Enzymatic Resolution Of γ-Lactones And Dynamic Kinetic Resolution Of α-Branched Aldehydes By Using Asymmetric Transfer Hydrogenation Reaction

1. Preparation of Optically Active Lactones via Enzymatic ResolutionEnzymatic resolution of racemic gama-undecalactone and gama-decalactone has been effectively studied by means of the lipase selectively catalyzed hydrolysis reaction. The influence factors such as temperature, pH value and the amounts of the lipase were optimised. Employment of the aqueous solution of calcium chloride containing gum arabic as the reaction medium, improved the ee of the resolution product. The gama-hydroxy acid formed in the resolution was recovered, racemized, lactonized and recycled in the next run, which improved the yield of the optically active lactone.2. Dynamic Kinetic Resolution of 2-Alkyl-β-Keto Aldehydes by Using Asymmetric Transfer HydrogenationAsymmetric transfer hydrogenation of a series of 2-alkyl-β-keto aldehydes 1a?1p using HCOOH:Et3N = 5:2 as the hydrogen source and (S,S)-TsDPEN based Ru (II) catalysts via dynamic kinetic resolution procceds to synthesize corresponding 2-alkyl-β-keto primary alcohols 2a?2p with good yields and moderate ee values. These reactions offer an alternative for the preparation of aldol type intermediates by a non aldol pathway.3. Dynamic Kinetic Resolution ofα-Tosyl Aldehydes by Using Asymmetric Transfer HydrogenationEnatioselective reduction ofα-tosyl aldehydes 10a?10n using HCOOH:Et3N = 5:2 system as the hydrogen source and (S,S)-TsDPEN based Ru (II) catalysts via dynamic kinetic resolution procceds to synthesize correspondingβ-tosyl primary alcohols 11a?11n with good yields and high enatioselectivities.