Synthesis of Symmetrically and Unsymmetrically Substituted α-Diones from Organometallic Reagents and 1,4-Dialkylpiperazine-2,3-diones

Article abstract of DOI:10.1021/jo00096a049

The reaction of an equimolar mixture of N,N'-dialkylethylenediamines and diethyl oxalate in diethyl ether or 2-propanol leads to 1,4-dialkylpiperazine-2,3-diones.As cyclic and nearly planar tetraalkyl oxamides, these compounds are able to react with 2 equiv of organolithium or Grignard compounds to form, after hydrolysis, symmetrically substituted α-diones in excellent yields.The sequential addition of 1 equiv each ot two different organolithium compounds affords unsymmetrically substituted α-diones when the more soluble longer chain dialkyl derivatives of piperazine-2,3-dione are employed.The dialkylethylenediamines can conveniently be recovered and recycled to the 1,4-dialkylpiperazine -2,3-diones in good yields.