5409-54-1Relevant academic research and scientific papers
Cp?Rh(III)/Bicyclic Olefin Cocatalyzed C-H Bond Amidation by Intramolecular Amide Transfer
Wang, Xiaoming,Gensch, Tobias,Lerchen, Andreas,Daniliuc, Constantin G.,Glorius, Frank
, p. 6506 - 6512 (2017/05/17)
A bicyclic olefin was discovered as a cocatalyst in a Cp?Rh(III)-catalyzed C-H bond amidation proceeding by an intramolecular amide transfer in N-phenoxyacetamide derivatives. Combining experimental and theoretical studies, we propose that the olefin promotes a Rh(III) intermediate to undergo oxidative addition into the O-N bond to form a Rh(V) nitrenoid species and subsequently direct the nitrenoid to add to the ortho position. The amide directing group plays a dual role as a cleavable coordinating moiety as well as an essential coupling partner for the C-H amidation. This methodology was successfully applied to the late-stage diversification of natural products and a marketed drug under mild conditions.
Regioselective syntheses of 2- and 4-formylpyrido[2,1-b]benzoxazoles
Li, Ke-Lai,Du, Zong-Bo,Guo, Can-Cheng,Chen, Qing-Yun
supporting information; experimental part, p. 3286 - 3292 (2009/09/08)
o-Acetaminophenols (2) reacted with Vilsmeier reagent under Meth-Cohn conditions to yield 2-formylpy-rido[2,l-6]benzoxazoles (5) unexpectedly besides the known compounds 2-(benzoxazol-2′-yl)-3-dimethylaminoacroleins (4). Refluxing 4 in acetic anhydride gave 4-formylpyrido[2,l-6]benzoxazoles (6), an isomer of 5. Both 5a and 6a were structurally characterized by X-ray crystallography. A mechanism for the formation of 5 involving sequential chlorination, dimerization, intramolecular elimination of HC1 to form the oxazole ring, formylation twice, and regioselective intramolecular nucleophilic cyclization to construct the pyridone ring is proposed.
