3-Aryl-substituted 3-pyrrolin-2-ones

Clayden and coworkers reported intramolecular Michael-addition— fragmentation leading to 3-vinyl- and 3-aryl-substituted 3-pyrrolin-2-ones (20040L609). For example, treatment of the carboxamide 178 (DEB = 1,1-diethylbutylcarbonyl) with LDA gives 3-pyrrolin-2-one 180 through a fragmentation of the initial Michael adduct 179 (Scheme 39). 

The De Kimpe group prepared 4-aryl-3-pyrrolin-2-ones starting with cyclobutanones (Scheme 47 2004SL1059). Treatment of cyclobutanone 207 with isopropylamine followed by sodium methoxide led to the amide 208 via a ring-opening reaction and substitution—ehmination. 

Quai and coworkers utilized a [4+1] cycloaddition with isocyanide to prepare highly substituted 3-pyrroHn-2-ones (Scheme 60 2004TL1413). Treatment of benzylidene-1,3-diketone 243 with tert-butyl isocyanide (244) gives 5-hydroxy-3-pyrrolin-2-ones 246 (Scheme 24). The authors propose an oxidative rearrangement mechanism for the conversion of initial adduct 245 to the observed product 246. Similar reactions have been reported by others in the synthesis of 3-aryl-4-carboethoxy-5-hydroxy-3-pyrrolin-2-ones (2007T8987) and 3,5-diaryl-5-hydroxy-3-pyrrolin-2-ones (2007TL8056). 

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