Dihalo-compound and process for producing vitamin A derivative

摘要

There is disclosed a dihalo-compound of formula (1): wherein X1 and X2 represent different halogen atoms, R represents a hydrogen atom or a protective group for a hydroxyl group, and a process for producing vitamin A derivative via a sulfone derivative of formula (5): wherein Ar represents an optionally substituted aryl group, and R represents the same as defined above.