Combined batch and continuous flow procedure to the chemo-enzymatic synthesis of biaryl moiety of Odanacatib

One-pot chemo- and photo-enzymatic linear cascade processes

The combination of chemo- and photocatalyses with biocatalysis, which couples the flexible reactivity of the photo- and chemocatalysts with the highly selective and environmentally friendly nature of enzymes in one-pot linear cascades, represents a powerful tool in organic synthesis. However, the combination of photo-, chemo- and biocatalysts in one-pot is challenging because the optimal operating conditions of the involved catalyst types may be rather different, and the different stabilities of catalysts and their mutual deactivation are additional problems often encountered in one-pot cascade processes. This review explores a large number of transformations and approaches adopted for combining enzymes and chemo- and photocatalytic processes in a successful way to achieve valuable chemicals and valorisation of biomass. Moreover, the strategies for solving incompatibility issues in chemo-enzymatic reactions are analysed, introducing recent examples of the application of non-conventional solvents, enzyme-metal hybrid catalysts, and spatial compartmentalization strategies to implement chemo-enzymatic cascade processes.

Efficient Synthesis of Chiral Aryl Alcohol with a Novel Kosakonia radicincitans Isolate in Tween 20/L-carnitine: Lysine-Containing Synergistic Reaction System

Chiral trifluoromethyl alcohols as vital intermediates are of great interest in fine chemicals and especially in pharmaceutical synthesis. In this work, a novel isolate Kosakonia radicincitans ZJPH202011 was firstly employed as biocatalyst for the synthesis of (R)-1-(4-bromophenyl)-2,2,2-trifluoroethanol ((R)-BPFL) with good enantioselectivity. By optimizing fermentation conditions and bioreduction parameters in aqueous buffer system, the substrate concentration of 1-(4-bromophenyl)-2,2,2-trifluoroethanone (BPFO) was doubled from 10 to 20 mM, and the enantiomeric excess (ee) value for (R)-BPFL increased from 88.8 to 96.4%. To improve biocatalytic efficiency by strengthening the mass-transfer rate, natural deep-eutectic solvents, surfactants and cyclodextrins (CDs) were introduced separately in the reaction system as cosolvent. Among them, L-carnitine: lysine (C: Lys, molar ratio 1:2), Tween 20 and γ-CD manifested higher (R)-BPFL yield compared with other same kind of cosolvents. Furthermore, based on the excellent performance of both Tween 20 and C: Lys (1:2) in enhancing BPFO solubility and ameliorating cell permeability, a Tween 20/C: Lys (1:2)-containing integrated reaction system was then established for efficient bioproduction of (R)-BPFL. After optimizing the critical factors involved in BPFO bioreduction in this synergistic reaction system, BPFO loading increased up to 45 mM and the yield reached 90.0% within 9 h, comparatively only 37.6% yield was acquired in neat aqueous buffer. This is the first report on K. radicincitans cells as new biocatalyst applied in (R)-BPFL preparation, and the developed Tween 20/C: Lys-containing synergistic reaction system has great potential for the synthesis of various chiral alcohols.

Asymmetric hydrogenation of trifluoromethyl ketones: application in the synthesis of Odanacatib and LX-1031

The asymmetric hydrogenation of trifluoromethyl ketones via iridium catalysis to access chiral secondary 2,2,2-trifluoroethanols is presented. The key intermediates of Odanacatib and LX1301 were prepared with high yields and enantioselectivities.

Studies on the dynamic resolution of Crizotinib intermediate

Crizotinib is an anti-cancer agent approved for treatment of non-small cell lung carcinoma. Retrosynthetic analysis revels 1-(2,6-dichloro-3-fluorophenyl)ethanol as an important intermediate, which can be made available by different biocatalytic approaches. Herein we report our results on the kinetic and dynamic resolution towards the desired chiral intermediate for Crizotinib synthesis. The results obtained show that very good conversions and high selectivity could be obtained for the kinetic resolution (45% conv. and E>200) while dynamic kinetic resolution under continuous-flow conditions afforded the desired product in 57% conversion and 98% e.e.

The Hitchhiker's Guide to Flow Chemistry ∥

Flow chemistry involves the use of channels or tubing to conduct a reaction in a continuous stream rather than in a flask. Flow equipment provides chemists with unique control over reaction parameters enhancing reactivity or in some cases enabling new reactions. This relatively young technology has received a remarkable amount of attention in the past decade with many reports on what can be done in flow. Until recently, however, the question, "Should we do this in flow?" has merely been an afterthought. This review introduces readers to the basic principles and fundamentals of flow chemistry and critically discusses recent flow chemistry accounts.

Silva MV, Dias FC, de Souza SP, Leão RAC, de Souza ROMA. Continuous flow dynamic kinetic resolution of rac-1-phenylethanol using a single packed-bed containing immobilized CAL-B lipase and VOSO4 as racemization catalysts

Herein, we report a method for the continuous flow DKR of rac-1-phenylethanol catalyzed by CAL-B and VOSO₄, using a single packed-bed containing both catalysts.

Alves L, Brocksom TJ, de Oliveira KT. Combining batch and continuous flow setups in the end-to-end synthesis of naturally occurring curcuminoids

A successful end-to-end continuous flow synthesis of pure curcumin (1) and two other natural derivatives present in turmeric is described.