Ytterbium triflide

Scheme 6 Preparation oftriflidic acid and ytterbium(IIl) and scandium(III) triflide...

Ytterbium(III) tris(trifluoromethanesulfonyl)methide (ytterbium(III) triflide) was applied in a catalytic amount to catalyse FC processes. Only 1 mol% of ytterbium (III) triflide at 80 C allowed acylation of thiophene and 3-methylthiophene with acid anhydrides [35]. Acylation of thiophene led exclusively to 2-substitution 3-methylthiophene gave a mixture of 2-acylated (8) and 5-acylated (9) products (Scheme 15) [35]. 

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