Dimethyl oxaquadricyclane-2,3-dicarboxylate (1) with cyclooctyne (CO) gave, via carbonyl ylide (3a), a mixture of the exo and endo 1:1 adducts (2a, 2b) along with the novel 1:2 adduct (2c), whereas the carbocyclic analogs underwent [sigma 2s + sigma 2s + pi 2s]cycloaddition. The first examples of inverse electron demand homo-Diels-Alder reactions of oxa-, aza- and carbo-norbornadienes with CO were also described.
TIAN, GUAN RONG;MORI, AKIRA;KATO, NOBUO;TAKESHITA, HITOSHI, BULL. CHEM. SOC. JAP., 62,(1989) N, C. 506-513