4-ISOPROPYL-2-OXAZOEIN-5-ONE ANION AS MASKED UMPOLED SYNTHON FOR BOTHFORMYL AND HYDROXYCARBONYL ANIONS - GENERATION, REACTIVITY AND SYNTHETIC APPLICATIONS

The anion of the title compound, simply generated ill the presence of catalytic amount of triethylamine, reacts with both common electrophil ic olefins and aldehydes to give moderate to good yield of Michael or aldol adducts respectively. Mild acid treatment of these adducts at am bient temperature serves to demask the aldehyde function, allowing one to consider the anion of 1 as a nucleophilic acylating equivalent of formaldehyde. On the other hand, the same anion of 1 may act as a mask ed umpoled synthon for a hydroxycarbonyl anion since its aldol adducts with aldehydes underwent concomitant isomerization and ring cleavage under mild basic conditions producing dipeptides which could be hydrol yzed to give the corresponding carboxylic acids. Synthetic application s of this chemistry in the area of sugar, aminosugar and non-proteinog enic aminoacid derivatives are discussed.