Stereochemistry of the bucherer-bergs reaction and a modified strecker reaction on tetrahydro-2H-pyran-3-ones

The stereochemical aspects of the Bucherer-Bergs reaction and a modified Strecker reaction on tetrahydro-2H-pyran-3-one derivatives have been studied in details through the use of several nmr techniques. It was found that, in both reactions, the orientation of the substituents introduced on C-3 of the pyran ring, depends from the number and nature of the substituents on the neighbouring C-2 atom.