Syntheses of Diamino‐dideoxylyxose Derivatives using Acylnitroso Dienophiles

N‐Acylnitroso derivatives 6 which were prepared by in‐situ oxidation of the corresponding hydroxamic acids 5 reacted instantaneously and in high yields with dihydropyridine 4. The Diels‐Alder adducts 8 were formed regiospecifically with the acylnitroso dienophiles 6a–c, whereas the dienophiles 6d–f gave mixtures of both regioisomers 7 and 8. These and some other results [2] were best explained by the FMO theory. The Diels‐Alder adducts 7 and 8 gave the corresponding ‘anti’‐cis‐glycols when reacted with OsO4/N‐methylmorpholine N‐oxide. Hydrogenolysis of the N–O bond followed by peracetylation led to the expected aminolyxose derivatives 14 and 16. A similar sequence, using 4 and the hydroxamic‐acid derivative 18 of (+)‐D‐mandelic acid led, with a poor asymmetric induction, to a mixture of the expected optically active aminolyxose compounds 19A/19B.