Abstract The Michael reaction of ethyl cinnamates with deoxybenzoin gave ethyl 3, 4, 5- triaryl-5-oxopentanoates which were hydrolysed to the corresponding acids. The latter could be cyclized to the respective 3, 4-dihydro-2H-pyran-2-ones which underwent ring opening with several nucleophiles to the corresponding acid derivatives. However, their reaction with ammonium acetate led to the formation of 3, 4-dihydro-2-pyridones. The 3, 4-dihydro-2- ...