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Pisani et al., 53Part-IIImpact of Microwave…have developed a two-step protocol for the synthesis of 5-aroyl-3,4-dihydropyrimidin-2-ones libraries (30 compounds) of type 60, combining a trimethylsilylchloride-mediated Biginelli multicomponent approach with the transition metalcatalyzedLiebeskind-Srogl ketone synthesis. Both reaction steps can be efficiently carried out withcontrolled microwave irradiation.SEtOR 1R 3 -B(OH) 2H Pd(OAc) 2 PPh 3 , CuTCN solventMWI, 130 o C, 1hN OR 2R 3OR 1NR 260NHOR 1 = Ph, 3-BrPh, 2-CF 3 Ph etc.R 2 =H, CH 3 , C 2 H 5R 3 = Ph, 3-ClPh,4-CH 3 Ph, 3-OCH 3 Ph etc.A diverse set of 17 acidic carbonyl synthons, 25 aldehydes and 8 urea/thioureas was usedin the preparation of a dihydropyrimidine library 61. Out of the full set of 3400 possibleDHPM derivatives, a representative subset of 48 analogues was prepared using automatedaddition of building blocks and subsequent sequential microwave irradiation of eachprocess vial. For most building block combinations 10 min of microwave flash heating at120°C using AcOH/EtOH (3:1) and 10 mol % ytterbium trifluoromethanesulfonate[Yb(OTf) 3 ] as solvent/catalyst system proved to be successful, leading to an averageisolated yield of 52% of DHPMs with >90% purity. 54R 1R 1ER 2OO+HNR 3HNH 2ZAcOh/EtOHYb(OTf) 3MWI, 120 o C,10 min R 2 NER 361NHZR 1 =Ph, 2-NO 2 Ph, 4-NO 2 Ph, 3-OHPh,4-CH 3 Ph etcR 2 = CH 3 , C 2 H 5 , Ph etcR 3 = CH 3 , C 2 H 5 , CH 2 Ph, Ph etc.E= COOC 2 H 5 , COOCH 3 , COCH 3 , CONH 2 , etcYeh et al., 55 have successfully combined the advantages of microwave technology withliquid phase combinatorial chemistry to facilitate thioxotetrahydropyrimidinone 62300