Gingras, Marc published the artcileSynthesis of carbohelicenes and derivatives by “carbenoid couplings”, Quality Control of 126613-06-7, the publication is Tetrahedron Letters (1999), 40(7), 1309-1312, database is CAplus.
Short synthetic sequences to helicenes have been achieved under thermal conditions, without using photochem. and high dilution Couplings of aromatic bis(bromomethyl) moieties, in the presence of an excess of LiHMDS, are key reactions in the final ring closures to helicenes. These optimized, quick and efficient reactions occur at 0°C within 10 min. and often provide [5]-helicene, [5]-helicene derivatives and [7]-helicene in ∼75% yield. Preliminary data questioned the formation of carbenoid anions and carbenes in the so called “carbenoid couplings”.
Tetrahedron Letters published new progress about 126613-06-7. 126613-06-7 belongs to esters-buliding-blocks, auxiliary class Chiral Diphenols, name is (R)-[1,1′-Binaphthalene]-2,2′-diyl bis(trifluoromethanesulfonate), and the molecular formula is C22H12F6O6S2, Quality Control of 126613-06-7.
Referemce:
https://en.wikipedia.org/wiki/Ester,
Ester – an overview | ScienceDirect Topics