Resolved Epichlorohydrin

Scheme 126 shows the enantioselective cyclization of 1,3-dichloro-2-propanol to form partially resolved epichlorohydrin, which is achieved by combining small amounts of a chiral Schiff-base Co(II) complex and potassium carbonate (305). The same chiral Co(II) catalyst allows enantiomer-selective carbonation of propylene bromohydrin to afford propylene carbonate in fair chemical and optical yields (306). 

Isolation of Resolved Epichlorohydrin 2.4.2.2.1 Reaction Medium Stabilization... 

To validate IR imaging for screening reactions, the activity and enantioselectivity of metal catalysts (S,S)-4a-c for the hydrolysis of epichlorohydrin was tested. Time-resolved changes in temperature indicated that the (S,S)-4c catalyst as the most active and an S-configured epoxide (lc) is preferred for hydrolysis (Figure 3.45). 

The hydrolysis of epoxides is a well-known reaction which can be exploited for various synthetically useful outcomes. Chiral nonracemic epoxides can be prepared from their racemates through the salen-mediated hydrolytic kinetic resolution (HKR). Racemic epichlorohydrin 53 was resolved in the presence of catalyst 52 and a slight excess of water under solvent-free conditions. The catalyst counterion exerts a significant effect on the course of the reaction, presumably due to competitive addition onto the epoxide, an effect which is evident in apparent reaction rates, but not enantioselectivities. Less nucleophilic counterions, such as tosylate, lead to more rapid resolution and lower catalyst loading requirements <04JA1360>. 

Using a simple affinity system which required coupling of a-L-fucopyranose to macroporous agarose by epichlorohydrin treatment of the agarose in the presence of a-L-fucopyranose under alkaline conditions has been used to resolve a partially purified preparation of monkey brain a-L-fucosidase at pH 5.0 into two major fractions one bound and one retarded.The enzyme that was bound to the affinity column and specifically eluted by 2 mM a-L-fucose at pH 5.0 appeared to be homogeneous by polyacrylamide gel electrophoresis and was constituted mainly by the tetrameric form of the enzyme. The enzyme fraction retarded by the affinity column was found to contain mainly the monomeric form of the enzyme. Additional evidence for the different molecular forms of enzyme in the bound and retarded fractions came from pH-activity profiles and heat inactivation studies. The L-fucose-affinity matrix appeared to bind the tetrameric form of the enzyme specifically and, further, a-L-fucopyranose helped to retain the molecular integrity of the tetrameric enzyme. 

Epichlorohydrin-cross-linked cyclohexa- and cyclohepta-amylose gels have been used for the chromatographic resolution of racemic mandelic acid and its derivatives. Modified cyclohepta-amylose bound the L-(- -)-isomers preferentially, and resolved D,L-methyl mandelate to give the D-(—)-isomer of 100% optical purity in the first fraction. Cross-linked cyclohexa-amylose bound D-(—)-isomers more strongly than L-(-t-)-isomers, resolving D,L-methyl mandelate to a smaller extent than cross-linked cyclohepta-amylose. Binding was studied quantitatively by the equilibrium method. 

Urea-formaldehyde resin (UF) is a hydrophilic condensation polymer. The UF monosized non-porous microspheres were prepared with (-I-) L-2-amino-5-ureidopentanoic acid as the chiral ligand. The micro-spheres exhibited exceptional mechanical strength, chemical stability in the pH range 1-13, and low tendency toward swelling in solvents they were used for the CLEC separation of amino acids. Later, the porous UF microspheres were also prepared and L-proline was grafted via epichlorohydrin onto the polymer (l-proline content 0.28 mmol/g). Eighteen D,L-amino acids were resolved on the sorbent with aqueous ammonia... 

Epoxide- and Diol-Building Blocks (ChiRex). The latest technology for producing chiral epoxides and 1,2-diols is Jacobsen s hydroljdic kinetic resolution, technically developed by ChiRex for resolving propene and styrene oxide as well as epichlorohydrin on a multi-lOO-kg scale Qh,63). The technology was licensed to Daiso Co. for epichlorohydrin resolution on a multitons per year scale (64). 

Similar to silica, surface-modified cellulose (84,98,1(X),105,119) e.g. ECTEOLA (a reaction product of epichlorohydrin, triethanolamine and alkali cellulose), carboxymethyl cellulose, amino-benzyl cellulose and diethyl-(2-hydroxypropyl) aminoethyl cellulose have been used as stationary phases for the separation of several inorganic ions. Fixion 50X8 (a polymer based strong acidic cation exchange resin) is used to resolve various inorganic ions by circular TLC (127). 

ECTEOLA is named for the epichlorohydrin and triethanolamine groups which are combined with cellulose. DEAE-cellulose and ECTEOLA-cellulose layers have about the same ability to resolve nucleic acid derivatives. ECTEOLA is especially useful for nucleic acids, nucleotides and nucleosides as an anion exchanger. Its strength also lies in its rapid separation of pyrimidines from purines. 

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