The synthesis of 2-bromo[6]helicene was revised and improved up to 51% yield. Its reactivity was thoroughly investigated, and a library of 17 different carbon, boron, nitrogen, phosphorus, oxygen and sulfur substituted derivatives was prepared. The racemization barrier for 2-bromo[6]helicene was determined, and the usage of enantiomers in the synthesis of optically pure helicenes was rationalized. The three most energy-demanding reactions using enantiomerically pure 2-bromo[6]helicene were tested in order to confirm the predicted enantiomeric excess.

In this study, 9-(diphenylphosphanyl)[7]­helicene was prepared as a suitable ligand for the subsequent synthesis of palladium complexes. The corresponding PdL2Cl2 complex was then successfully obtained in both racemic and enantiopure forms. The PdL2Cl2 complex emerges exclusively in the trans arrangement showing dynamic interconversion between its homo- and heterochiral forms as evidenced by 31P NMR. The trans arrangement was ultimately confirmed by X-ray crystallography using single crystals of the homochiral complex. Additionally, the PdL2Cl2 complex was subjected to screening of its catalytic activity in a Suzuki-type reaction of aryl bromides with aryl boronic acids showing fair yields of the resulting biaryls. However, the final asymmetric reactions catalyzed by the optically pure PdL2Cl2 complex provided targeted binaphtyls only in negligible enantiomeric excess.

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 starting 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.The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acs.orglett.2c01723.Synthetic details, Experimental procedures, 1 H, 13 C and 31 P NMR spectra, characterization data for all new compounds, HPLC analysis, computational data, UV− vis, CD and crystallographic data (PDF) FAIR data, including the primary NMR FID files, for compounds 1

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