Alkene ozonolysis in the presence of diazo functionality: accessing an intermediate for squalestatin synthesis

Studies on both the propensity for intramolecular cycloaddition between diazo and alkene functionality, and the tolerance of α-substituted α-diazoesters towards ozone in the presence of an alkene, led to chemoselective alkene ozonolysis of an ε-unsaturated-α-diazoester to give a key racemic diazoketone for the synthesis of 6,7-dideoxysqualestatin H5.