- Stereodivergent and stereoselective synthesis of cis-and trans-4-substituted prolinols
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- Stereoselective synthesis of 4-substituted prolinol derivatives has been developed. Thus, Suzuki-Miyaura cross-coupling of vinyl tritiate provided the common synthetic intermediates toward the stereodivergent synthesis of cis- and ira?s-4-substituted prolinols. These two kinds of target compounds were obtained by diastereoselective hydrogenation of the coupling products with Pd/C and Crabtree catalyst, respectively. In addition, the obtained 4-substituted prolinol was transformed to the corresponding proline derivative via oxidation in one step.
- Ando, Junki,Tazawa, Aoi,Ishizawa, Kohei,Tanaka, Minoru,Takamura, Hiroyoshi
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p. 188 - 199
(2019/07/31)
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- Evolution of Biocatalytic and Chemocatalytic C-H Functionalization Strategy in the Synthesis of Manzacidin C
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Because of their unique molecular architecture, the manzacidins have been the subject of intense synthetic efforts in the past two decades. Here, we describe two synthetic approaches toward manzacidin C that center on the enzymatic hydroxylation of unprotected l-leucine. This study also resulted in the discovery of novel synthetic methodologies, including a photocatalytic C-H azidation of unprotected amino acids. Additionally, we describe the use of hydroxylated l-leucine in the preparation of various densely substituted pyrrolidines.
- Zwick, Christian R.,Renata, Hans
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p. 7407 - 7415
(2018/05/29)
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- CARBOHYDRATE CONJUGATED RNA AGENTS AND PROCESS FOR THEIR PREPARATION
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This disclosure relates to an improved process for the preparation of carbohydrate conjugates. The disclosure also relates to carbohydrate conjugated iRNA agents comprising these carbohydrate conjugates, which have improved purity and are advantageous for the in vivo delivery of the iRNA agents.
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- HEPATITIS C VIRUS INHIBITORS
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This disclosure concerns novel compounds of Formula (I) as defined in the specification and compositions comprising such novel compounds. These compounds are useful antiviral agents, especially in inhibiting the function of the NS5A protein encoded by Hepatitis C virus (HCV). Thus, the disclosure also concerns a method of treating HCV related diseases or conditions by use of these novel compounds or a composition comprising such novel compounds
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- Highly efficient syntheses of azetidines, pyrrolidines, and indolines via palladium catalyzed intramolecular amination of C(sp3)-H and C(sp2)-H bonds at γ and δ positions
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Efficient methods have been developed to synthesize azetidine, pyrrolidine, and indoline compounds via palladium-catalyzed intramolecular amination of C-H bonds at the γ and δ positions of picolinamide (PA) protected amine substrates. These methods feature relatively a low catalyst loading, use of inexpensive reagents, and convenient operating conditions. Their selectivities are predictable. These methods highlight the use of unactivated C-H bond, especially the C(sp3)-H bond of methyl groups, as functional groups in organic synthesis.
- He, Gang,Zhao, Yingsheng,Zhang, Shuyu,Lu, Chengxi,Chen, Gong
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supporting information; experimental part
p. 3 - 6
(2012/02/16)
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- Asymmetric hydrogenations for the synthesis of boc-protected 4-alkylprolinols and prolines
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The utility of 4-substituted prolinols and their corresponding prolines in peptides, peptidomimetics, and natural products has motivated researchers to find new and efficient routes for their preparation. Herein, we report a general approach to the synthesis of Boc-protected 4-alkylprolinols and prolines via a divergent asymmetric hydrogenation strategy. Intermediate exocyclic olefins were prepared by Wittig-type reactions with ketone 6 and subjected to hydroxyl and sterically directed reductions. The Crabtree catalyst (Ir[COD] PyPCy3PF6) proved to be highly effective in diastereoselective hydrogenations to give trans- substituted pyrrolidines (9). Good facial selectivities were also observed in heterogeneous hydrogenations with Raney-nickel to obtain cis-substituted pyrrolidines (11). Employing this strategy, we describe the synthesis of novel prolinol and proline-based building blocks for incorporation into biologically relevant peptidomimetics.
- Del Valle, Juan R.,Goodman, Murray
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p. 3923 - 3931
(2007/10/03)
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- Asymmetric synthesis of 4-substituted prolines as conformationally constrained amino acid analogues
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Treatment of readily available chiral building block 1 with (2R)-2,3-O- isopropylideneglyceraldehyde (5) provides a new route for asymmetric synthesis of 2,4-disubstituted pyrrolidines. Several proline-amino acid chimeras: proline-leucine, proline-lysine, proline-arginine and proline- glutamic acid, are synthesized in highly diastereomerically pure forms.
- Wang, Qian,Sasaki, N. Andre,Potier, Pierre
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p. 15759 - 15780
(2007/10/03)
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