(±)-4-Amino-4,5-dideoxyribose, (±)-4-amino-4-deoxyerythrose,and (±)-dihydroxyproline derivatives from N-dienyl-γ-lactams

Hetero-Diels-Alder cycloaddition of acylnitroso dienophile 4 with the N-(butadienyl)pyrrolidinone derivatives 2a , b led with complete regioselectivity to the oxazine adducts 5a , b (Scheme 1). Sequential osmylation, protection of the ensuing glycol, and reduction of the N? O bond gave the expected hemiaminals 11a , b which were characterized by their crystalline sulfite adducts 12a , b (Schemes 1 and 2). Deprotection and saponification of the latter led to aminodeoxyerythrose and to aminodeoxyribose derivatives as an equilibrium of pyrrolidinose equivalents, i.e., hemiaminals 14a , b , imines 14′a , b , and dimers 14″a , b , respectively (Scheme 3). Hydrocyanic acid addition to 11a , b led ultimately to the proline derivatives 16a , b (Scheme 2). Compound 11b proved to be an inhibitor of syncytium formation in AIDS-infected cells.