Acid-labile δ-ketal-β-hydroxy esters by asymmetric hydrogenation of corresponding δ-ketal-β-keto esters in the presence of CaCO3.
نویسندگان
چکیده
A series of acid-labile, optically pure ε-substituted δ-ketal-β-hydroxy esters were obtained by a Ru-SunPhos catalyzed asymmetric hydrogenation of the corresponding ε-substituted δ-ketal-β-keto esters. CaCO(3) played a dual role in the hydrogenation reaction--removing the acid generated during the formation of the catalyst and maintaining the activity of the catalyst.
منابع مشابه
Ru-catalyzed highly chemo- and enantioselective hydrogenation of γ-halo-γ,δ-unsaturated-β-keto esters under neutral conditions.
Finely-tuned ruthenium-catalyzed highly chemoselective and enantioselective hydrogenation of γ-halo-γ,δ-unsaturated-β-keto esters at the carbonyl group was achieved under neutral reaction conditions (ee up to 97%). Both olefin and alkenyl halogen moieties, which are labile under hydrogenation conditions, remained untouched during the reaction.
متن کاملFacile synthesis of chiral alpha-difluoromethyl amines from N-(tert-butylsulfinyl)aldimines.
Fluorinated amines are important synthetic building blocks in the design of antimetabolites and drugs because fluorine causes minimal structural changes and maximal shifts in electron distribution. Fluorine lowers the basicity of amines and improves oral absorption, suppresses metabolism, and thus increases the bioavailability of a target drug. Among the fluorinated amines, a-difluoromethyl ami...
متن کاملChemoenzymatic Synthesis of trans-β-Aryl-δ-hydroxy-γ-lactones and Enzymatic Kinetic Resolution of Their Racemic Mixtures.
Two novel and convenient routes to obtain enantiomerically enriched trans-β-aryl-δ-hydroxy-γ-lactones 5a-d with potential antifeedant and anticancer activity were developed. In the first method starting from corresponding enantiomers of γ,δ-unsaturated esters 4a-d derived from enzymatically resolved allyl alcohols 1a-d, both enantiomers of hydroxylactones 5a-d were synthesized with high enantio...
متن کاملCopper-catalyzed cascade reactions of α,β-unsaturated esters with keto esters
A copper-catalyzed cascade reaction of α,β-unsaturated esters with keto esters is reported. It features a copper-catalyzed reductive aldolization followed by a lactonization. This method provides a facile approach to prepare γ-carboxymethyl-γ-lactones and δ-carboxymethyl-δ-lactones under mild reaction conditions.
متن کامل[Natural products syntheses based on the biotransformation using biocatalyst].
This review summarizes the chemoenzymatic synthesis of the biologically active natural products based on a combination of chemical diastereoselectivity and enzymatic enantioselectivity using biocatalyst. Asymmetric reduction of 2-methyl-3-keto ester with yeast gave the optically active syn-2-methyl-3-hydroxy ester, which was converted to natural product such as (-)-oudemansin B. Asymmetric hydr...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- Chemical communications
دوره 48 35 شماره
صفحات -
تاریخ انتشار 2012