Boger pyridine synthesis

What is Boger pyridine synthesis?

The Boger pyridine synthesis, also known as the Boger reaction, is a chemical process that utilizes pyrrolidine as a catalyst to transform norborneone (bicyclo[2.2.1]heptanone-2) and 1,2,4-triazine into substituted pyridines. This synthesis involves both a hetero-Diels-Alder intermediate and a retro-Diels-Alder reaction.

Boger pyridine synthesis
Boger pyridine synthesis

Specifically, the reaction of triazine 1 with activated alkene 2 occurs in a hetero-Diels-Alder fashion, forming the unstable intermediate bicyclic species 3, which readily undergoes cycloreversion through the loss of nitrogen gas to yield the appropriately substituted pyridine derivative 4.

Boger pyridine synthesis is an approach based on cycloaddition chemistry highly effective for synthesizing pyridine rings in a single step. This method is not only efficient and promotes atom economy, but its convergency also enables the preparation of highly substituted systems where all five positions on the pyridine ring can be controlled in principle.

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