75142-62-0Relevant articles and documents
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 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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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.
