Note
During studies towards the synthesis of microcolin analogues, an unexpected dehydration was observed when 1-benzyloxycarbonyl-4-hydroxy-5-methylpyrrolidin-2-one was treated with di-tert-butyl dicarbonate in the presence of 4-dimethylaminopyridine. This reaction was used for the stereospecific synthesis of several N-protected pyrrolin-2-ones. The elimination of β-hydroxyl groups in 4-hydroxy-pyrrolidinones with di-tert-butyl dicarbonate is described.