Azlactones reaction with Grignard reagents

In contrast to these ring-opening reactions, it was observed by Horner and Schwahn that 4-arylidene-(isopropylidene and cyclo-hexylidene)-oxazolones react with alkyl Grignard reagents by conjugate addition to give saturated azlactones 29a as the only products [Eq. (18)]. 

The outcome of Grignard reactions on 5(4H)-oxazolones likewise depends on the nature of the substituent at C(4). The saturated azlactone (210) is converted by the action of phenylmagnesium bromide into the tertiary acylamino alcohol shown in equation (48) on the other hand, saturated azlactones are obtained by the action of alkyl Grignard reagents on (arylmethylene)oxazolones (equation 49). This type of oxazolone reacts with arylmag-nesium halides at the carbonyl group in the presence of copper chloride, however, the addition is directed to the methylene carbon atom. 

---