2000 cycloaddition reactions

cycloaddition reactionsO 0070

01 - 054Hetero-Diels–Alder Reactions of Homochiral 1,2-Diaza-1,3-butadieneswith Diethyl Azodicarboxylate under Microwave Irradiation. The-oretical Rationale of the Stereochemical Outcome. — Diels–Alderreaction of chiral 1,2-diaza-1,3-butadienes derived from acyclic carbohydrates,e.g. (I), (II), and (III), with DEAD is greatly accelerated by microwaveirradiation and its stereoselectivity is markedly dependent on the relativestereochemistry at C-1’,2’, i.e. threo configuration at C-1’,2’, e.g. (I), givestetrazines with high facial selectivity whereas erythro configuration, e.g. (II)and (III), affords products in lower diastereomeric ratio. — (AVALOS,MARTIN; BABIANO, REYES; CINTAS, PEDRO; CLEMENTE, FERNANDOR.; JIMENEZ, JOSE L.; PALACIOS, JUAN C.; SANCHEZ, JUAN B.; J.Org. Chem. 64 (1999) 17, 6297-6305; Dep. Quim. Org., Fac. Cienc., Univ.Extremadura, E-06071 Badajoz, Spain; EN)

1