Process for preparing 3,5:4,6- protected derivatives of L- or D- gulonic acid, their use in preparing 2- keto-L- or D- gulonic acid or their esters or L- or D- ascorbic acid, and certain novel 2-nitrato-gulonate intermediates

摘要

The invention relates to a process in which a 3,5:4,6-protected derivative of L- or D-glulonic acid is prepared by contacting L- or D-gulono-1,4-lactone with an aldehvde dialkyl acetal, or with an aldehyde and an alcohol, in the presence of an acid having a pKa of less than 3. This protected derivative may be oxidised and hydrolysed to 2-keto-L- or D-gulonic acid or ester thereof, which in turn may be hydrolysed to L- or D-ascorbic acid. L-ascorbic acid is of course Vitamin C. The invention also relates to the novel intermediates produced by the above processes.