Condensation of 3-quinuclidinone (I) with tert-butyl acetate using LDA in THF at low temperature gave hydroxy ester (II). Acid cleavage of the tert-butyl ester of (II), followed by esterification with MeOH and H2SO4 produced the methyl ester (III), which was transformed to hydrazide (IV) upon treatment with hydrazine in refluxing MeOH. Nitrosation of (IV) with NaNO2 and HCl, followed by Curtius rearrangement of the intermediate acyl azide furnished the target spiro oxazolidinone (V). The required (S)-enantiomer was then isolated by resolution with dibenzoyl-D-tartaric acid.
In an alternative procedure, reaction of quinuclidinone (I) with (R)-2-hydroxy-1,2,2-triphenylethyl acetate (VI) gave adduct (VII) as a single enantiomer. Subsequent ester hydrolysis of (VII) provided the chiral carboxylic acid (VIII). Finally, rearrangement of (VIII) in the presence of diphenyl phosphorylazide yielded the title compound.