A new strategy for the synthesis of pyridines from N-propargylic beta-enaminothiones

Kelgokmen, Yilmaz
Zora, Metin
A new method for the synthesis of 2,4,5-trisubstituted pyridines from N-propargylic beta-enaminothiones is reported. beta-Enaminothiones were prepared by thionation of the corresponding beta-enaminones with Lawesson's reagent. When treated with diisopropylamine in DMF at room temperature, N-propargylic beta-enaminothiones yielded 2,4,5-trisubstituted pyridines in moderate to high yields, along with small amounts of 2-methylene-2,3-dihydro-1,4-thiazepines. The reaction was found to be general for a broad range of N-propargylic beta-enaminothiones and tolerated the presence of aromatic, heteroaromatic and aliphatic groups with electron-withdrawing and electron-donating substituents. The method could be widened to the internal alkyne-tethered N-propargylic beta-enaminothiones. This operationally simple method may provide rapid access to a library of functionalized pyridines of pharmacological interest.


A new approach for the synthesis of spiro and gem-dimethyl-substituted 1,4-oxazepines from N-propargylic beta-enaminones
Karadeniz, Eda; Kelgökmen, Yılmaz; Zora, Metin (Wiley, 2020-11-01)
An efficient and general method for the synthesis of spiro-1,4-oxazepines and 3,3-dimethyl-1,4-oxazepines is reported. When treated with ZnI2 and AgSbF6 in refluxing DCE, cyclohexane-embedded N-propargylic beta-enaminones underwent 7-exo-dig cyclization to afford spiro-1,4-oxazepines, specifically 12-methylene-11-oxa-7-azaspiro[5.6]dodeca-7,9-dienes, in good to high yields. Accordingly, N-(1,1-dimethyl)propargylic beta-enaminones produced 3,3-dimethyl-1,4-oxazepines. Cyclization was found to be general for ...
A new and efficient chemoenzymatic route to both enantiomers of alpha '-acetoxy-alpha-methyl and gamma-hydroxy-alpha-methyl cyclic enones
Demir, Ayhan Sıtkı; Findik, H; Kose, E (Elsevier BV, 2004-03-08)
A chemoenzymatic synthesis of both enantiomers of the pharmacologically interesting alpha'-acetoxy-alpha-methyl and gamma-hydroxy-alpha-methyl cyclic enones starting from alpha-methyl-beta-methoxy cyclic enones is reported. Manganese(Ill) acetate-mediated acetoxylation followed by the enzyme-mediated hydrolysis of alpha'-acetoxy enone provides acetoxy enones 1a and 2a and hydroxy enones 1b and 2b with high enantiomeric excesses in good yields. The reduction of the acetoxy and hydroxy enones furnished both e...
Synthesis of ferrocenyl quinolines
Zora, Metin (Elsevier BV, 2008-06-01)
A convenient one-pot synthesis of ferrocenyl-substituted quinolines via a molecular iodine-catalyzed reaction of ferrocenylimines with enolizable aldehydes is reported. First, nucleophilic addition of the in situ generated enol to ferrocenylimine produces beta-anilinopropionaldehyde, which then undergoes intramolecular Friedel-Crafts reaction to give dihydroquinoline derivative. Finally, subsequent dehydration and aerobic oxidation affords ferrocenyl quinolines.
A new and efficient chemoenzymatic route to both enantiomers of alpha '-acetoxy and alpha '-hydroxy-alpha-methoxy cyclic enones
Demir, Ayhan Sıtkı; Caliskan, Z; Aydin, AE; Bicer, I (Elsevier BV, 2006-03-06)
A chemoenzymatic synthesis of both enantiomers of the pharmacologically interesting alpha'-acetoxy and alpha'-hydroxy-alpha-methoxy cyclic enones starting from alpha-hydroxy cyclic enones is described. Protection of 1,2-diketones, manganese(III) acetate-mediated acetoxylation followed by enzyme-mediated hydrolysis of alpha'-acetoxy enones gives acetoxy enones 3a-d and hydroxy enones 4a-d with high enantiomeric excesses (up to 99%) and good yields. The transesterification of rac-4b in the presence of DMAP af...
A novel one-pot synthesis of ferrocenyl-substituted 1,2,4-oxadiazoles
Zora, Metin; Kelgokmen, YILMAZ (Elsevier BV, 2014-06-01)
One-pot synthesis of 5-ferrocenyl-1,2,4-oxadiazoles via the reaction between 3-ferrocenylpropynal and amidoximes is described. 3-Ferrocenylpropynal reacts with a variety of amidoximes in the presence of KOH in refluxing dioxane to afford a broad range of 5-ferrocenyl-1,2,4-oxadiazole derivatives. The reaction first produces the corresponding conjugate addition product which, upon cyclization and rearrangement, yields the targeted 1,2,4-oxadiazole. The reaction appears to be general for a diversity of amidox...
Citation Formats
Y. Kelgokmen and M. Zora, “A new strategy for the synthesis of pyridines from N-propargylic beta-enaminothiones,” ORGANIC & BIOMOLECULAR CHEMISTRY, pp. 2529–2541, 2019, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/37437.