Article
Chemistry, Multidisciplinary
Teng Yuan, Kelton Radefeld, Chuan Shan, Carter Wegner, Erin Nichols, Xiaohan Ye, Qi Tang, Lukasz Wojtas, Xiaodong Shi
Summary: Here, we have reported an intermolecular asymmetric hydrative aldol reaction by using a vinyl-gold intermediate under ambient conditions. This reaction provides a base-free approach to β-hydroxy amides with high efficiency, yielding up to 95% and with over 50 examples. The use of vinyl gold intermediate as a reactive nucleophile and Fe(acac)(3) as a critical co-catalyst prevents undesired protodeauration, allowing the transformation to proceed under mild conditions with excellent functional group tolerance and stereoselectivity (>20:1 d.r. and up to 99% ee).
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Multidisciplinary
Minghui Zhu, Peixin Wang, Qinglong Zhang, Wenjun Tang, Weiwei Zi
Summary: The aldol reaction is an important and versatile transformation in organic synthesis, but achieving stereoselectivity for the formation of diastereomeric products is challenging. In this study, a new catalytic system was developed to overcome the selectivity limitations of the reaction. Computational studies provided insights into the reaction mechanism and stereochemistry of the catalytic system.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Multidisciplinary
Stuart C. D. Kennington, Saul F. Teloxa, Miguel Mellado-Hidalgo, Oriol Galeote, Sabrina Puddu, Marina Bellido, Pedro Romea, Felix Urpi, Gabriel Aullon, Merce Font-Bardia
Summary: A direct and asymmetric aldol reaction of N-acyl thiazinanethiones with aromatic aldehydes catalyzed by chiral nickel(II) complexes was reported. The reaction gives high yields of O-TIPS-protected anti-aldol adducts with remarkable stereocontrol and atom economy. The removal of the achiral scaffold provides enantiomerically pure intermediates with synthetic interest for producing anti-alpha-amino-beta-hydroxy and alpha,beta-dihydroxy carboxylic derivatives, with theoretical calculations explaining the observed high stereocontrol.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Multidisciplinary
Yulin Han, Anni Qin, Qian Zhang, Xue Zhang, Hui Qian, Shengming Ma
Summary: The Rh-catalyzed reaction allows for the efficient synthesis of cis-fused bicyclic products with excellent selectivity and tolerance towards synthetically useful functional groups. The proposed mechanism involves the rapid racemization of the allene moiety in the starting materials.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Multidisciplinary
Hitomi Tsuno, Jingfeng Shen, Hiroki Komatsu, Norihito Arichi, Shinsuke Inuki, Hiroaki Ohno
Summary: A gold-catalyzed cascade cyclization of naphthalene-tethered allenynes leads to strained fused phenanthrene derivatives. The reaction involves the nucleophilic reaction of an alkyne with an activated allene to generate a vinyl cation intermediate, followed by arylation with a tethered naphthalene ring to form the 4H-cyclopenta[def]phenanthrene (CPP) scaffold. The gold-catalyzed reaction of aryl-substituted substrates on the alkyne terminus also produces dibenzofluorene derivatives alongside the CPP derivatives, depending on the reaction conditions.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Organic
Bai Shi, Fangyi Jin, Qi Lv, Xinrong Zhou, Zhixiao Liao, Chenxia Yu, Kai Zhang, Changsheng Yao
Summary: A N-heterocyclic carbene (NHC) catalyzed formal [3 + 3] annulation reaction between & delta;-acetoxy allenoates and 1C,3O-bisnucleophiles has been developed for the synthesis of highly functionalized 4H-(fused)pyrans, with a broad substrate scope (30 examples, up to 77% yield).
ORGANIC & BIOMOLECULAR CHEMISTRY
(2023)
Article
Nanoscience & Nanotechnology
Miguel Sanchez-Fuente, Alberto Lopez-Magano, Alicia Moya, Ruben Mas-Balleste
Summary: Condensation of BINAPO-(PhCHO)(2) and 1,3,5-tris(4-aminophenyl)benzene(TAPB) leads to a new imine-based chiral organic material (COM) that can be post-functionalized through reductive transformation of imine linkers to amines. Although the imine-based material is not stable enough to be used as a heterogeneous catalyst, the reduced amine-linked framework can be efficiently utilized in asymmetric allylation of various aromatic aldehydes. The obtained yields and enantiomeric excesses are comparable to those observed for the molecular BINAP oxide catalyst, with the added advantage of recyclability offered by the amine-based material.
ACS APPLIED MATERIALS & INTERFACES
(2023)
Article
Chemistry, Organic
Isaac G. Sonsona, Andrea Vicenzi, Marco Guidotti, Giorgiana Denisa Bisag, Mariafrancesca Fochi, Raquel P. Herrera, Luca Bernardi
Summary: The study demonstrates the improved selectivity of an asymmetric aldol reaction by replacing part of the catalyst, and identifies the most suitable reaction conditions. However, these conditions seem to be limited to oxindoles bearing a 3-substituent of funapide.
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
(2022)
Article
Chemistry, Organic
Shabbir Ahmed Khan, A. Sanjeeva Kumar, K. C. Kumara Swamy
Summary: DBU-catalyzed spiro-annulation and ring expansion/dominoreaction of delta-acetoxy allenoates with cycl-2-ene-N-sulfonyl hydrazides led to ring-expanded products. On the other hand, cycl-3-ene/ane-N-sulfonyl hydrazones under similar conditions gave pyrazolecores. The key intermediates of spirocyclic and dienyl-amine were isolated and characterized. An extension to (R)-(-)-carvone-derived sulfonyl hydrazide also resulted in ring expansion and formation of pyrazoloazepine.
Article
Chemistry, Physical
Liangliang Zhang, Martin Oestreich
Summary: The passage describes a reaction sequence involving enantioselective copper-catalyzed conjugate silylation and diastereotopic group-selective aldol cyclization. The intramolecular aldol reaction's diastereoselectivity depends on the silicon nucleophile used, and the more basic zinc reagent enables thermodynamically driven cis-to-trans isomerization. A wide range of electron-withdrawing groups, including electron-deficient heterocycles, are compatible with the different procedures developed.
Article
Chemistry, Multidisciplinary
Suchen Zou, Bangkui Yu, Hanmin Huang
Summary: An efficient strategy for preventing beta-hydride elimination of alkylpalladium species by ligating palladium with adjacent amino group was developed, enabling a novel palladium-catalyzed ring-closing aminoalkylative amination of unactivated aminoenynes. The reaction is applicable to aminals and aliphatic aldehydes with secondary amines, providing straightforward access to structurally diverse exocyclic allenic amines with 5 to 12-membered N-heterocycles. A chiral phosphoramidite-ligated palladium complex was used as the catalyst to achieve an enantioselective variant with up to 93% ee. Synthetic transformations of the chiral products also resulted in structurally unique spirodiamines, including one pharmaceutically active molecule, through axial-to-central chirality transfer.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Multidisciplinary
Saul F. Teloxa, Miguel Mellado-Hidalgo, Stuart C. D. Kennington, Pedro Romea, Felix Urpi, Gabriel Aullon, Merce Font-Bardia
Summary: A direct and asymmetric aldol reaction between N-azidoacetyl-1,3-thiazolidine-2-thione and aromatic aldehydes catalyzed by a chiral nickel(II)-Tol-BINAP complex has been developed. The reaction gives anti alpha-azido-beta-silyloxy adducts with excellent stereocontrol and high yields. The removal of thiazolidinethione allows for the synthesis of a wide array of enantiomerically pure derivatives, providing a new route to di- and tripeptide blocks containing a beta-aryl-beta-hydroxy-alpha-amino acid.
CHEMISTRY-A EUROPEAN JOURNAL
(2022)
Article
Chemistry, Multidisciplinary
Eleonora Grandi, Michele Crotti, Marie-Catherine Sigmund, Guangcai Xu, Pieter G. G. Tepper, Gerrit J. J. Poelarends
Summary: Multi-enzymatic cascades using engineered enzymes are a useful tool for synthesizing complex molecules from simple starting materials. In this study, we engineered the enzyme 4-oxalocrotonate tautomerase (4-OT) to have increased aldolase activity. We then used the evolved 4-OT variant in a one-pot two-step cascade to synthesize enantioenriched epoxides from biomass-derived materials with high yields and enantioselectivity. We also developed a three-step enzymatic cascade for the production of chiral aromatic triols with high enantiopurity and good isolated yields.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Applied
Satoshi Sakai, Akane Fujioka, Koji Imai, Kei Uchiyama, Yohei Shimizu, Kosuke Higashida, Masaya Sawamura
Summary: The silver-catalyzed asymmetric aldol reaction of isocyanoacetic acid derivatives with aldehydes has been developed using a chiral prolinol-phosphine ligand as a hydrogen-bond-donating P,N,O ligand. DFT calculations revealed a stepwise reaction mechanism, involving C-C bond formation and subsequent enantioselectivity-determining ring formation. The prolinol moiety of the ligand activates the aldehyde through a two-point hydrogen bond, facilitating the stereocontrolled cyclization. Additional nonclassical hydrogen bonds and London dispersion interactions may also contribute to stereocontrol.
ADVANCED SYNTHESIS & CATALYSIS
(2022)
Article
Chemistry, Multidisciplinary
Xing Yang, Pankaj Kumar Majhi, Huifang Chai, Bin Liu, Jun Sun, Ting Liu, Yonggui Liu, Liejin Zhou, Jun Xu, Jiawei Liu, Dongdong Wang, Yanli Zhao, Zhichao Jin, Yonggui Robin Chi
Summary: This research introduces a novel catalytic strategy to modulate the thermodynamics and control the enantioselectivities of asymmetric aldol reactions via post-aldol processes. By using an NHC catalyst to activate a masked enolate substrate, the study successfully achieves enantioselective acylative kinetic resolution, resulting in acylated aldol products with high optical purities.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
