Synthesis of 2-Phospha[7]helicene, a Helicene with a Terminal

A synthetic strategy toward phosphahelicenes containing a terminal phosphinine ring has been explored. The 4-phenyl-6-methyl-2-phospha[7]helicene was prepared from start-ing 2-bromobenzo[c]phenanthrene in 12% overall yield in 12 steps. The synthetic approach involves introduction of the phosphorus function prior to photocyclization forming the final helicene skeleton, followed by the formation of a phosphorus hexacycle. The structure of the first phosphahelicene with a terminal phosphinine ring was confirmed by X-ray crystallography.

Automated summary

A synthetic strategy for phosphahelicenes with a terminal phosphinine ring was explored. The 4-phenyl-6-methyl-2-phospha[7]helicene was synthesized in 12 steps from 2-bromobenzo[c]phenanthrene with an overall yield of 12%. The synthetic approach involved introducing the phosphorus function before photocyclization to form the helicene skeleton, followed by the formation of a phosphorus hexacycle. The structure of the first phosphahelicene with a terminal phosphinine ring was confirmed by X-ray crystallography.