3779-29-1

Colourless Oil

Intermediate in the production of Carboplatin

The preparation of diethyl 1,1-cyclobutanedicarboxylate is as follows:The major product is tetraethy1 1,1,5,5-pentanetetra-carboxylate II with diethyl malonate. To eliminate this side reaction, II was independently prepared by the addition of hydrogen bromide to diethyl allylmalonate (I) and then cyclized to II by treatment with sodium ethylate. The over-all yield from I is about 50%.