A high temperature investigation using microwave synthesis for electronically and sterically disfavoured substrates of the Newman–Kwart rearrangement
作者:Jonathan D. Moseley、Philip Lenden
DOI:10.1016/j.tet.2007.02.101
日期:2007.5
Electronically deactivated and/or sterically hindered substrates undergo the Newman–Kwartrearrangement (NKR) at around 300 °C, beyond the range of most convenient and safe, small-scale laboratory equipment. We report here the convenient conversions of several difficult substrates using modern microwave technology, which has proven ideal for investigating this high temperature reaction in all but the most
Thiocarbamate-Directed Tandem Olefination–Intramolecular Sulfuration of Two <i>Ortho</i> C–H Bonds: Application to Synthesis of a COX-2 Inhibitor
作者:Wendong Li、Yingwei Zhao、Shaoyu Mai、Qiuling Song
DOI:10.1021/acs.orglett.8b00089
日期:2018.2.16
A palladium-catalyzed dual ortho C–H bond activation of aryl thiocarbamates is developed. This tandem reaction initiates by thiocarbamate-directed ortho C–H palladation, which leads to favorable olefin insertion rather than reductive elimination. The oxidative Heck reaction followed by another C–H activation and sulfuration affords the dual-functionalized products. This reaction provides a concise
We herein establish a multicomponent annulation method for the synthesis of valuable iminocoumarins using aryl thiocarbamates, internal alkynes, and sulfonamides as starting materials, which are safe and readily available. The key step is a Rh-catalyzed and sulfur-directed C—H bondactivation. Preliminary mechanistic investigations suggested that the nucleophilic attack of the sulfonamide on an active
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
Access to Coumarins by Rhodium-Catalyzed Oxidative Annulation of Aryl Thiocarbamates with Internal Alkynes
作者:Yingwei Zhao、Feng Han、Lei Yang、Chungu Xia
DOI:10.1021/acs.orglett.5b00364
日期:2015.3.20
A Rh-catalyzed annulation of aryl thiocarbamates with internal alkynes via C–H bond activation has been developed. This protocol provides a new route to 3,4-disubstituted coumarins.