ol202924s_si_001.pdf (8.77 MB)
Download file

Pyridines from Azabicyclo[3.2.0]hept-2-en-4-ones through a Proposed Azacyclopentadienone

Download (8.77 MB)
journal contribution
posted on 2012-01-06, 00:00 authored by Karl Hemming, Musharraf N. Khan, Vishnu V. R. Kondakal, Arnaud Pitard, M. Ilyas Qamar, Craig R. Rice
Pyridines have been formed by heating azabicyclo[3.2.0]hept-2-en-4-ones in toluene. The generation of a 3-azacyclopentadienone intermediate via a [2 + 2]-cycloreversion is proposed as the key step. A Diels–Alder reaction of a styrene, extrusion of carbon monoxide, and loss of hydrogen then gives the pyridine. The process parallels the well-known synthesis of benzenes from cyclopentadienones. The azabicyclo[3.2.0]hept-2-en-4-ones were synthesized from the reaction between readily available cyclopropenones and 1-azetines, in which the cyclopropenones behave as all-carbon 1,3-dipolar equivalents.