Pyrazolinone stereochemistry

Alkenes conjugated with are electron-deficient and hence do not react readily with organic peroxy acids. The observation that the stereochemistry of the pyrazolinone (109) is not retained in the epoxidadon product (110) is interesting (equation 38). The epoxide (110) is not fomaed directly fiom (109). Since the double brad in (109) is electron-deficient its peroxy acid epoxidadon to furnish (111) is a slow process. The isomerizadon the (Z)-pyrazolinfast process. MCPBA epoxidadon of the ( )-isomer derived from (109) Amishes (110). 

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