Reaction of 1,3-disubstituted acetone derivatives with pseudohalides: A simple approach to spiro[4.4]nonane-type bis-oxazolidines and -imidazolidines(bicyclic carbamates, thiocarbamates, ureas, and thioureas)

Prochiral 1,3-dihydroxyacetone forms racemic oxazolidine-and oxazoline-type spiro[4.4]nonanes upon reactions with potassium (thio)cyanate and cyanamid e. In contrast, 1,3-diaminoacetone yields only the corresponding spiro-bisi midazolidinethione under similar conditions together with monocyclic by-pro ducts, but the spiro- bisimidazolidinone is accessible by reaction of 1,3-d ichloroacetone with urea. The resolution of the racemic spiro-bisoxazolidin ethione 2a was achieved by using brucine as the resolving agent.