Polyfunctionalized cage compounds by pericyclic domino processes of 4,5-dicyanopyridazine with dienes: Applications and limits

The title compound 1 was found to behave as an attractive mashed bis-diene to give 3-oxatricyclo-[4.3.1.0(3,7)]dec-8-ene, 5-aza- and 5-silatricyclo[5. 3.1.0(3,8)]undec-9-ene, tricyclo[3.2.1.0(2,7)]oct-3-ene, and tricyclo[5.3.1 .0(3,8)]undec-9-ene derivatives through purely pericyclic, three-step homod omino processes with diverse bis-dienophiles; whereas the reaction with myr cene (21) was characterized by a complete sitoselectivity affording compoun d 25, treatment of 1 with (R)-(-)-beta-citronellene (26a) gave a 3:1 mixtur e of the homochiral diastereomers 30a and 31a. Some limits of this methodol ogy, mainly arising from competitive side reactions upon the key cyclohexa- 1,3-diene intermediates, are emphasized. The structures of the new compound s were established on the basis of spectral data.