Bucherer–Bergs reaction

Nucleophilic addition of aminonitrile to CO2 leads to cyano-carbamic acid, which undergoes an intramolecular ring closing to 5-imino-oxazolidin-2-one.

Bucherer improved on Bergs’ method, finding that lower temperatures and pressures for the reaction were permissible.

First, the reaction of 2-Methyleneaziridine 1 with Grignard reagent, catalytic Cu(I), and R2-X causes the 2-Methyleneaziridine to ring open and form a ketimine 2.

This reaction has three points of chemical diversity as the structure of the aziridine starting compound, the organometallic reagent, and the electrophile can all be varied to synthesize a different hydantoin.

[7] One variation of the Bucherer–Bergs reaction is the treatment of carbonyl compound with carbon disulfide and ammonium cyanide in methanol solution to form 2,4-dithiohydantoins.

[9] In some cases, the carbonyl starting material can be sufficiently sterically biased so a single stereoisomer is observed.