(1R)-(-)-2-Azabicyclo[2.2.1]hept-5-en-3-one (Abacavir - In House Impurity) is an Abacavir (A105000) intermediate (1). It is also an intermediate in the synthesis of carbocyclic sugar amines, carbanucleosides, and carbocyclic dinucleotide analogues (2).