Compounds containing 2-pyrone, were studied for their selectivity, however nitrogen containing atom at a position to the substituent compound influence the selectivity. The compound containing a nitrogen atom at the meta-position to the cyclopentenone substituent shows no selectivity at all. Selectivity towards the β-position was observed for the pyrone containing 2-thiophene. However nitrogen containing in both ring system favoured the 2-pyridine at the β-position exclusively, suggesting that there may be an interaction of 2-pyridine with the cobalt complex. Further evidence is provided by 2-thiophene, where the 2-pyridine controls the regiochemical outcome, even though the α-isomer was observed. The 2-thiophene was observed controlling the regioselectivity over 4-pyridine. This suggested that the position of the nitrogen atom in pyridyl-containing system (with respect to the 2-pyrone) dramatically affects the regiochemical outcome of the PKR. Remarkably, 2-pyridine shows unique behaviour by having a significant effect on the selectivity of both the pi-electron deficient 2-pyrone and pi-electron rich 2-thiophene. PKR Compounds synthesis undergoes a light-induced C3-regioselective Pi- electrocyclisation/oxidative aromatisation reaction. This was conducted in natural light and gave cyclised compounds in 4 hrs. With more controlled irradiation (focussed LED at 400 nm) led to full conversion in 3 mins (monitored by UV-Vis and NMR).

Cobalt mediated regioselective Pauson-Khand reaction a possible Co-N participation and photo-induced oxidative 6Pi-electrocyclization/aromatization reactions

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.