A thorough study of the synthesis of 2,4-diacylpyrroles by direct acylation of pyrrole and 2- and 3-acylpyrroles is reported. Among these, Friedel–Crafts acylation of 3-acylpyrroles is the most general and advantageous method because it utilises easily accessible starting materials. In addition it is always regiospecific and readily provides 2,4-diacylpyrroles containing identical or different acyl groups in very high yields (81–100%) under mild conditions. Alternative procedures concern the synthesis of precursors of 2,4-diacylpyrroles containing one or two acyl groups masked by a 1,3-benzodithiolyl or 1,3-benzoxathiolyl group and subsequent hydrolysis with HgO–35% aq. HBF4Me2SO. Overall yields are always good (52–60%). Indirect acylation constitutes a secure complement to direct acylation when it is necessary to operate in the presence of protected acyl groups.

General Metohds for Synthesizing 2,4-Dicaylpyrroles and their Precursors Containing One or Two Masked Groups

CADAMURO, Silvano;DEGANI, Jacopo;DUGHERA, Stefano;FOCHI, Rita;GATTI, Antonella;PISCOPO, Laura
1993-01-01

Abstract

A thorough study of the synthesis of 2,4-diacylpyrroles by direct acylation of pyrrole and 2- and 3-acylpyrroles is reported. Among these, Friedel–Crafts acylation of 3-acylpyrroles is the most general and advantageous method because it utilises easily accessible starting materials. In addition it is always regiospecific and readily provides 2,4-diacylpyrroles containing identical or different acyl groups in very high yields (81–100%) under mild conditions. Alternative procedures concern the synthesis of precursors of 2,4-diacylpyrroles containing one or two acyl groups masked by a 1,3-benzodithiolyl or 1,3-benzoxathiolyl group and subsequent hydrolysis with HgO–35% aq. HBF4Me2SO. Overall yields are always good (52–60%). Indirect acylation constitutes a secure complement to direct acylation when it is necessary to operate in the presence of protected acyl groups.
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2; 4-diacylpyrroles 2- and 3-acylpyrroles Friedel–Crafts acylation of 3-acylpyrroles
S. CADAMURO; IACOPO DEGANI; STEFANO DUGHERA; RITA FOCHI; ANTONELLA GATTI; LAURA PISCOPO
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2318/3278
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