Other Types of -Lactam Rearrangements

It can be prepared by treatment of 3-amino-2//-azirines (e.g. 3-(dimethyl-amino)-2,2-dimethyl-2//-azirine) with an amino acid or peptide and, finally, with a (u-hydroxyacid. The formation of the oxazolone, VI/121, is observed when VI/120 is treated with acid. The ring enlargement step, the conversion of VI/121 to VI/122, is observed under the same conditions. The transformation of (-)-(R,R)2- 2-[2-(2-hydroxy-2-phenylacetamido)-2-methylpropionato]-2-phenylacetamido -N,N,2-trimethylpropionamide (VI/123) to (-)-(R,R)-3,3,9,9-tetramethyl-6,12-diphenyl-l,7-dioxa-4,10-diazacyclododecane-2,5,8,ll-tetrone (VI/126) in dry toluene/hydrochloric acid at 100° was observed in a 88 % yield. Compounds VI/124 and VI/125 are discussed to be intermediates. In an analogous reaction sequence cyclopeptides can be synthesized [93]. 

10) Experiments for the reverse reaction VI/114— VI/113have not been described, ref. [88]. 

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