Study of the reaction between conjugated azoalkenes and α-unsubstituted- or α-substituted-β-dicarboxylate derivatives: an improved preparation of unknown polyfunctionalized 1-amino-1H-pyrrol-2(3H)-ones
Double 1,4-addition of malonate to 1,2-diaza-1,3-butadienes: a useful route to previously unknown symmetric and unsymmetric 1,6-dioxo-2,7-diazaspiro[4.4]nona-3,8-dienes