SYNTHESIS OF SUPERTRIPTYCENE AND 2 RELATED IPTYCENES

A 10-step 23-30% overall yield synthesis of supertriptycene (2) from vinyl chloride 5 is described. Anthracene 3 is the key intermediate, prepared from 5 in six steps and 41-53% yield (Scheme II). trans-1,2-Dichloroethene adds to 3 to give adduct 22 (94%), which is then converted to 2 in three steps and 70% yield (Scheme IV). A key step in the latter sequence is the remarkable cycloaddition of unactivated alkene 26 to hindered diene 4 in excellent yield. Supertriptycene (2), C104H62, shows only seven peaks in its H-1 NMR spectrum and 12 peaks in its C-13 NMR spectrum, consistent with its D3h symmetry. The hydrocarbon is stable to well over 500-degrees-C. Anthracene 3 was also converted to undecaiptycene 12 and to tridecaiptycene 16; the latter was also independently synthesized in two steps from alkene 26 and diene 28.