Potassium Fluoride on Alumina: Synthesis of O-Aryl N,N-Dimethylthiocarbamates and their Rearrangement into S-Aryl N,N-Dimethyl-Thiocarbamates Under Microwave Irradiation
摘要:
A series of O-aryl N,N-dimethyl thiocarbamates have been prepared by the reaction of dimethylthiocarbamoyl chloride with phenols absorbed on potassium fluoride on alumina. The rearrangement of O-aryl N,N-dimethylthiocarbamate into S-aryl N,N-dimethyl thiocarbamate under microwave irradiation was also studied. The use of conductive support like graphite or silicon carbide allow these rearrangements although the O-aryl N,N-dimethylthiocarbamates have very low dielectric lost.
作者:Thibault Gendron、Raul Pereira、Hafsa Y. Abdi、Timothy H. Witney、Erik Årstad
DOI:10.1021/acs.orglett.9b04280
日期:2020.1.3
Herein, we report that iron(II)/ammonium persulfate in aqueous acetonitrile mediates the Newman-Kwart rearrangement of O-aryl carbamothioates. Electron-rich substrates react rapidly under moderate heating to afford the rearranged products in excellent yields. The mild conditions, rapid reaction rates, and suitability for scale up offers immediate practical benefits to access functionalized thiophenols
Thiocarbamate‐Directed
<i>ortho</i>
C−H Bond Alkylation with Diazo Compounds
作者:Shengnan Jin、Zhan Chen、Yingwei Zhao
DOI:10.1002/adsc.201900804
日期:2019.10.22
We herein report a rhodium catalysed insertion of C(sp2)−H bond into diazo derived carbenes directed by a thiocarbamate group. This reaction provides a direct and efficient pathway to the ortho alkylation of phenol derivatives with a broad substrate scope. The C−H activation process is accomplished through a reversible electrophilic rhodation.
A convenient and selective synthesis of alkynylated coumarins from various aryl thiocarbamates and 1,3‐diynes or terminal alkynes via rhodium‐catalyzed C−H bond activation has been developed. In this transformation, both symmetrical and asymmetrical 1,3‐diynes could be applicable, obtaining various 3‐alkynylated coumarins in moderate to excellent yields. When the substituent is aryl group, the resulting
The Newman-Kwart Rearrangement of<i>O</i>-Aryl Thiocarbamates: Substantial Reduction in Reaction Temperatures through Palladium Catalysis
作者:Jeremy N. Harvey、Jesús Jover、Guy C. Lloyd-Jones、Jonathan D. Moseley、Paul Murray、Joseph S. Renny
DOI:10.1002/anie.200903908
日期:2009.9.28
Newman–Kwart rearrangement allows an escape from the harsh thermal conditions of the standard uncatalyzed reaction (see scheme). Mechanistic investigations, employing kinetic, isotopic labelling (2H, 18O, 34S) and DFT studies, suggest that the reaction proceeds through a five‐centred Pd–S coordinated oxidative addition, with intermolecular exchange of aryl and thiocarbamate moieties through dimerization of the