A Photoinduced Cobalt-Catalyzed Synthesis of Pyrroles through in Situ-Generated Acylazirines
摘要:
Tetrasubstituted pyrroles can be synthesized in a one-pot procedure from isoxazoles. The process includes the photoinduced in situ formation of acylazirines combined with a subsequent cobalt(II)-catalyzed ring expansion with 1,3-diketones.
Catalyst Control in Positional-Selective C–H Alkenylation of Isoxazoles and a Ruthenium-Mediated Assembly of Trisubstituted Pyrroles
作者:Pravin Kumar、Manmohan Kapur
DOI:10.1021/acs.orglett.9b00446
日期:2019.4.5
determining the positional selectivity in C–H alkenylation of isoxazoles. A cationic rhodium-mediated, strong-directing group promotes C(sp2)-H activation at the proximal aryl ring whereas, the palladium-mediated electrophilic metallation leads to the C(sp2)-H activation at the distal position of the directing group. Synthetic elaboration of this C–H alkenylation product via ruthenium and copper co-catalysis
Isoxazole group directed Rh(iii)-catalyzed alkynylation using TIPS-EBX
作者:Sukanya Das、Tanmoy Datta、Md. Abbasuddin Sk、Brindaban Roy、Raj K. Nandi
DOI:10.1039/d4ob00797b
日期:——
A highly effective isoxazole directed ortho C–H alkynylation has been developed. Rhodium(III) catalyzed direct di-(and/or mono) alkynylation using a hypervalent iodine reagent (TIPS-EBX) is reported. The reaction proceeds with a wide substrate scope under benign conditions. Preliminary mechanistic studies support this chelation assisted C–H alkynylation.
一种高效的异恶唑定向邻位C-H 炔基化反应已被开发出来。据报道,使用高价碘试剂 (TIPS-EBX) 进行铑 ( III ) 催化的直接二(和/或单)炔基化。该反应在良好的条件下以广泛的底物范围进行。初步机制研究支持这种螯合辅助的 C-H 炔基化。
Direct Synthesis of 4-Fluoroisoxazoles through Gold-Catalyzed Cascade Cyclization–Fluorination of 2-Alkynone <i>O</i>-Methyl Oximes
A tandem protocol for the synthesis of fluorinated isoxazoles has been developed via catalytic intramolecular cyclizations of 2-alkynone O-methyl mimes and ensuing fluorination. The reactions proceed smoothly at room temperature in the presence of 5 mol % of (IPr)AuCl, 5 mol % of AgOTs, 2.5 equiv of Selectfluor, and 2 equiv of NaHCO3. This process features an efficient one-pot cascade route to fluoroisoxazoles with high yields and high selectivity under mild reaction conditions.