Additions 10-camphorsulfonyl chloride

In 2000, these workers described disulfonamide ligands derived from camphor, which could be easily prepared from chiral camphorsulfonyl chloride, and further successfully used in the enantioselective addition of ZnEt2 to... 

After finding the right combination for the diamine linkers, Yus et al. tried to determine whether it was compulsory to use two isoborneol-10-sulfonamide moieties. In this context, these authors have prepared the ligand depicted in Scheme 4.24 by reaction of the best amine linker, trani-cyclohexane-1,2-diamine, with camphorsulfonyl chloride and then with methanesulfonyl chloride, followed by reduction with AlH(i-Bu)2 and then hydrolysis.When this new ligand was involved in the enantioselective addition of ZnEt2 to acetophenone, the expected tertiary alcohol was obtained in excellent yield and enantioselectivity of 96% ee, as shown in Scheme 4.24. According to this result, the authors concluded that the second isoborneol unit seemed not to be necessary to obtain a high enantioselectivity. 

Camphorsulfonyl chloride is rather rapidly hydrolyzed by warm water. The procedure here provides for complete hydrolysis of phosphorus oxychloride and excess phosphorus pentachloride without local heating and loss of product due to hydrolysis. For best results, the whole hydrolysis operation should be carried out quickly and steadily. It is well to have additional quantities of crushed ice on hand because the mixture may become quite hot if all of the ice added initially melts. 

Poor (<4% de) to modest (56% de) amounts of diastereofacial selection is observed in the cycloaddition of nitrile oxides to optically active acrylates. The plan in each case, of course, was to use a chiral auxiliary which would preferentially shield one of the two ir-faces of the dipolarophile. Of the auxiliaries used, the sulfonamide esters derived from (+)-camphorsulfonyl chloride worked best, the menthyl esters derived from (-)-menthol the poorest (<4% de). As illustrated in Table 19, changes in both temperature and solvent had either no or little affect on the product ratios. Unlike Diels-Alder reactions, the addition of Lewis acids, specifically Et2AlCl, EtAlCh and TiCL, resulted in significant decreases in both the rate of cycloaddition and isolated yield, without an appreciable change in diastereomer ratio. ... 

Since conjugate (Michael) addition and Diels-Alder reactions use a,p-unsat united carbonyl compounds, asymmetric versions of these reactions could use the auxiliaries that we have seen in aldol reactions in the form of 118 and 119. Diels-Alder reactions work very well with these unsaturated amides and also with amides 121 derived from Oppolzer s chiral sultam14 120, prepared simply from camphorsulfonyl chloride. 

Synthesis of Chiral Auxiliaries. Their availability and crystalline nature has made camphor derivatives the precursors of choice for the design and synthesis of chiral auxiliaries. 10-Camphorsulfonyl chloride is the starting material for the synthesis of chiral auxiliaries (9)-(12) (eq 2). Sulfonamides (9) and (10) have been used as chiral auxiliaries in a number of reactions, e.g. the Lewis acid-catalyzed Diels-Alder reaction, the [3 + 2] cycloaddition of a nitrile oxide to an acrylate, and the stereoselective conjugate addition reaction of organocopper reagents to ci ,)3-unsaturated esters. ... 

S. (-)-(Camphorsulfonyl)imine. A 1 -L, round-bottomed flask is equipped with a two-inch egg-shaped magnetic stirring bar, a Dean-Stark water separator, and a double-walled condenser containing a mineral oil bubbler connected to an inert gas source. Into the flask are placed 5 g of Amberylst 15 ion exchange resin (Note 4) and 41.5 g of the crude (+)-(1 S)-camphorsulfonamide in 500 mL of toluene. The reaction mixture is heated at reflux for 4 hr. After the reaction flask is cooled, but while it is still warm (40-50°C), 200 mL of methylene chloride is slowly added to dissolve any (camphorsulfonyl)imine that crystallizes. The solution is filtered through a 150-mL sintered glass funnel of coarse porosity and the reaction flask and filter funnel are washed with an additional 75 mL of methylene chloride. 

Oxidation is generally complete after addition of the oxone solution. The oxidation is monitored by TLC as follows remove approximately 0.5 mL of the toluene solution from the nonstirring solution, spot a 250-micron TLC silica gel plate, elute with methylene chloride and develop with 10% molybdophosphoric acid in ethanol and heating (camphorsulfonyl)imine R = 0.28 and (camphorylsulfonyl)oxaziridine R = 0.62. If (camphorsulfonyl)imine is detected, stirring is continued at room temperature until the reaction is complete (See Note 8). 

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