A method of preparing an unsaturated compound, which comprises dehydrogenating a corresponding saturated compound in the presence of a catalytic system under conditions that result in the loss of one or more hydrogen (H2) molecules per molecule of the saturated compound, wherein the unsaturated compound is a compound of formula I (a) or I (b) and the saturated compound is a compound of formula II: ** (See formula) ** wherein R is H or = O; and Q is CH2, CH2CH2, CH (CH3) or C (CH3) 2.
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