Klebsiellapneumoniae (NBRC 3319) Mediated Asymmetric Reduction of α‐Substituted β‐Oxo Esters and Its Application to the Enantioiselective Synthesis of Small‐Ring Carbocycle Derivatives

Abstract

Ketoreductases from Klebsiella pneumoniae (NBRC 3319) selectively reduce several 2-substituted ethyl 3-oxobutyrates to yield the corresponding syn-β-hydroxy esters with remark-

Versatile Iridicycle Catalysts for Highly Efficient and Chemoselective Transfer Hydrogenation of Carbonyl Compounds in Water

“…To showcase the broader utility of the catalytic system, we also applied C4 to the reduction of keto esters 6a. d, i, 19 Both aromatic and aliphatic β‐keto esters were reduced to afford the corresponding alcohols with excellent yields under the catalysis of 0.1 mol % of C4 (Table 4).…”

“…The reduction of α‐substituted ketones to form β‐functionalised secondary alcohols has drawn a lot of attention in the last two decades, due to the products being ubiquitous in naturally occurring and synthetic bioactive compounds 6. For example, β‐hydroxyethers have been used as biological probes and synthetic intermediates for molecular switches 6a–c. k, m, 7 β‐Aminoethers can be readily derived from β‐hydroxyethers and are important precursors in the preparation of a wide variety of pharmaceutical compounds 6a–c.…”

“…For example, β‐hydroxyethers have been used as biological probes and synthetic intermediates for molecular switches 6a–c. k, m, 7 β‐Aminoethers can be readily derived from β‐hydroxyethers and are important precursors in the preparation of a wide variety of pharmaceutical compounds 6a–c. k, m A further example is found in β‐hydroxyamines, which have been demonstrated as building blocks in many synthetic methodologies leading to various bioactive compounds, including, for example, medicines that affect the central nervous and respiratory systems (Scheme ) 6a–e.…”

“…k, m, 7 β‐Aminoethers can be readily derived from β‐hydroxyethers and are important precursors in the preparation of a wide variety of pharmaceutical compounds 6a–c. k, m A further example is found in β‐hydroxyamines, which have been demonstrated as building blocks in many synthetic methodologies leading to various bioactive compounds, including, for example, medicines that affect the central nervous and respiratory systems (Scheme ) 6a–e. k–p Of further interest are β‐hydroxyhalo compounds, which have found use in the preparation of numerous compounds for pharmaceuticals, fine chemicals and functional materials 6b.…”

“…Given the versatility of the α‐substituted ketones, a number of reagents and methods have been developed for their selective reduction, especially the asymmetric version 6a–m. 8 However, few catalysts are known that are capable of selective TH of a wide range of α‐substituted ketones 6a–i. l–m, 9 In addition, most of the reactions are conducted in organic solvents, which generates unwanted waste.…”