1.2- cyclohexanediamine

Cyclohexanediamine is marketed by Milliken Chemical as an epoxy curative, Millamine 5260. It may be adducted with epichlorohydrin to generate solventiess low viscosity curatives for varnishes and surface coatings (76). Other cycloaHphatic diamines have long been modified as epoxy curatives to modify their reactivity profile (77). 

The 1,2-cyclohexanediamine-derived sulfonamide is not unique in its ability to afford enantiomerically enriched cyclopropanes. The efforts at improving the original protocol led not only to higher selectivity, but to a deeper understanding of the nature of the catalytic process. 

To optimize selectivity, a wide array of diamine backbones were surveyed (Fig. 3.21). However, it appears that 1,2-cyclohexanediamine is unique in its catalytic properties. Only the closely related dihydrophenanthrene ligand 124 could... 

Another point for structural diversification is the sulfonamide group. Imai had already shown that a wide variety of groups could be introduced at this position to optimize the reaction. Since a wide variety of sulfonyl chlorides are commercially available, a number of different types of groups could be examined (Scheme 3.34). Testing of a variety of aryl and alkyl groups on the 1,2-cyclohexanediamine backbone demonstrates that the simple methanesulfonamide 122 is clearly superior or equal to many other analogs in the cyclopropanation of cinnamyl alcohol (Table 3.11). Another concern which was directly addressed by this survey was the question of catalyst solubility. 

Cyclohexanediamine with diphenacyl sulhde, appearing to react as ben-zoyl(thiopyruvic) acid, gave a separable mixture of cis- and trani-3-phenyl-4a,5,6,7,8,8a-hexahydro-2(lF/)-quinoxalinethione (214) [HOCH2CH2OH-EtOH, 20°C, 10 days (or reflux, 4 h) 10% and 6%, respectively]." ... 

Scheme 4.10 Addition of ZnEt2 to acetophenone with 1,2-cyclohexanediamine-derived ligands.

Another idea developed by Yus et al. was to use other linkers with a low conformational freedom, such as 1,2-cyclohexanediamine derivatives. " ... 

In CC14 suspension, chlorine oxidation of [Ni(diamine)3]Cl2 affords unstable orange [Ni(diamine)3]Cl3 (diamine = en, 1,3-propanediamine, 1,2-cyclohexanediamine, 1,2-diamino-2-methylpropane, V-methylethanediamine) some of these species are stable for a few weeks in a... 

Enantioselective hydrogenation of prochiral ketones has rarely been studied in aqueous biphasic media. In addition to the chiral bisphosphonic acid derivatives of 1,2-cyclohexanediamine [130], the protonated 4,4 -, 5,5 -, and 6,6 -amino-methyl-substituted BINAP (diamBINAP 2HBr) ligands (Scheme 38.7) served as constituents of the Ru(II)-based catalysts in the biphasic hydrogenations of ethyl acetoacetate [131, 132]. These catalysts were recovered in the aqueous phase and used in at least four cycles, with only a marginal loss of activity and enantio-selectivity. 

C. (R,R)-N,N -Bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexanediamine. A 2-L, three-necked, round-bottomed flask equipped with a mechanical overhead stirrer, reflux condenser, and an addition funnel is charged with 29.7 g of (R,R)-1,2-diammoniumcyclohexane mono-(+)-tartrate salt (0.112 mol), 31.2 g of potassium carbonate (0.225 mol, 2 eq), and 150 mL of water. The mixture is stirred until dissolution is achieved, and 600 mL of ethanol is added. The cloudy mixture is heated to reflux with a heating mantle and a solution of 53.7 g (0.229 mol, 2.0 eq) of 3,5-di-tert-butylsalicylaldehyde in 250 mL of ethanol is then added in a slow stream over 30 min (Note 19). The addition funnel is rinsed with 50 mL of ethanol and the mixture is stirred at reflux for 2 hr before heating is discontinued. Water, 150 mL, is added and the stirred mixture is cooled to <5°C over 2 hr and maintained at that temperature for another hour. The yellow solid is collected by vacuum filtration and washed with 100 mL of ethanol. After the solid is air dried, it is dissolved in 500 mL of methylene chloride. The organic solution is washed with 2 x 300 mL of water, followed by 300 mL of saturated aqueous sodium chloride. The organic layer is dried over sodium sulfate, and filtered to remove the drying agent. The solvent is removed by rotary evaporation to yield the product as a yellow solid, mp 200-203°C (Notes 20 and 21). 

The corresponding reaction of 23 with dimethylamine and with cyclic secondary amines (piperidine and morpholine) is less facile and gives the thermodynamically more favored C-3 addition product (Equation 13) <1999RCB1150>. Using ethylenediamine, the cyclization product 29 is obtained in 80% yield (Scheme 12), although with 1,3-propane-diamine, 1,4-butanediamine, and 1,2-cyclohexanediamine the yields are reduced (70%, 25%, and 1%, respectively), consistent with the importance of entropy as a driving force for the second (intramolecular) amination. 

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