75142-62-0Relevant academic research and scientific papers
Asymmetric radical cyclopropanation of dehydroaminocarboxylates: Stereoselective synthesis of cyclopropyl α-amino acids
Lee, Wan-Chen Cindy,Wang, Duo-Sheng,Zhang, Congzhe,Xie, Jingjing,Li, Bo,Zhang, X. Peter
, p. 1588 - 1601 (2021)
A catalytic radical process has been developed for asymmetric cyclopropanation of dehydroaminocarboxylates with in situ-generated α-aryldiazomethanes via Co(II)-based metalloradical catalysis (MRC). Through fine-tuning the environments of D2-symmetric chiral amidoporphyrin platform as the supporting ligands, the Co(II)-metalloradical system can effectively activate various α-aryldiazomethanes to cyclopropanate different dehydroaminocarboxylates under mild conditions, enabling the stereoselective synthesis of chiral cyclopropyl α-amino acid derivatives. In addition to high yields and excellent enantioselectivities, the Co(II)-catalyzed asymmetric radical cyclopropanation exhibits (Z)-diastereoselectivity, which is the opposite of uncatalyzed thermal reaction. Combined computational and experimental studies support a stepwise radical mechanism for the Co(II)-catalyzed cyclopropanation reaction. The resulting enantioenriched (Z)-α-amino-β-arylcyclopropanecarboxylates, as showcased for the efficient synthesis of dipeptides, may serve as unique non-proteinogenic amino acid building blocks for the design and preparation of novel peptides with restricted conformations.
Asymmetric Radical Process for General Synthesis of Chiral Heteroaryl Cyclopropanes
Deb, Arghya,Ke, Jing,Wang, Xiaoxu,Xu, Yijie,Zhang, X. Peter,Zhu, Yiling
supporting information, p. 11121 - 11129 (2021/08/03)
A highly efficient catalytic method has been developed for asymmetric radical cyclopropanation of alkenes with in situ-generated α-heteroaryldiazomethanes via Co(II)-based metalloradical catalysis (MRC). Through fine-tuning the cavity-like environments of newly-synthesized D2-symmetric chiral amidoporphyrins as the supporting ligand, the optimized Co(II)-based metalloradical system is broadly applicable to α-pyridyl and other α-heteroaryldiazomethanes for asymmetric cyclopropanation of wide-ranging alkenes, including several types of challenging substrates. This new catalytic methodology provides a general access to valuable chiral heteroaryl cyclopropanes in high yields with excellent both diastereoselectivities and enantioselectivities. Combined computational and experimental studies further support the underlying stepwise radical mechanism of the Co(II)-based olefin cyclopropanation involving α- and γ-metalloalkyl radicals as the key intermediates.
Asymmetric radical cyclopropanation of alkenes with in situ-generated donor-substituted diazo reagents via Co(II)-based metalloradical catalysis
Wang, Yong,Wen, Xin,Cui, Xin,Wojtas, Lukasz,Zhang, X. Peter
supporting information, p. 1049 - 1052 (2017/05/15)
Donor-substituted diazo reagents, generated in situ from sulfonyl hydrazones in the presence of base, can serve as suitable radical precursors for Co(II)-based metalloradical catalysis (MRC). The cobalt(II) complex of D2-symmetric chiral porphyrin [Co(3,5-DuBu-Xu(2'-Naph)Phyrin)] is an efficient metalloradical catalyst that is capable of activating different N-arylsulfonyl hydrazones for asymmetric radical cyclopropanation of a broad range of alkenes, affording the corresponding cyclopropanes in high yields with effective control of both diastereo- and enantioselectivity. This Co(II)-based metalloradical system represents the first catalytic protocol that can effectively utilize donor-type diazo reagents for asymmetric olefin cyclopropanation.
PROCESS FOR THE CYCLOADDITION OF A HETERO(ARYL) 1,3-DIPOLE COMPOUND WITH A (HETERO)CYCLOALKYNE
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Paragraph 0413, (2017/01/26)
A process is provided, comprising reacting a (hetero)aryl 1,3-dipole compound with a (hetero)cycloalkyne, wherein the (hetero)aryl 1,3-dipole compound comprises a 1,3-dipole functional group bonded to a (hetero)aryl group, and wherein the (hetero)aryl 1,3-dipole compound is a (hetero)aryl azide or a (hetero)aryl diazo compound; wherein: (i) the (hetero)aryl group of the (hetero)aryl 1,3-dipole compound comprises a substituent (ii) the (hetero)aryl group of the (hetero)aryl 1,3-dipole compound is an electron-poor (hetero)aryl group and wherein the (hetero)cycloalkyne is a (hetero)cyclooctyne or a (hetero)cyclononyne according to Formula (1). The invention also relates to the products obtainable by the process according to the invention.
PROCESS FOR THE CYCLOADDITION OF A HETERO(ARYL) 1,3-DIPOLE COMPOUND WITH A (HETERO)CYCLOALKYNE
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Page/Page column 106, (2015/08/06)
The present invention relates to a process comprising the step of reacting a (hetero)aryl 1,3-dipole compound with a (hetero)cycloalkyne, wherein: a (hetero)aryl 1,3-dipole compound is defined as a compound comprising a 1,3-dipole functional group, wherein the 1,3-dipole functional group is bonded to a (hetero)aryl group, and wherein the (hetero)aryl 1,3-dipole compound is a (hetero)aryl azide or a (hetero)aryl diazo compound; wherein: (i) the (hetero)aryl group of the (hetero)aryl 1,3-dipole compound comprises one or more substituents having a positive value for the para-Hammett substituent constant σp and/or the meta-Hammett substituent constant σm, and/or (ii) the (hetero)aryl group of the (hetero)aryl 1,3-dipole compound is an electron-poor (hetero)aryl group, wherein an electron-poor (hetero)aryl group is: (ii-a) a (hetero)aryl group wherein the (hetero)aromatic ring system is bearing a positive charge, and/or (ii-b) a (hetero)aryl group wherein the ratio {number of π-electrons present in the (hetero)aromatic ring system} : {number of protons present in the nuclei of the (hetero)aromatic ring system} is lower than 0.167 for a 6-membered ring, or lower than 0.200 for a 5-membered ring; and wherein the (hetero)cycloalkyne is a (hetero)cyclooctyne or a (hetero)cyclononyne according to Formula (1): The invention also relates to the products obtainable by the process according to the invention.
Alkylation of Aldehyde (Arenesulfonyl)hydrazones with Trialkylboranes
Kabalka, George W.,Maddox, John T.,Bogas, Ekaterini,Kelley, Shane W.
, p. 3688 - 3695 (2007/10/03)
(Arenesulfonyl)hydrazone derivatives of aryl aldehydes are readily alkylated by trialkylboranes in the presence of base to generate new organoboranes that may be converted to the corresponding substituted alkanes or alcohols depending upon the reaction conditions chosen. Both tosyl- and trisylhydrazone derivatives can be utilized in the reaction, which tolerates a variety of functional groups, making it a versatile alternative to both the Grignard and Suzuki-coupling reactions.
