1,1′-Binaphthyl-2,2′-Disulfonic Acid

[122361-59-5 InChI = 1S/C20H14O6S2/c21-27(22,23)17-11-9-13-5-1-3-7-15(13)19(17)20-16-8-4-2-6-14(16)10-12-18(20)28(24,25)26/h1-12H,(H,21,22,23)(H,24,25,26) InChIKey = ZSWODTYSMOCDKE-UHFFFAOYSA-N 852127-05-0 InChI = 1S/C20H14O6S2/c21-27(22,23)17-11-9-13-5-1-3-7-15(13)19(17)20-16-8-4-2-6-14(16)10-12-18(20)28(24,25)26/h1-12H,(H,21,22,23)(H,24,25,26) InChIKey = ZSWODTYSMOCDKE-UHFFFAOYSA-N 1092934-18-3] C20H14O6S2 (MW 414.4516) InChI = 1S/C20H14O6S2/c21-27(22,23)17-11-9-13-5-1-3-7-15(13)19(17)20-16-8-4-2-6-14(16)10-12-18(20)28(24,25)26/h1-12H,(H,21,22,23)(H,24,25,26) InChIKey = ZSWODTYSMOCDKE-UHFFFAOYSA-N (organocatalyst and ligand for metal complexes) Alternate Names: BINSA; 1,1′-binaphthalene-2,2′-disulfonic acid. Physical Data: mp 156–160 °C; [α]D23 = +61.4 (c 2.2, MeOH). Solubility: sol THF, DMF, CH3CN, CH2Cl2, CHCl3, MeOH, EtOH, H2O; less soluble in Et2O, EtOAc, toluene. Handling, Storage, and Precautions: moisture sensitive. Keep tightly closed under an inert gas atmosphere; store in a cool dark place. Preparative Methods: the potassium salt of racemic 1,1′-binaphthyl-2,2′-disulfonic acid (BINSA) was obtained by reacting potassium 1-iodonaphthalene-2-sulfonate with copper powder in an Ullmann coupling reaction.1 Similarly, the sodium salt of racemic BINSA was obtained from diphenyl 1,1′-binaphthalene-2,2′-disulfonate, which was prepared from phenyl 1-iodonaphthalene-2-sulfonate with copper powder in an Ullmann coupling reaction, by treatment with sodium/1-butanol under reflux conditions.2 Ishihara and coworkers. reported the practical asymmetric synthesis of optically pure (R)-BINSA from commercially available (R)-BINOL ((R)-1,1′-bi(2-naphthol)) in four steps (eq 1).3, 4 O-Thiocarbamoylation of (R)-BINOL, followed by thermolysis in Newman–Kwart rearrangement to the S-thiocarbamoyl compound by a microwave technique at milder temperature (200 °C) relative to traditional thermal conditions (270–400 °C),5-7 reduction to the dithiol by LiAlH4, oxidation by 10 atm of O2/KOH in HMPA, and protonation by ion exchange provided (R)-BINSA on a >10g scale without loss of optical purity. (1)