Syntheses of [5]-helicene by McMurry or carbenoid couplings

Article abstract of DOI:10.1016/S0040-4039(98)00996-4

Short syntheses of [5]-helicene have been accomplished under thermal conditions, without using photochemistry and high dilution. Key reactions comprised a Mcmurry coupling of a dialdehyde or a carbenoid-type coupling of aromatic bis(bromomethyl) moieties. The last coupling provide a 72% yield of [5]-helicene on a gram-scale (15 min O°C).