(1S,1′S,2R,2′R,4R,4′R)-N,N′-(1R,2R)-1,2-cyclohexanediyl bis[2-hydroxy-2,7,7-trimethylcyclo[2.2.1]heptane-1-methanesulfonamide

Abstract

[264906-55-0] [264906-56-1] C26H46N2O6S2 (MW 546.78) InChI = 1S/C26H46N2O6S2/c1-23(2)17-9-11-25(23,21(29)13-17)15-35(31,32)27-19-7-5-6-8-20(19)28-36(33,34)16-26-12-10-18(14-22(26)30)24(26,3)4/h17-22,27-30H,5-16H2,1-4H3/t17-,18-,19-,20-,21-,22-,25-,26-/m1/s1 InChIKey = KVVHJCZXSZVOLS-BASDDVJQSA-N InChI = 1/C26H46N2O6S2/c1-23(2)17-9-11-25(23,21(29)13-17)15-35(31,32)27-19-7-5-6-8-20(19)28-36(33,34)16-26-12-10-18(14-22(26)30)24(26,3)4/h17-22,27-30H,5-16H2,1-4H3/t17-,18-,19-,20-,21-,22-,25-,26-/m1/s1 InChIKey = KVVHJCZXSZVOLS-BASDDVJQBC (reagent used as a ligand on titanium to generate a chiral Lewis acid for promotion of the asymmetric addition of alkyl, vinyl, dienyl, and aryl groups to ketones) Physical Data: mp 181–182 °C. Solubility: soluble dichloromethane, THF, toluene (slightly). Preparation: both enantiomers of the ligand are prepared in two steps from commercially available materials (eq 1). In the first step, the diamine and sulfonyl chloride react cleanly in the presence of triethylamine to afford the diketone in excellent yield. The crude diketone may be used directly in the NaBH4 reduction, which provides the desired ligand 1 as a mixture of diastereomers (3.5:1).1 The diastereomers are separable by column chromatography. The mixture of diastereomers has been used in some cases without detrimental effects on the enantioselectivity. (1) Purification: column chromatography on silica with ethyl acetate and hexanes. Handling, Storage, and Precautions: air-stable, crystalline solid. This ligand is used in combination with organozinc reagents that are pyrophoric and must be handled with care under nitrogen. Titanium tetraisopropoxide is used and should be distilled if needed. The ligand has also been used in tandem asymmetric addition/diastereoselective epoxidation reactions with oxygen or tert-butyl hydroperoxide (TBHP), which are oxidants. When these oxidants are employed in combination with dialkylzinc reagents, appropriate precautions must be taken.