Asymmetric synthesis of pentono- and 6-deoxyhexono-δ-lactams via hetero-Diels-Alder reactions with nitroso dienophile

Asymmetric Diels-Alder reaction of the pentadienoic and hexadienoic acids 2a,b with the chiral chloronitroso derivative 3 gave the primary adducts 4a,b with good-to-excellent enantioselectivity. Subsequent cis- or Irans-dihydroxylation and hydrogenolytic cleavage of the N-O bond led to the 5-amino-5-deoxy-pentono-delta-lactams 13a, 14, 15a, and 16 in the D-ribose, L-arabinose, D-xylose, and L-lyxose series, respectively, and to the 5-amino-5,6-dideoxyhexono-delta-lactams 13b and 15b in the D-allose and D-glucose series, respectively.