221385-63-3Relevant academic research and scientific papers
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.
