Toward Soluble 5,10-Diheterotruxenes: Synthesis and Reactivity of 5,10-Dioxatruxenes, 5,10-Dithiatruxenes, and 5,10-Diazatruxenes

The following work
presents three general approaches allowing,
for the first time, the synthesis of 5,10-diheterotruxene derivatives
containing two identical heteroatoms, namely, oxygen OOC, nitrogen NNC, or sulfur SSC. Two of described
pathways involve the photocyclization of the corresponding triene 2 as a key step leading to a heptacyclic aromatic system.
The third approach is based on the acidic condensation between ninhydrin 14 and benzo­[b]­heteroole 15.
Typical functionalizations of the 5,10-diheterotruxene core have also
been presented. In addition, the article discusses the advantages
and limitations of the three suggested paths for receiving specific
5,10-diheterotruxene derivatives because the universal method suitable
for obtaining molecules with any type of heteroatoms is not known
so far.