Stereochemie der Denitrogenierung von optisch aktivem 9,10‐Dihydro‐5,6‐diazalumibullvalen zu optisch aktivem 3,4‐Dihydrosemibullvalen

Stereochemical Course of the Denitrogenation of Optically Active 9,10‐Dihydro‐5,6‐diazalumibullvalene to Optically Active 3,4‐Dihydrosemibullvalene Thermal decomposition of optical active diazalumibullvalene derivative (+)‐ 6 gives optical active dihydrosemibullvalene (+)‐ 5 . The absolute configurations of optical active 6 and 5 were determined by correlation to tricyclooctanone 9 and 2‐cyclopentene‐1‐acetic acid ( 21 ), respectively. From these results it is concluded that thermal denitrogenation of 6 occurs by concerted six‐electron cycloreversion competing most likely to a multi‐step N 2 elimination via the symmetrical diradical intermediates 8 and 7 .