H. Groger et al., SYNTHESIS OF PROTECTED NONPROTEINURIC ALP HA-AMINO-ACIDS AND OLIGOPEPTIDES FROM 2H-1,3-OXAZINES AND 2H-1,3-BENZOXAZINES VIA UGI REACTION, Tetrahedron, 51(26), 1995, pp. 7173-7180
The preparation of six-membered N,O-heterocyclic 2H-1,3-oxazines 1 and
2H-1,3-benzoxazines 2 and the use of them in the synthesis of the cor
responding alpha-amino acids 3a-c, 4a-c and oligopeptides 3d,e, 4d-f a
re described These compounds are prepared based on the Ugi four-compon
ent-condensation reaction.