Chiral Syn-1,3-diol Derivatives via a One-Pot Diastereoselective Carboxylation/ Bromocyclization of Homoallylic Alcohols

Manganese/Enzyme Sequential Catalytic Pathway for the Production of Optically Active γ-Functionalized Alcohols

A brief, practical catalytic process for the production of optically active γ-functionalized alcohols from relevant alkenes has been developed by using a robust Mn(III)/air/(Me2SiH)2O catalytic system combined with lipase-catalyzed kinetic resolution. This approach demonstrates exceptional tolerance toward proximal functional groups present on alkenes, enabling the achievement of high yields and exclusive enantioselectivity. Under this sequential catalytic system, the chiral alkene precursors can also be converted into γ-functionalized alcohols and related acetates as separable single enantiomers.

Enantioseparation in Hierarchically Porous Assemblies of Homochiral Cages

Efficient enantioselective separation using porous materials requires tailored and diverse pore environments to interact with chiral substrates; yet, current cage materials usually feature uniform pores. Herein, we report two porous assemblies, PCC-60 and PCC-67, using isostructural octahedral cages with intrinsic microporous cavities of 1.5 nm. The PCC-67 adopts a densely packed mode, while the PCC-60 is a hierarchically porous assembly featuring interconnected 2.4 nm mesopores. Compared with PCC-67, the PCC-60 demonstrates excellent enantioselectivity and recyclability in separating racemic diols and amides. This solid adsorbent PCC-60 is further utilized as a chiral stationary phase for high-performance liquid chromatography (HPLC), enabling the complete separation of six valuable pharmaceutical intermediates. According to quantitative dynamic experiments, the hierarchical pores facilitate the mass transfer within the superstructure, shortening the equilibrium time for adsorbing chiral substrates. Notably, this hierarchically porous material PCC-60 indicates remarkably higher enantiomeric excess (ee) values in separating racemates than PCC-67 with uniform microporous cavities. Control experiments confirm that the presence of mesopores enables the PCC-60 to separate bulky substrates. These results uncover the traditionally underestimated role of hierarchical porosity in porous-superstructure-based enantioseparation.

Application of Ketoreductase in Asymmetric Synthesis of Pharmaceuticals and Bioactive Molecules: An Update (2018-2020)

With the rapid development of genomic DNA sequencing, recombinant DNA expression, and protein engineering, biocatalysis has been increasingly and widely adopted in the synthesis of pharmaceuticals, bioactive molecules, fine chemicals, and agrochemicals. In this review, we have summarized the most recent advances achieved (2018-2020) in the research area of ketoreductase (KRED)-catalyzed asymmetric synthesis of chiral secondary alcohol intermediates to pharmaceuticals and bioactive molecules. In the first part, synthesis of chiral alcohols with one stereocenter through the bioreduction of four different ketone classes, namely acyclic aliphatic ketones, benzyl or phenylethyl ketones, cyclic aliphatic ketones, and aryl ketones, is discussed. In the second part, KRED-catalyzed dynamic reductive kinetic resolution and reductive desymmetrization are presented for the synthesis of chiral alcohols with two contiguous stereocenters.

Catalytic asymmetric aldehyde prenylation and application in the total synthesis of (-)-rosiridol and (-)-bifurcadiol

Chiral phosphoric acid-catalyzed asymmetric aldehyde prenylation has been established using an α,α-dimethyl allyl boronic ester. The transformation provides expedient access to a wide array of aryl, heteroaryl, aryl-substituted alkenyl and primary and secondary aliphatic homoprenyl alcohols with excellent asymmetric induction. The utility of this asymmetric catalysis strategy has been demonstrated through a short and efficient total synthesis of the two natural products (-)-rosiridol and (-)-bifurcadiol.