Diastereoselective conjugate addition reactions of 2 '-hydroxypropiophenone to 2 '-hydroxychalcones - Synthesis and structural characterization of the diastereomers of (+/-)-3-aryl-1,5-bis(2-hydroxyphenyl)2,4-dimethyl-1,5-pentanediones

The diastereoselective synthesis of 3-aryl-1,5-bis(2-hydroxyphenyl)-2,4-dim ethyl-1,5-pentanediones has been carried out by conjugate addition reaction s of 2'-hydroxypropiophenone to 2'-hydroxy-alpha-methylchalcone derivatives , or in single one-pot reactions of 2'-hydroxypropiophenone with appropriat e benzaldehyde derivatives. The structures and stereochemistry of the obtai ned diastereomers have been determined using various NMR techniques, and th e factors determining their formation are investigated and discussed.