EventsThe 14th International Electronic Conference on Synthetic Organic Chemistry
Event submissions
Published
with-doi10.3390/ecsoc-14-00411
This submission belongs to the session e. Computational Chemistry of the event The 14th International Electronic Conference on Synthetic Organic Chemistry
Published date
20 Oct, 2010
Citation
Ponnadurai Ramasami, John A Joule, Luis R Domingo, Sabina Jhaumeer-Laulloo, Hassan H Abdallah, Lydia Rhyman, Cycloaddition of Methyl Acrylate with Substituted Pyridinium-3-olates and Pyrazinium-3-olates: 1,3-Dipolar Cycloaddition versus Diels-Alder, in Proceedings of The 14th International Electronic Conference on Synthetic Organic Chemistry, 1 November–30 November 2010, MDPI: Basel, Switzerland, doi: 10.3390/ecsoc-14-00411
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Cycloaddition of Methyl Acrylate with Substituted Pyridinium-3-olates and Pyrazinium-3-olates: 1,3-Dipolar Cycloaddition versus Diels-Alder

Ponnadurai Ramasami 1
John A Joule 2
Luis R Domingo 3
Sabina Jhaumeer-Laulloo 1
Hassan H Abdallah 4
Lydia Rhyman 1
1. Department of Chemistry, University of Mauritius, Réduit, Mauritius
2. The School of Chemistry, The University of Manchester, Manchester M13 9PL, UK
3. Departamento de Química Orgánica, Universidad de Valencia, Dr. Moliner 50, 46100 Burjassot, Valencia, Spain
4. School of Chemical Sciences, Universiti Sains Malaysia, 11800 Penang, Malaysia
Abstract
The 1,3-dipolar cycloaddition (1,3-DC) and Diels-Alder (DA) reactions of substituted pyridinium-3-olates and pyrazinium-3-olates with methyl acrylate are studied using DFT method at the B3LYP/6-31G(d) level of theory. The molecular mechanism of the possible stereo- and regiochemical pathways is characterized both in the condensed and solvent phases. It is found that 1,3-DC is the favourable pathway for the reaction of pyridinium-3-olates with methyl acrylate and the thermodynamically more stable 6-substituted 8-azabicyclo[3.2.1]oct-3-en-2-ones are formed preferentially. This research is further extended to substituted pyrazinium-3-olates. Reactions of unsubstituted pyrazinium-3-olate and 1-methyl pyrazinium-3-olate with both ethene and methyl acrylate show a preference for the DA cycloaddition reaction. However, the addition of methyl acrylate to substituted pyrazinium-3-olates results in competitive mechanistic pathways and the preferred cycloaddition pathway is dependent on the location of the methyl group on the pyrazinium ring. The presence of a methyl substituent on C5 of the pyrazinium-3-olate favours the 1,3-DC over the DA reaction as the 2,6 positions are not sterically crowded. However, when methyl groups are present at the C2 and C6 positions, cycloaddition occurs via a Diels-Alder route which is free from encumbrance and hence bond formation at the C5 position is more enhanced.
Keywords
pyridinium-3-olate
pyrazinium-3-olate
methyl acrylate
1,3-dipolar cycloaddition
Diels-Alder
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