Indole analogs of mycophenolic acid

Jones conditions), aqueous acid, and mild Lewis acids.The Boc group is usually removed by treatment with aqueous HCll or with anhydrous trifluoroacetic acid. In Lai s synthesis of indole analogs of mycophenolic acid, indole derivative 143 was converted to the N-Boc compound (144) using Boc anhydride. Elaboration of the side chain in three steps was followed by deprotection with HCl in dioxane, giving 145 in 72% yield. Trifluoroacetic acid in dichloromethane converted 145 to 146 in 60% yield. 

Another acylation procedure uses iminium salts rather than acyl halides. The Vilsmeier-Haack reaction is a well-known process illustrated by reaction of pyrrole with the POCI3 complex of N,N-dimethylacetamide (207, which can decompose to a chloroiminium salt). The acylation reaction gave 208, which was converted to 2-acetylpyrrole by hydrolysis with aqueous sodium acetate.A synthetic example is taken from Lai s synthesis of indole analogs of mycophenolic acid,l in which 209 reacted with POCI3 and DMF to give a 77% yield of the aldehyde 210. 

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