AZO BRIDGES FROM AZINES .14. RIGID POLYCYCLES WITH N=N AND C=C FUNCTIONALITIES

Bifunctional 9, 3, 17, and trifunctional 20 dienophiles have been subj ected to Diels-Alder reactions with 4H-pyrazoles 8 or 14 with inverse electron demand to form monoadducts 13, 15, 18, and 21 and bisadducts 16, 19, and 26. Acid-catalyzed reactions at 20 degrees C occur accordi ng to 14 + 3 --> 15 + 16 and 14 + 17 --> 18 + 19. By contrast, the sol ution of barrelene (20) and 8 has to be subjected to 10 kbar and 130 d egrees C to give monoadduct 21 and bisadduct 26. In daylight 21 underg oes [2 + 2] cycloaddition to 27. The norbornene derivative 10 reacts w ith cyclopentadiene to form 13 which is obtained in higher yield by re action of 10 with hexachlorocyclopentadiene and subsequent reductive d ehalogenation of adduct 12. X-ray analyses of 11 and 13 reveal only sm all differences in the structural parameters.