A5101992280- Asymmetric Hydrogenation and Catalysis
- Asymmetric Synthesis and Catalysis
- Catalytic C–H Functionalization Methods
- Catalytic Cross-Coupling Reactions
- Axial and Atropisomeric Chirality Synthesis
- Chemical Synthesis and Analysis
- Synthetic Organic Chemistry Methods
- Chemical Reactions and Isotopes
- Surface Chemistry and Catalysis
- Molecular spectroscopy and chirality
- Chemical synthesis and alkaloids
- Catalytic Alkyne Reactions
- Carbohydrate Chemistry and Synthesis
- Organophosphorus compounds synthesis
- Supramolecular Chemistry and Complexes
- Advanced Synthetic Organic Chemistry
- Cyclopropane Reaction Mechanisms
- Crystallography and molecular interactions
- Organoboron and organosilicon chemistry
- interferon and immune responses
- Phosphorus compounds and reactions
- Molecular Sensors and Ion Detection
- Nanomaterials for catalytic reactions
- N-Heterocyclic Carbenes in Organic and Inorganic Chemistry
- Advanced biosensing and bioanalysis techniques
National University of Singapore
2022-2024
Bristol-Myers Squibb (United States)
2016-2021
University of Chicago
2009-2015
Massachusetts Institute of Technology
2014
Texas A&M University
2007-2013
Michael's a square: An easily prepared squaramide catalyst that promotes the highly enantioselective Michael addition reaction of diphenyl phosphite to range nitroalkenes is described. This method leads chiral β-nitro phosphonates, which are precursors biologically active β-amino phosphonic acids.
Phosphorothioate nucleotides have emerged as powerful pharmacological substitutes of their native phosphodiester analogs with important translational applications in antisense oligonucleotide (ASO) therapeutics and cyclic dinucleotide (CDN) synthesis. Stereocontrolled installation this chiral motif has long been hampered by the systemic use phosphorus(III) [P(III)]-based reagent systems sole practical means assembly. A fundamentally different approach is described herein: invention a...
A general method for regioselective C3-benzylation of indoles has been developed. Various 3-substituted and benzyl methyl carbonates with different electronic properties react under mild conditions to afford a diverse range 3-benzylindolenine products in good yields.
The large volume of research studying hydrogenation catalysis might suggest that stereoselective alkenes is a solved problem, but we believe the most important parts asymmetric methodology remain unmastered. popular chiral catalysts, Rh- and Ir-diphosphine complexes, do not hydrogenate largest categories prochiral alkenes, hindered tri- tetra-substituted ones, at useful rates unless substrate has “classical” coordinating functional group (CFG), for example, amides or homoallylic alcohols, to...
A palladium-catalyzed asymmetric arylation of 9-aminofluorene-derived imines using a chiral dialkylbiaryl phosphine as the supporting ligand has been developed. This transformation allows for enantioselective access to diverse range α-branched benzylamines.
Spatial distancing of a substrate's reactive group and nonreactive catalyst-binding from its pro-stereogenic element presents substantial hurdles in asymmetric catalysis. In this context, we report desymmetrizing Suzuki–Miyaura reaction that establishes chirality at remote quaternary carbon. The anionic, chiral catalyst exerts stereocontrol through electrostatic steering substrates, even as the charged become increasingly distanced. This study demonstrates precise long-range is achievable by...
Einfach zugänglich ist der im Schema gezeigte Squaramidkatalysator, die hoch enantioselektive Michael-Addition von Diphenylphosphit an Nitroalkene vermittelt. Dieser Ansatz führt zu chiralen β-Nitrophosphonaten, Vorstufen für biologisch aktive β-Aminophosphonsäuren sind. Detailed facts of importance to specialist readers are published as "Supporting Information". Such documents peer-reviewed, but not copy-edited or typeset. They made available submitted by the authors. Please note: The...
Acidities of iridium hydride intermediates were shown to be critical in some transformations mediated by the chiral analogues Crabtree's catalyst, 1-3. To do this, several experiments undertaken investigate acidities hydrogenation mixtures formed using these iridium-oxazoline complexes. DFT calculations indicated that acidity difference for Ir-H hydrogenations astounding; from N-heterocyclic carbene catalyst 1 was calculated around seven pK(a) units less acidic than those P-based complexes 2...
A set of general methods for the palladium-catalyzed decarboxylative C3-allylation and C3-benzylation indoles, starting from corresponding N-alloc N-Cbz respectively, is reported. This chemistry provides ready access to a wide range functionalized indolenines in good excellent yields. tandem process, wherein palladium catalyzed allylation coupled with Mizoroki–Heck reaction, offers simple route cinnamylated products.
We report the intermolecular palladium-catalyzed reaction of tert-butyl propargyl carbonate with tryptamine derivatives or other indole-containing bis-nucleophiles. The proceeds under mild conditions and low catalyst loadings to afford novel spiroindolenine products in good high yields.
Synthetic application of asymmetric catalysis relies on strategic alignment bond construction to creation chirality a target molecule. Remote desymmetrization offers distinctive advantages spatial decoupling catalytic transformation and generation stereogenic element. However, such separation presents substantial difficulties for the chiral catalyst discriminate distant enantiotopic sites through reaction three or more bonds away from prochirality center. Here, we report strategy that...
Cavitands have emerged as privileged architectures in supramolecular chemistry. Nonetheless, achieving structural diversity and tunability through heterofunctionalization along the rims of macrocycles has remained a formidable challenge. As rudimental example, stepwise conversion C4v-symmetric scaffolds to inherently chiral ABCD patterns is synthetically impractical owing low theoretical yields (0.8%) need for chromatographic enantioseparation.Herein, we report catalytic desymmetrization...
Asymmetric hydrogenations of monoenes and dienes were performed to obtain terminal deoxypolyketide fragments A the corresponding internal chirons B C. The chiral N-heterocyclic carbene catalyst 1 was used throughout. Modest selectivities for simple relayed into high preparations in which either two or one an optically pure starting material used. Curiously, face hydrogenation alpha,beta-unsaturated esters consistently opposite those that had been observed styrene stilbene derivatives...
Reported here are methods for the direct construction of a range spirocyclized oxindoles and indolenines in good to excellent yields. Specifically, we report palladium-catalyzed reactions indoles, both functioning as bis-nucleophiles, with propargyl carbonates afford spirocyclic products having an exocyclic double bond on newly formed ring. The reaction proceeds through process wherein first nucleophilic unit oxindole or indole reacts allenyl-palladium species, from oxidative addition Pd(0)...
A strategy to prepare compounds with multiple chirality axes, which has led a concise total synthesis of compound 1A complete stereocontrol, is reported.
Abstract A carbene‐oxazoline catalyst 1 proved to be an effective for reduction of enol ether that the literature suggested could not hydrogenated effectively by P,N ‐Ir catalysts. Thus, a series ester and alcohol substrates were using . Good excellent enantioselectivities high conversions obtained.
ADVERTISEMENT RETURN TO ISSUEPREVLetterNEXTSynthesis of (S,R,R,S,R,S)-4,6,8,10,16,18- Hexamethyldocosane from Antitrogus parvulus via Diastereoselective HydrogenationsJianguang Zhou, Ye Zhu, and Kevin BurgessView Author Information Texas A & M University, Chemistry Department, P.O. Box 30012, College Station, 77842 Cite this: Org. Lett. 2007, 9, 7, 1391–1393Publication Date (Web):March 6, 2007Publication History Received5 February 2007Published online6 March inissue 1...
An iridium carbene oxazoline complex was used to catalyze hydrogenations of trisubstituted alkenes give terminal and internal 1,3-hydroxymethyl chirons. The products are accessible in all possible stereoisomeric forms. These do not require strongly coordinating functionalities on the substrate, some key cases, catalyst- rather than substrate-controlled stereoselectivities observed. It is hypothesized that these reactions would be feasible using or rhodium diphosphine complexes.
Harnessing radical intermediates in regioselective reactions presents a substantial challenge. Here, we report novel control strategy through engineering covalently tethered transition metal-photocatalysts that conjoin Pd-phosphine and Ru/Ir photoredox units. This allows us to override the innate regioselectivity of Pd-catalysed C-H allenylation N-aryl tetrahydroisoquinolines.
(-)-Spongidepsin 1, a cytotoxic marine natural product, was prepared via two iridium-catalyzed hydrogenation reactions; both were highly stereoselective, giving convenient access to pivotal intermediates. This synthesis modified give several spongidepsin analogues, and their cytotoxicities compared with those of the product.
A highly stereoselective synthesis of a cyclic dinucleotide (CDN) STING agonist containing two chiral thiophosphoramidate linkages is described. These rare yet key functional groups were, for the first time, installed efficiently and with high diastereoselectivity using specially designed P(V) reagent. By utilizing this strategy, CDN was prepared in greater than 16-fold higher yield prior P(III) approach, fewer hazardous reagents chromatographic purifications.