- Enzymatic Primary Amination of Benzylic and Allylic C(sp3)-H Bonds
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Aliphatic primary amines are prevalent in natural products, pharmaceuticals, and functional materials. While a plethora of processes are reported for their synthesis, methods that directly install a free amine group into C(sp3)-H bonds remain unprecedented. Here, we report a set of new-to-nature enzymes that catalyze the direct primary amination of C(sp3)-H bonds with excellent chemo-, regio-, and enantioselectivity, using a readily available hydroxylamine derivative as the nitrogen source. Directed evolution of genetically encoded cytochrome P411 enzymes (P450s whose Cys axial ligand to the heme iron has been replaced with Ser) generated variants that selectively functionalize benzylic and allylic C-H bonds, affording a broad scope of enantioenriched primary amines. This biocatalytic process is efficient and selective (up to 3930 TTN and 96percent ee), and can be performed on preparative scale.
- Jia, Zhi-Jun,Gao, Shilong,Arnold, Frances H.
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supporting information
p. 10279 - 10283
(2020/07/27)
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- Chemistry of N-Boc-N-tert-butylthiomethyl-protected alpha-aminoorganostannanes: diastereoselective synthesis of primary beta-amino alcohols from alpha-aminoorganostannanes.
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Reaction of N-Boc-N-tert-butylthiomethyl-protected alpha-aminoorganostannanes with n-BuLi generates the corresponding alpha-aminoorganolithiums. Reactions of these organolithiums with aromatic aldehydes provides N-protected beta-amino alcohols with diastereoselectivities up to >99:1 anti/syn; with aliphatic aldehydes, diastereoselectivities were typically 1:1. Diastereoselectivities varied depending on the amount of aldehyde used. The N-protected beta-amino alcohols could be deprotected to primary amines by treatment with NaH to generate oxazolidinones followed by basic hydrolysis. Alternatively, treatment of the protected amino alcohols with acid furnished cyclic acetals that could be deprotected to primary amines with BF(3).OEt(2) and HS(CH(2))(3)SH. Transmetalation of enantiomerically enriched organostannanes with n-BuLi at -95 degrees C provided organolithiums that, although less configurationally stable than N-Boc-N-methyl-protected alpha-aminoorganolithiums, could be trapped with aldehydes with near-complete retention of configuration.
- Ncube, Adela,Park, Sheldon B,Chong, J Michael
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p. 3625 - 3636
(2007/10/03)
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- Process for producing optically active 3,3,3-Trifluoro-2-Hydroxy-2-Methylpropionic acid, and salt thereof
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There are disclosed are a diastereomer salt of formula (1): a process for producing the same, a process for producing optically active 3,3,3-trifluoro-2-hydroxy-2-methylpropionic acid of formula (2′): a novel optically active amine compound of formula (4): a novel optically active amine compound of formula (8): an imine compound of formula (7) or (11):
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- Method for producing optically active amines
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A method for producing an optically active amine which is an important compound as a resolving agent for medicines, agricultural chemicals, intermediates thereof, etc is disclosed.
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- TRANSFER HYDROGENATION: A STEREOSPECIFIC METHOD FOR THE CONVERSION OF NITRO ALKANES INTO AMINES
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A series of nitro alkanes were converted into the corresponding amines with retention of configuration by transfer hydrogenation using ammonium formate and palladium on carbon.
- Barrett, Anthony G. M.,Spilling, Christopher D.
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p. 5733 - 5734
(2007/10/02)
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- Diastereoselective Synthesis of Nitroaldol Derivatives
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Three methods are described by which diastereomerically enriched nitroaldols and their O-silylated derivatives can be prepared. threo-Nitroaldols prevail up to 10:1 over the erythro-isomers if doubly deprotonated nitroaldols 28 are quenched with acetic acid (THF/HMPT or DMPU, -100 deg C) (see Scheme 5 and Table 2).O-Trimethyl- or O-(t-butyl)dimethylsilylated (TBDMSi) erythro-nitroaldols can be obtained by protonation of the corresponding lithium nitronates (35, 39) in THF at low temperature (see Schemes 6 and 7).The erythro-O-TBDMSi-nitroaldol derivatives are also formed in the fluoride catalyzed addition of TBDMSi-nitronates (40-45) to aldehydes (see Schemes 8 and 9).In the latter reaction no 1,2-asymmetric induction is observed if α-branched silylnitronates or aldehydes are employed (see 48/49 and 50/51). - The stereochemical course of the reactions leading to erythro-O-TBDMSi-nitroaldols follows topological rules of broad applicability (see Scheme 10); possible mechanisms are discussed.- The configuration of erythro/threo-nitroaldols is determined by chemical correlation (see 24-26) and by 13C-NMR. spectroscopy. - Some examples of the preparation of diastereomerically enriched 1,2-aminoalcohols by reduction of the corresponding nitro compounds without loss of configurational purity are described (see Schemes 11 and 12).
- Seebach, Dieter,Beck, Albert K.,Mukhopadhyay, Triptikumar,Thomas, Elizabeth
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p. 1101 - 1133
(2007/10/02)
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- 3-Hydroxy-4-nitro-cyclohexanones from Ketones and 4-Nitrobutanoyl Chloride. A Ring Enlarging Five-Ring Annulation
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The 6-nitro-1,3-diketones 5, 8, 9, 10, and 11, prepared by a 1:1 acylation at the C-atom of non-hindered lithium enolates with 4-nitrobutanoyl chloride according to equation 3, are cyclized with sodium hydrogen carbonate in aqueous tetrahydrofuran to give the hydroxy-nitro-ketones 13-17.Such cyclic nitroaldols are not formed from the cyclopentanone, -heptanone, and -octanone, nor from the aryl derivatives 4, 6, 7 and 12, respectively.Except for the vicinally trisubstituted compound 14, the cyclization products are isolated in diastereomerically pure form.A crystal structure X-ray analysis reveals the trans-decalone and the cis-β-nitroalcohol configurations of the product 13 from cyclohexanone.Acetalization to 21-25 and catalytic hydrogenation of the nitro groups furnishes the amino alcohols 27-31 which are substrates for the Tiffeneau-Demjanow rearrangement.From the stereoelectronic control of this sextett rearrangement we deduce the configurations of the 1,4-diketones 35, 36, 39, 40, 43, 44, 46, and 47 formed under kinetic or thermodynamic conditions.The six-ring annulation with nitrobutanoic acid and the subsequent rearrangement are shown in Scheme 6; the sequence of reactions described here allows to carry out a ring enlargement of a cyclic ketone by one C-atom, with simultaneous annulation of a cyclopentanone ring.
- Weller, Thomas,Seebach, Dieter,Davis, Raymond E.,Laird, Brian B.
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p. 736 - 760
(2007/10/02)
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