Kilogram Synthesis of a LFA-1/ICAM Inhibitor

The process development and the kilogram-scale synthesis of BMS-587101 (1) are described. The synthesis features a [3 + 2] azomethine ylide cycloaddition to efficiently build the spirocyclic core in a diastereoselective fashion followed by a classical resolution which affords the desired enantiomer in >98% enantiomeric excess. The target was prepared in four steps in an overall yield of 22%.