| abstract |
There is disclosed a dihalo-compound of formula (1):n nwherein X 1 and X 2 represent different halogen atoms, nR represents a hydrogen atom or a protective group for a hydroxyl group, andna process for producing vitamin A derivative via a sulfone derivative ofnformula (5):n nwherein Ar represents an optionally substituted aryl group, and R representsnthe same as defined above. |