86688-89-3Relevant academic research and scientific papers
General Methods for Synthesizing 2,4-Diacylpyrroles and their Precursors Containing One or Two Masked Acyl Groups
Cadamuro, Silvano,Degani, Iacopo,Dughera, Stefano,Fochi, Rita,Gatti, Antonella,Piscopo, Laura
, p. 273 - 284 (2007/10/02)
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 (81-100percent) 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-35percent aq.HBF4-Me2SO.Overall yields are always good (52-60percent).Indirect acylation constitutes a secure complement to direct acylation when it is necessary to operate in the presence of protected acyl groups.
Regioselective Synthesis of Acylpyrroles
Kakushima, Masatoshi,Hamel, Pierre,Frenette, Richard,Rokach, Joshua
, p. 3214 - 3219 (2007/10/02)
The regioselective synthesis of several pyrrole derivatives is described.AlCl3-catalyzed acylation reactions of 1-(phenylsulfonyl)pyrrole (1) give 3-acyl derivatives, whereas the corresponding BF3*OEt2-catalyzed reactions give 2-acyl derivatives predominantly.Mild alkaline hydrolysis gives the corresponding acyl-1H-pyrroles in excellent yields.AlCl3-catalyzed reactions of 1 with 1,1-dichloromethyl methyl ether and oxalyl chloride give 1-(phenylsulfonyl)-2-formylpyrrole (6) and 1-(phenylsulfonyl)-2-(chlorocarbonyl)pyrrole (7), respectively. 3-Pyrrolylacetic acid (10) was prepared by thallium(III) nitrate promoted rearrangement of 1-(phenylsulfonyl)-3-acetylpyrrole (2a).Trifluoroacetic anhydride catalyzed cyclization of 4-butyric acid (14) gives 1-(phenylsulfonyl)-7-oxo-4,5,6,7-tetrahydroindole (17).Attempts to cyclize 14 at the 4-position have been unsuccessful.
