SYNTHETIC APPROACHES TO BREVIANAMIDES A AND B I. PREPARATION OF 4-p-METHOXYBENZYL-5-(1'-CARBOMETHOXY-2'-METHYLIDENE)-1,2-L-PYROLIDINOPIPERAZINE-3,6-DIONE VIA AN IRELAND ESTER ENOLATE CLAISEN REARRANGEMENT.

Article abstract of DOI:10.1016/S0040-4039(00)86106-7

Using an ester enolate Claisen rearrangement to prepare 1-carbomethoxy-2-(1',1'-dimethylallyl)-2,3-dihydroindole-2-carboxylic acid followed by condensation with N-p-methoxybenzyl-glycyl-L-proline anhydride gave the title compound, a key intermediate in a synthetic approach to brevianamides A and B.