63328-11-0Relevant articles and documents
SYNTHESIS AND APPLICATION OF CHIRAL SUBSTITUTED POLYVINYLPYRROLIDINONES
-
, (2020/11/24)
Chiral polyvinylpyrrolidinone (CSPVP), complexes of CSPVP with a core species, such as a metallic nanocluster catalyst, and enantioselective oxidation reactions utilizing such complexes are disclosed. The CSPVP complexes can be used in asymmetric oxidation of diols, enantioselective oxidation of alkenes, and carbon-carbon bond forming reactions, for example. The CSPVP can also be complexed with biomolecules such as proteins, DNA, and RNA, and used as nanocarriers for siRNA or dsRNA delivery.
Iridium-Catalyzed Enantioselective C(sp3)-H Amidation Controlled by Attractive Noncovalent Interactions
Wang, Hao,Park, Yoonsu,Bai, Ziqian,Chang, Sukbok,He, Gang,Chen, Gong
supporting information, p. 7194 - 7201 (2019/05/10)
While remarkable progress has been made over the past decade, new design strategies for chiral catalysts in enantioselective C(sp3)-H functionalization reactions are still highly desirable. In particular, the ability to use attractive noncovalent interactions for rate acceleration and enantiocontrol would significantly expand the current arsenal for asymmetric metal catalysis. Herein, we report the development of a highly enantioselective Ir(III)-catalyzed intramolecular C(sp3)-H amidation reaction of dioxazolone substrates for synthesis of optically enriched γ-lactams using a newly designed α-amino-acid-based chiral ligand. This Ir-catalyzed reaction proceeds with excellent efficiency and with outstanding enantioselectivity for both activated and unactivated alkyl C(sp3)-H bonds under very mild conditions. It offers the first general route for asymmetric synthesis of γ-alkyl γ-lactams. Water was found to be a unique cosolvent to achieve excellent enantioselectivity for γ-aryl lactam production. Mechanistic studies revealed that the ligands form a well-defined groove-type chiral pocket around the Ir center. The hydrophobic effect of this pocket allows facile stereocontrolled binding of substrates in polar or aqueous media. Instead of capitalizing on steric repulsions as in the conventional approaches, this new Ir catalyst operates through an unprecedented enantiocontrol mechanism for intramolecular nitrenoid C-H insertion featuring multiple attractive noncovalent interactions.
Chiral-Substituted Poly-N-vinylpyrrolidinones and Bimetallic Nanoclusters in Catalytic Asymmetric Oxidation Reactions
Hao, Bo,Gunaratna, Medha J.,Zhang, Man,Weerasekara, Sahani,Seiwald, Sarah N.,Nguyen, Vu T.,Meier, Alex,Hua, Duy H.
, p. 16839 - 16848 (2017/01/10)
A new class of poly-N-vinylpyrrolidinones containing an asymmetric center at C5 of the pyrrolidinone ring were synthesized from l-amino acids. The polymers, particularly 17, were used to stabilize nanoclusters such as Pd/Au for the catalytic asymmetric oxidations of 1,3- and 1,2-cycloalkanediols and alkenes, and Cu/Au was used for C-H oxidation of cycloalkanes. It was found that the bulkier the C5 substituent in the pyrrolidinone ring, the greater the optical yields produced. Both oxidative kinetic resolution of (±)-1,3- and 1,2-trans-cycloalkanediols and desymmetrization of meso cis-diols took place with 0.15 mol % Pd/Au (3:1)-17 under oxygen atmosphere in water to give excellent chemical and optical yields of (S)-hydroxy ketones. Various alkenes were oxidized with 0.5 mol % Pd/Au (3:1)-17 under 30 psi of oxygen in water to give the dihydroxylated products in >93% ee. Oxidation of (R)-limonene at 25 °C occurred at the C-1,2-cyclic alkene function yielding (1S,2R,4R)-dihydroxylimonene 49 in 92% yield. Importantly, cycloalkanes were oxidized with 1 mol % Cu/Au (3:1)-17 and 30% H2O2 in acetonitrile to afford chiral ketones in very good to excellent chemical and optical yields. Alkene function was not oxidized under the reaction conditions. Mechanisms were proposed for the oxidation reactions, and observed stereo- and regio-chemistry were summarized.
Catalytic enantioselective Steglich rearrangements using chiral N-heterocyclic carbenes
Campbell, Craig D.,Concellon, Carmen,Smith, Andrew D.
experimental part, p. 797 - 811 (2011/08/06)
The evaluation of a range of enantiomerically pure NHCs, prepared in situ from imidazolinium or triazolium salt precatalysts, to promote the catalytic enantioselective Steglich rearrangement of oxazolyl carbonates to their C-carboxyazlactones, is reported. Modest levels of enantioselectivity (up to 66% ee) are observed using oxazolidinone derived NHCs.
An efficient synthesis of achiral and chiral 1,2,4-triazolium salts: Bench stable precursors for N-heterocyclic carbenes
Kerr, Mark S.,Read De Alaniz, Javier,Rovis, Tomislav
, p. 5725 - 5728 (2007/10/03)
The promising utility of triazolyl N-heterocyclic carbene catalysts in umpolung aldehyde chemistry requires a straight-forward reliable synthesis from readily available materials. Herein, we describe the synthesis of a variety of triazolyl N-heterocyclic
Asymmetric synthesis of 5-arylmethylpyrrolidin-2-ones and 2-arylmethylpyrrolidines
Lebrun, Stephane,Couture, Axel,Deniau, Eric,Grandclaudon, Pierre
, p. 2625 - 2632 (2007/10/03)
An efficient methodology for the enantioselective synthesis of 5-arylmethylpyrrolidin-2-ones and 2-arylmethylpyrrolidines has been devised. The key step is the stereoselective hydrogenation of the N-acylhydrazonium salts obtained from the corresponding arylmethylene hydrazides. These highly conjugated compounds are readily prepared by reacting a chiral succinimide with a variety of arylmethyl Grignard reagents. Removal of the chiral auxiliary and subsequent reduction complete the synthesis of the title compounds.
Design and synthesis of novel conformationally restricted HIV protease inhibitors
Salituro, Francesco G.,Baker, Christopher T.,Court, John J.,Deininger, David D.,Kim, Eunice E.,Li, Biquin,Novak, Perry M.,Rao, Bhisetti G.,Pazhanisamy,Porter, Margaret D.,Schairer, Wayne C.,Tung, Roger D.
, p. 3637 - 3642 (2007/10/03)
A set of HIV protease inhibitors represented by compound 2 has previously been described. Structural and conformational analysis of this compound suggested that conformational restriction of the P1/P2 portion of the molecule could lead to a novel set of potent protease inhibitors. Thus, probe compounds 3-7 were designed, synthesized, and found to be potent inhibitors of HIV protease.
12. Approaches to the Synthesis of Cytochalasans; Part 9: A Versatile Concept Leading To All Structural Types of Cytochalasans
Ackermann, Jean,Matthes, Michael,Tamm, Christoph
, p. 122 - 132 (2007/10/02)
Starting from D-glutamic acid (5), the bicyclic compounds 4a and 4b were synthesized via 17 (Schemes 1 and 2).The reaction leading to 4g and 4h with LiCuPh2 was not successful.But treatment of the N-protected model lactams 19, 21, and 22 with Li2Cu(CN)Ph2 gave the amino ketones 24, 26, and 26, respectively (Scheme 3).The desired compound 23 was obtained from 20.Conversion of the unprotected lactams 28, 31, and 32 gave the phenyl derivative 34 in excellent yields.Ester 35 was transformed to the α-amino-γ-oxo-acid derivative 36.This conversion opens a novel access to this type of compounds.
