Regioselective synthesis of pyrrolin-3-ones and 2,3,4,5-tetrahydro[1,3]-oxazines from N-vinylic amidines

Synthesis of Pyrrolin-4-ones by Pt-Catalyzed Cycloisomerization in PEG under Microwaves

“…A pyrrolinone scaffold similar to 2 is present in diverse pharmaceutically active compounds, and various families of nitrogen-containing heterocycles can be easily obtained by simple transformation of α-amino ynones 1 . However, straightforward procedures to pyrrolinones were poorly investigated in the past, and only rare examples are reported where ynones 1 were used as substrates in toxic mercury(II)- or gold(III)-catalyzed heterocyclization in volatile organic solvents under reflux. − In most of the cases, the yields were good, but the enantiomeric excess was not always satisfying and no recycling experiments of the catalyst were performed. In order to alleviate the potential loss of chiral integrity, we initiated a study with metals other than mercury or gold.…”

Chemistry of α-Oxoesters: A Powerful Tool for the Synthesis of Heterocycles

“…Reactions proceeded by nucleophilic addition of tautomeric form 942 to the keton moiety of oxomalonate to give intermediate 943, which underwent intramolecular cyclization to final 1,3-oxazines 944 (Scheme 307). 468 Scheme 305. Synthesis of Spiro [1,3] The reaction of 5-aryl-2,3-dihydro-2,3-furandiones with some N-cyano compounds was developed to synthesize 4H-1,3oxazin-4-ones 945,946.…”

“…When N -vinylic amidines, 2-azadienes, were subjected to diethyl oxomalonate in CHCl 3 at room temperature under an atmosphere of N 2 for 24 h, the HDA reaction (941) did not occurr, and, interestingly, diethyl 4-dialkylamino-2-ethoxycarbonylmethyl-2,5-dihydro-[1,3]­oxazine-6,6-dicarboxylates 944 were obtained in 37–42% yields. Reactions proceeded by nucleophilic addition of tautomeric form 942 to the keton moiety of oxomalonate to give intermediate 943 , which underwent intramolecular cyclization to final 1,3-oxazines 944 (Scheme ) …”