Patent ID: 7511150

Claim:
A method of preparing N-(3,5-dichloropyrid-4-yl)-4-difluoromethoxy-8-methanesulfonamide-dibenzo[b,d]furan-1-carboxamide comprising the steps of: (a) reacting 4-difluoromethoxy-3-hydroxybenzaldehyde with 2-bromo-1-fluoro-4-nitrobenzene in a first solvent in the presence of an potassium fluoride to produce 4-difluoromethoxy-3-(4-nitro-2-bromophenoxy)benzaldehyde; (b) cyclizing 4-difluoromethoxy-3-(4-nitro-2-bromophenoxy)benzaldehyde in a second solvent in the presence of a catalyst to produce 4-difluoromethoxy-8-nitro-1-formyl dibenzofuran; (c) oxidizing 4-difluoromethoxy-8-nitro-1-formyl dibenzofuran in a third solvent in the presence of an oxidizing agent to produce 4-difluoromethoxy-8-nitrobenzo[b,d]furan-1-carboxylic acid; (d) reacting 4-difluoromethoxy-8-nitrobenzo[b,d]furan-1-carboxylic acid with 4-amino-3,5-dichloropyridine in a fourth solvent in the presence of an inorganic acid halide and a first base, to produce N-(3,5-dichloropyrid-4-yl)-4-difluoromethoxy-8-nitro-dibenzo[b,d]furan-1-carboxamide; (e) reducing N-(3,5-dichloropyrid-4-yl)-4-difluoromethoxy-8-nitro-dibenzo[b,d]furan-1-carboxamide in the presence of a reducing agent to produce N-(3,5-dichloropyrid-4-yl)-4-difluoromethoxy-8-aminodibenzo[b,d]furan-1-carboxamide; and (f) reacting N-(3,5-dichloropyrid-4-yl)-4-difluoromethoxy-8-aminodibenzo[b,d]furan-1-carboxamide with methanesulfonyl chloride in a fifth solvent in the presence of and a second base to produce N-(3,5-dichloropyrid-4-yl)-4-difluoromethoxy-8-(methanesulfonamide) dibenzo[b,d]furan-1-carboxamide.