Results 81 to 90 of about 187,468 (290)

Base-free enantioselective SN2 alkylation of 2-oxindoles via bifunctional phase-transfer catalysis

Beilstein Journal of Organic Chemistry, 2021
N-Protected oxindole derivatives of unprecedented malleability bearing ester moieties at C-3 have been shown to participate in enantioselective phase-transfer-catalysed alkylations promoted by ad-hoc designed quaternary ammonium salts derived from ...
Mili Litvajova, Emiliano Sorrentino, Brendan Twamley, Stephen J. Connon   +3 more
doaj   +1 more source

Cinchona Alkaloid-Catalyzed Asymmetric Conjugate Additions: The Bifunctional Brønsted Acid-Hydrogen Bonding Model. [PDF]

, 2016
Wynberg's report from 1977 that natural cinchona alkaloids catalyze the asymmetric conjugate addition of aromatic thiols to cycloalkenones is a landmark discovery in hydrogen bonding organocatalysis.
Grayson, Matthew N, Houk, KN
core   +3 more sources

Catalytic Strategies for Amide‐Based Michael Additions: Advances and Perspectives

Journal of Chemistry, Volume 2026, Issue 1, 2026.
The Michael addition is a cornerstone transformation in organic synthesis, enabling efficient C–C and C–heteroatom bond formation. Traditionally, α,β‐unsaturated carbonyl compounds such as enones and esters have dominated as Michael acceptors, whereas α,β‐unsaturated amides remain underutilized due to their strong resonance stabilization and low ...
Muhammad Naufal, Elvira Hermawati, Ace Tatang Hidayat, Dadan Sumiarsa, Ika Wiani Hidayat, Jamaludin Al-Anshori, Tulika Banerjee   +6 more
wiley   +1 more source

SYNTHESIS OF THREE NEW BIFUNCTIONAL GLUCOSE-THIOUREA ORGANOCATALYSTS AND THEIR APPLICATION IN ASYMMETRIC MICHAEL ADDITION

Studia Universitatis Babes-Bolyai Chemia, 2017
Three new glucose-based asymmetric bifunctional organocatalysts containing a 6-aminopyridyl or a 6-methylpyridyl or a cinchona unit were synthesized. Asymmetric Michael addition of pentane-2,4-dione to β-nitrostyrene was catalyzed successfully by these ...
Sándor NAGY, Petra KOZMA, Péter KISSZÉKELYI, Dóra BEZZEGH, Péter HUSZTHY, József KUPAI   +5 more
doaj   +1 more source

Opportunities When Chemistry Meets Biology in Catalysis and Synthesis

Transformative Chemistry, Volume 1, Issue 1, December 2025.
Biosynthesis and chemical synthesis possess complementary strengths and limitations. Integrating these two systems across multiple levels offers opportunities for molecular synthesis to become highly efficient, precise, versatile, and scalable in the future, while also ensuring environmental compatibility and resource renewability.
Xiao Xiao, Xinyi Ren, Baoguo Zhao, Xiaoguang Lei, Wen Liu, Kuiling Ding   +5 more
wiley   +1 more source

Optimization of Subcritical Water Extraction Process for Polyphenols from Cinchona calisaya and Their Activity Analysis

Molecules
This study expands research on Cinchona calisaya, which has traditionally focused on alkaloids, to address the insufficient comprehensive utilization of its resources.
Guangxin Li, Yujie Zhou, Dong Xie, Jingwen Zhang, Zhengshan Hu, Yuanping He, Lihua Zou, Ping Zhao, Yingjun Zhang, Xiaoqin Yang, Sengkew Wee   +10 more
doaj   +1 more source

Multispecies Solidarity: How People and Cinchona Survived the COVID‐19 Pandemic in Loja, Ecuador

Culture, Agriculture, Food and Environment, Volume 47, Issue 2, December 2025.
ABSTRACT This article uses the case of Cinchona officinalis entrepreneurship during the COVID‐19 pandemic to explore how dynamics of care and extraction figure within the construct of multispecies solidarity. C. officinalis is an endangered medicinal tree that holds global historical significance as a natural source of quinine.
Katharine McNamara
wiley   +1 more source

Strategies for the synthesis of enantiopure compounds focused on organocatalysis [PDF]

, 2012
Podeu consultar el llibre complet a: http://hdl.handle.net/2445/32393The preparation of enantiomerically pure compounds (EPC) is a continuous social demand due to the clinical advantages that enantiopure drugs offer over the racemic forms. Here, the best
Arróniz, Carlos, Escolano Mirón, Carmen   +1 more
core  

Enantioselective alkylation of β-keto esters promoted by dimeric Cinchona-derived ammonium salts as recoverable organocatalysts [PDF]

, 2011
Dimeric anthracenyldimethyl-derived Cinchona ammonium salts are used as chiral organocatalysts in 5 mol% for the phase-transfer enantioselective alkylation reaction of 2-alkoxycarbonyl-1-indanones with activated bromides.
Chinchilla, Rafael, Nájera, Carmen, Tarí Segarra, Silvia, Yus, Miguel   +3 more
core   +2 more sources

Antiparasitic hybrids of Cinchona alkaloids and bile acids.

European journal of medicinal chemistry, 2013
A series of 16 hybrids of Cinchona alkaloids and bile acids (4a-h, 5a-h) was prepared by means of a Barton-Zard decarboxylation reaction. Quinine, quinidine, cinchonine and cinchonidine were functionalized at position C-2 of the quinoline nucleus by ...
A. Leverrier, J. Bero, M. Frédérich, J. Quetin-Leclercq, J. Palermo   +4 more
semanticscholar   +1 more source