Chiral Diamine Derivatives In Asymmetric Synthesis

Part oneHydrolytic Kinetic Resolution of Racemic Terminal Epoxides in the Presence of Non C2- Symmetric Chiral Co(III)(SaIen) as Catalysts.Reduction of L-valine with LAH gave valinol I-1, which was iV-protected with Z-Cl to form the N-benzyloxycarbonylvalinol I-2, which, was then converted to the corresponding azide I-3 by treating with mesyl chloride followed by sodium azide. I-3 was hydrogenated to give enantiopure (S)-3-methyl-l,2-butanediamine I-4. (R)-l,2-propanediamine was obtained in >99% enantiomeric purity by resolution of racemic diamine with d-tartaric acid. 3-tert-butyl-2-hydroxy-5-methyl-benzaldehyde I-7 was prepared from p-cresol by a two-step synthesis.Condensation of (S)-3-methyl-l,2-butanediamine I-4 /and (R)-l,2-propanediamine with 3-tert-butyl-2-hydroxy-5-methylbenzaldehyde I-7 gave the non-C2-symmetric chiral I-8a and I-8b, respectively. Refluxing I-8a /and I-8b in toluene with cobalt(II) acetate gave the Co(II)(Salen)complexes I-9a /and I-9b, respectively. These, while stirred with acetic acid open to air , were converted to the Co(III)(Salen)complexes I-10a /and I-10b, respectively.In the presence of 10a /and I-10b (0.2-1 mol%), the enantioselective hydrolysis of racemic terminal epoxides proceeds smoothly to give optically active diols and epoxides in excellent yields with the ees ranged from 4% to 30.5%.Part TwoAsymmetric Henry Reaction Catalyzed by chiral Cyclic GuanidinesN,N'-Dimethyl-(1R,2R)-diphenylethanediamine, on heating with urea, was converted to the l,3-dimethyl-(4R,5R)-diphenylimidazolidin-2-one, which was treated with excess of oxalic chloride followed by tert-butylamine to afford the chiral guanidine II-6a in high yield. Similarly was prepared the chiral cyclic guanidine II-6b. Chiral II-6c and II-13 were prepared from N,N'-dimethyl-(1R,2R) and N,N'-diisopropyl-(1R,2R)-diphenyl ethane-diamine in 95% and 90% yield, respectively, by reaction with cyanogen bromide.These chiral monocyclic guanidines were showen to be effective catalysts for asymmetric Henry reaction of nitromethane with benzaldehyde or isobutanal. In the reaction of isobutanal, up to 34% ee was observed.The attempt to prepare cyclic dipeptide baring a chiral guanidino-group was unsuscessful.Part Three Chiral Catalysts Derived from Diamine for Asymmetric Addition ofDiethylzinic to AldehydesSeven new polyfunctional chiral Hgands were readily prepared from chiral N,N'-dimethyl (or diisopropyl)-l,2-diphenyletheneamine or a-phenylethylamine with aldehydes; heating of benzylamine and (S)-styrene oxide gave chiral catalyst HI-IS. These eight chiral ligands were evaluated as catalysts for the enantioselective addition of diethylzinc to aromatic aldehyde. Catalyst III-1 was found to show the best asymmetric induction and catalyzed the reaction of m-chlorobenzaldehyde with diethylzinc to provide sec-alcohol in 95% yield, and the ee value up to 57%.