One-Pot Synthesis of Chiral N-Arylamines by Combining Biocatalytic Aminations with Buchwald–Hartwig N-Arylation

The combination of biocatalysis and chemo-catalysis increasingly offers chemists access to more diverse chemical architectures. Here, we describe the combination of a toolbox of chiral-amine-producing biocatalysts with a Buchwald–Hartwig cross-coupling reaction, affording a variety of α-chiral aniline derivatives. The use of a surfactant allowed reactions to be performed sequentially in the same flask, preventing the palladium catalyst from being inhibited by the high concentrations of ammonia, salts, or buffers present in the aqueous media in most cases. The methodology was further extended by combining with a dual-enzyme biocatalytic hydrogen-borrowing cascade in one pot to allow for the conversion of a racemic alcohol to a chiral aniline.     

Carrier Protein-Free Enzymatic Biaryl Coupling in Arylomycin A2 Assembly and Structure of the Cytochrome P450 AryC**

The arylomycin antibiotics are potent inhibitors of bacterial type I signal peptidase. These lipohexapeptides contain a biaryl structural motif reminiscent of glycopeptide antibiotics. We herein describe the functional and structural evaluation of AryC, the cytochrome P450 performing biaryl coupling in biosynthetic arylomycin assembly. Unlike its enzymatic counterparts in glycopeptide biosynthesis, AryC converts free substrates without the requirement of any protein interaction partner, likely enabled by a strongly hydrophobic cavity at the surface of AryC pointing to the substrate tunnel. This activity enables chemo-enzymatic assembly of arylomycin A2 that combines the advantages of liquid- and solid-phase peptide synthesis with late-stage enzymatic cross-coupling. The reactivity of AryC is unprecedented in cytochrome P450-mediated biaryl construction in non-ribosomal peptides, in which peptidyl carrier protein (PCP)-tethering so far was shown crucial both in vivo and in vitro.     

GPhos Ligand Enables Production of Chiral N-Arylamines in a Telescoped Transaminase-Buchwald-Hartwig Amination Cascade in the Presence of Excess Amine Donor

The combination of biocatalysis and chemocatalysis can be more powerful than either technique alone. However, combining the two is challenging due to typically very different reaction conditions. Herein, chiral N-aryl amines, key features of many active pharmaceutical ingredients, are accessed in excellent enantioselectivity (typically>99.5 % ee) by combining transaminases with the Buchwald-Hartwig amination. By employing a bi-phasic buffer-toluene system as well as the ligand GPhos, the telescoped cascade proceeded with up to 89 % overall conversion in the presence of excess alanine. No coupling to alanine was observed.     

Assembly of Nano-Biocatalyst for the Tandem Hydrolysis and Reduction of p-Nitrophenol Esters

Hybrid nano-biomaterials are exploited in the design and performance of chemo-enzymatic cascades. In this study, lipase is immobilized from Candida antarctica fraction B (CALB) and gold nanoparticles (Au NPs) on magnetic particles coated with silica (MNP@SiO₂) to stepwise hydrolyze and reduce p-nitrophenyl esters in tandem reaction. The assembly of the two catalysts at the interface of the MNP@SiO₂ particles and the temporal control of the reaction turns out to be the most determinant parameters for the cascade kinetics. When both CALB and Au NPs are co-immobilized at the MNP@SiO₂ particle, the tandem reactions take place significantly faster than when both catalysts are physically segregated by their immobilization on different MNP@SiO₂ particles. Herein, it is demonstrated that the co-immobilization of biocatalysts and nanocatalysts in solid materials creates hybrid interfaces that accelerated chemo-enzymatic tandem reactions.     

Synthesis and Characterization of Novel Amphiphilic Polymers as Drug Delivery Nano Carriers

Polymer nano-particles have been widely investigated in the last decade due to a variety of potential applications. In particular, polymers which can self assemble into micellar nano-particles can be effectively used as vehicles for drug delivery. Considerable efforts are underway to develop better drug delivery nano carriers for high drug loading capacity for a wide variety of bioactive compounds. In this study, several new polymers were synthesized in bulk (solventless condition) by a chemo-enzymatic methodology using Candida antarctica lipase B (Novozyme 435) and molecular sieves (MS). The synthesized polymers demonstrated high drug loading capacity and the potential to encapsulate drugs which are poorly soluble in aqueous solvents.     

酶促-化学法合成(R)-N-苄基吗啉-3-酮-2-乙酰(4-脒基)苄胺

报道了一种酶促-化学法合成光学纯吗啉酮凝血酶抑制剂的新途径.以马来酸酐和氨基醇为起始原料,一锅法合成N-苄基吗啉-3-酮-2-乙酸甲酯;再用脂肪酶CAL-B在甲基叔丁基醚/水（体积分数=1/9）混合溶剂中将其选择性水解,制备光学纯（R）-N-苄基吗啉-3-酮-2-乙酸;经过酰胺化、还原/胺解,得到（R）-N-苄基吗啉-3-酮-2-乙酰（4-脒基）苄胺;所得化合物结构经IR,1H NMR,13C NMR表征确证.文中还讨论了酶源、溶剂、含水量、反应时间等因素对水解拆分的影响.     

Chemo‐Enzymatic Synthesis of Position‐Specifically Modified RNA for Biophysical Studies including Light Control and NMR Spectroscopy

The investigation of non‐coding RNAs requires RNAs containing modifications at every possible position within the oligonucleotide. Here, we present the chemo‐enzymatic RNA synthesis containing photoactivatable or ¹³C,¹⁵N‐labelled nucleosides. All four ribonucleotides containing ortho‐nitrophenylethyl (NPE) photocages, photoswitchable azobenzene C‐nucleotides and ¹³C,¹⁵N‐labelled nucleotides were incorporated position‐specifically in high yields. We applied this approach for the synthesis of light‐inducible 2′dG‐sensing riboswitch variants and detected ligand‐induced structural reorganization upon irradiation by NMR spectroscopy. This chemo‐enzymatic method opens the possibility to incorporate a wide range of modifications at any desired position of RNAs of any lengths beyond the limits of solid‐phase synthesis.     

One‐Pot Synthesis of Chiral N‐Arylamines by Combining Biocatalytic Aminations with Buchwald–Hartwig N‐Arylation

The combination of biocatalysis and chemo‐catalysis increasingly offers chemists access to more diverse chemical architectures. Here, we describe the combination of a toolbox of chiral‐amine‐producing biocatalysts with a Buchwald–Hartwig cross‐coupling reaction, affording a variety of α‐chiral aniline derivatives. The use of a surfactant allowed reactions to be performed sequentially in the same flask, preventing the palladium catalyst from being inhibited by the high concentrations of ammonia, salts, or buffers present in the aqueous media in most cases. The methodology was further extended by combining with a dual‐enzyme biocatalytic hydrogen‐borrowing cascade in one pot to allow for the conversion of a racemic alcohol to a chiral aniline.     

Chemo-enzymatic synthesis of the human angiogenin gene. Construction of bacterial strains,producers of human angiogenin. Elaboration of a technology for the purification and preparation of angiogenin

Chemo-enzymatic synthesis of the gene of human angiogenin, a stimulator of blood vessel growth, was performed for the first time. Cloning of the human angiogenin gene in several expressing vector systems was carried out, and several bacterial strains, producers of human angiogenin were constructed. In particular, strains, producers of angiogenin--galactosidase and angiogenin-domains of staphylococcal protein A hybrid proteins were obtained, as well as a bacterial strain efficiently expressing free angiogenin. Large-scale preparation of purified recombinant human angiogenin was accomplished using theE.coli JM103 pRITA16 producer strain constructed, and the biological activity of the resulting preparation was studied.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12. pp. 2837–2846, December, 1996.     

New chemo and chemo-enzymatic synthesis of β-benzyl-γ-butyrolactones

β-Benzyl-γ-butyrolactones, important intermediates for the synthesis of butyrolactone lignans, have been synthesized by a new route involving preparation of α-β-unsaturated formyl esters. The formyl esters can easily be converted into the desired butyrolactones either through chemical transformations or by enzymatic methods.