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16 results on '"Han, Chong"'

1. Highly Selective Palladium-Catalyzed Cross-Coupling of Secondary Alkylzinc Reagents with Heteroaryl Halides

Author

Yang, Yang, Niedermann, Katrin, Han, Chong, and Buchwald, Stephen L

Subjects
Inorganic Chemistry, Organic Chemistry, Chemical Sciences, Catalysis, Hydrocarbons, Halogenated, Indicators and Reagents, Ligands, Molecular Structure, Palladium, Phosphines, Chemical sciences
Abstract

The highly selective palladium-catalyzed Negishi coupling of secondary alkylzinc reagents with heteroaryl halides is described. The development of a series of biarylphosphine ligands has led to the identification of an improved catalyst for the coupling of electron-deficient heterocyclic substrates. Preparation and characterization of oxidative addition complex (L)(Ar)PdBr provided insight into the unique reactivity of catalysts based on CPhos-type ligands in facilitating challenging reductive elimination processes.

Published
2014

3. Stereocontrolled Synthesis of Arylomycin-Based Gram-Negative Antibiotic GDC-5338

Author

Wong, Nicholas, primary, Petronijević, Filip, additional, Hong, Allen Y., additional, Linghu, Xin, additional, Kelly, Sean M., additional, Hou, Haiyun, additional, Cravillion, Theresa, additional, Lim, Ngiap-Kie, additional, Robinson, Sarah J., additional, Han, Chong, additional, Molinaro, Carmela, additional, Sowell, C. Gregory, additional, and Gosselin, Francis, additional

Published
2019
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7. Asymmetric Synthesis of Akt Kinase Inhibitor Ipatasertib

Author

Han, Chong, primary, Savage, Scott, additional, Al-Sayah, Mohammad, additional, Yajima, Herbert, additional, Remarchuk, Travis, additional, Reents, Reinhard, additional, Wirz, Beat, additional, Iding, Hans, additional, Bachmann, Stephan, additional, Fantasia, Serena M., additional, Scalone, Michelangelo, additional, Hell, André, additional, Hidber, Pirmin, additional, and Gosselin, Francis, additional

Published
2017
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9. Synthesis of a Selective Estrogen Receptor Degrader via a Stereospecific Elimination Approach

Author

Lim, Ngiap-Kie, Cravillion, Theresa, Savage, Scott, McClory, Andrew, Han, Chong, Zhang, Haiming, DiPasquale, Antonio, and Gosselin, Francis

Abstract

An efficient synthesis of a selective estrogen receptor degrader, GDC-0810, bearing a challenging stereodefined (E)-tetrasubstituted all-carbon olefin core, is reported. The described synthetic route involves a highly diastereoselective addition of an arylmagnesium reagent 3ato ketone 4, yielding the key tertiary alcohol 2ain >99:1 dr. The corresponding tert-butyl carbonate derivative was identified among other leaving groups to provide the desired olefin geometry in a 98:2 E/Zratio via a concerted elimination. A four-step telescoped process was then developed starting from the tertiary alcohol 2ato produce GDC-0810 API as a pyrrolidine salt in 70% yield.

Published
2024
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10. Asymmetric Synthesis of Akt Kinase Inhibitor Ipatasertib

Author

Han, Chong, Savage, Scott, Al-Sayah, Mohammad, Yajima, Herbert, Remarchuk, Travis, Reents, Reinhard, Wirz, Beat, Iding, Hans, Bachmann, Stephan, Fantasia, Serena M., Scalone, Michelangelo, Hell, André, Hidber, Pirmin, and Gosselin, Francis

Abstract

A highly efficient asymmetric synthesis of the Akt kinase inhibitor ipatasertib (1) is reported. The bicyclic pyrimidine 2starting material was prepared via a nitrilase biocatalytic resolution, halogen–metal exchange/anionic cyclization, and a highly diastereoselective biocatalytic ketone reduction as key steps. The route also features a halide activated, Ru-catalyzed asymmetric hydrogenation of a vinylogous carbamic acid to produce α-aryl-β-amino acid 3in high yield and enantioselectivity. The API was assembled in a convergent manner through a late-stage amidation/deprotection/monohydrochloride salt formation sequence.

Published
2024
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15. Reaction discovery employing macrocycles: transannular cyclizations of macrocyclic bis-lactams.

Author

Han C, Rangarajan S, Voukides AC, Beeler AB, Johnson R, and Porco JA Jr

Subjects
Cyclization, Kinetics, Models, Molecular, Molecular Conformation, Stereoisomerism, Lactams chemistry, Macrocyclic Compounds chemistry
Abstract

Macrocyclic bis-lactams have been synthesized by cyclodimerization of homoallylic amino esters employing a Zr(IV)-catalyzed ester-amide exchange protocol. Base-mediated transannular cyclizations have been identified to access both bicyclic [5-11] and tricyclic [5-8-5] frameworks in good yield and diastereoselectivity. Preliminary mechanistic studies support an olefin isomerization-intramolecular conjugate addition pathway.

Published
2009
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16. Synthesis of carbamates and ureas using Zr(IV)-catalyzed exchange processes.

Author

Han C and Porco JA Jr

Subjects
Amines chemistry, Carbamates chemistry, Carbonates chemistry, Catalysis, Molecular Structure, Urea chemistry, Carbamates chemical synthesis, Urea chemical synthesis, Zirconium chemistry
Abstract

[reaction: see text] Zirconium(IV)-catalyzed exchange processes have been developed to prepare both carbamates and ureas from dialkyl carbonates and carbamates employing 2-hydroxypyridine (HYP) and 4-methyl-2-hydroxyquinoline (MeHYQ) as catalytic additives, respectively. A microwave acceleration effect was observed in Zr(IV)-catalyzed carbamate-urea exchange.

Published
2007
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