Stereoselective Cycloaddition of Dibenzoxazepinium Ylides to Acetylenes and Fullerene C<sub>60</sub>. Conformational Behavior of 3-Aryldibenzo[<i>b</i>,<i>f</i>]pyrrolo[1,2-<i>d</i>][1,4]oxazepine Systems

Cycloaddition of dibenzoxazepinium ylides to acetylene carboxylates leads to <i>cis</i>-3<b>-</b>aryl-3,13b-dihydrodibenzo[<i>b</i>,<i>f</i>]pyrrolo[1,2-<i>d</i>][1,4]oxazepinecarboxylates, which smoothly dehydrogenate to the corresponding pyrrole derivatives. The <i>o</i>-bromophenyl-substituted pyrrole, in contrast to the pyrroline analogue, demonstrates atropoisomerism. Stereoselective cycloaddition of dibenzoxazepinium ylides to fullerene C<sub>60</sub> gives rise to fulleropyrrolidines with cis-configuration. Restricted Ph group rotation is found in the phenyl derivative. Only one of two possible atropoisomers is formed in the reaction of <i>o</i>-bromophenyl-substituted ylide with fullerene C<sub>60</sub>. Details of cycloaddition and conformational behavior of cycloadducts were studied by DFT computations.