Asymmetric synthesis of multi-substituted triptycenes via enantioselective alkynylation of 1,5-dibromoanthracene-9,10-dione

Enantioselective alkynylation of 1,5-dibromoanthracene-9,10-dione by alkynyllithium reagents prepared from alkynes, n-BuLi, and sparteine gave chiral cis-diols possessing two alkyne moieties with moderate ee. Subsequent Ru-catalyzed [2+2+2] cycloaddition of the diol with alkynes afforded chiral 1,5-dibromotriptycenes.

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cis-1,5-Dibromo-9,10-bis(phenylethynyl)-9,10-dihydroanthracene-9,10-diolC30H18Br2O2Ee = 58% from HPLC[α]D26 = −128 (c 0.70, CHCl3)Source of chirality: (+)-sparteineAbsolute configuration: not determined

cis-1,5-Dibromo-9,10-dihydro-9,10-bis[2-(4-methoxyphenyl)ethynyl]anthracene-9,10-diolC32H22Br2O2Ee = 55% from HPLC[α]D26 = −112 (c 0.67, CHCl3)Source of chirality: (+)-sparteineAbsolute configuration: not determined

cis-1,5-Dibromo-9,10-bis(2-(4-chlorophenyl)ethynyl)-9,10-dihydroanthracene-9,10-diolC30H16Br2Cl2O2Ee = 60% from HPLC[α]D26 = −119 (c 0.37, CHCl3)Source of chirality: (+)-sparteineAbsolute configuration: not determined

2,3-Bis(hydroxymethyl)-5,13-bis(4-methoxyphenyl)-1,4-diphenyl-9,10-dihydro-9,10-[1,2]benzenoanthracene-9,10-diolC48H38O6[α]Hg43526 = +23.4 (c 0.49, CHCl3)Source of chirality: (+)-sparteineAbsolute configuration: not determined

cis-1,5-Dibromo-9,10-di(hex-1-ynyl)-9,10-dihydroanthracene-9,10-diolC30H16Br2Cl2O2Ee = 50% from HPLC[α]D26 = −87.2 (c 0.62, CHCl3)Source of chirality: (+)-sparteineAbsolute configuration: not determined

5,13-Dibromo-2-butyl-1,4-diphenyl-9,10-dihydro-9,10-[1,2]benzenoanthraceneC36H28Br2O2Ee = 58% from HPLC[α]Hg43526 = −212 (c 0.20, CHCl3)Source of chirality: (+)-sparteineAbsolute configuration: not determined

5,13-Dibromo-2-hexyl-1,4-diphenyl-9,10-dihydro-9,10-[1,2]benzenoanthraceneC38H32Br2O2Ee = 58% from HPLC[α]Hg43526 = −216 (c 0.21, CHCl3)Source of chirality: (+)-sparteineAbsolute configuration: not determined

5,13-Dibromo-2,3-bis(hydroxymethyl)-1,4-diphenyl-9,10-dihydro-9,10-[1,2]benzenoanthracene-9,10-diolC34H24Br2O4Ee = 58% from HPLC[α]Hg43526 = −17.0 (c 0.85, CHCl3)Source of chirality: (+)-sparteineAbsolute configuration: not determined