A general [3 + 2 + 1] annulation strategy for the preparation of pyridine N-oxides.
[figure: see text] Stabilized ketone, aldehyde, and ester enolates react with vinamidinium hexafluorophosphate salts and hydroxylamine hydrochloride to give access to the corresponding pyridine N-oxides. The annulation reactions proceed in good to excellent yields with vinamidinium salts with a range of beta-substituents (R3 = halo, aryl, nitro, trifluoromethyl).
Davies
I W
IW
Department of Process Research, Merck & Co., Inc., P.O. Box 2000, Rahway, New Jersey 07065, USA. ian_davies1@merck.com
Marcoux
J F
JF
Reider
P J
PJ
D000447:Aldehydes; D000890:Anti-Infective Agents; D004952:Esters; D007202:Indicators and Reagents; D007659:Ketones; D015394:Molecular Structure; D010087:Oxides / Q000138:chemical synthesis* / Q000737:chemistry; D011725:Pyridines / Q000138:chemical synthesis* / Q000737:chemistry
D000447:Aldehydes; D000890:Anti-Infective Agents; D004952:Esters; D007202:Indicators and Reagents; D007659:Ketones; D010087:Oxides; D011725:Pyridines