMR.

^c2^nd reuse of the catalyst recovered from entry 2.

^d3^rd reuse of the catalyst recovered from entry 5.