A New Approach to Neuraminic Acid Analogues via 1,2-Oxazines

A new stereoselective and potentially very flexible (C(5) + C(3) + C(1)) approach to neuraminic acid derivatives and analogues has been established using enantiopure nitrones and alkoxyallenes as C(3) and C(1) building blocks. Substituent OR(2) in position 4 of neuraminic acid analogues is defined by the alkoxyallene employed for the synthesis of the intermediate 1,2-oxazine. Side chain R(1) can be varied by using different precursor nitrones and introduction of different protection groups R(3) at the amino function is also possible.