Umpolung Difunctionalization of Carbonyls via Visible-Light Photoredox Catalytic Radical-Carbanion Relay
作者:Shun Wang、Bei-Yi Cheng、Matea Sršen、Burkhard König
DOI:10.1021/jacs.0c00629
日期:2020.4.22
catalysis with the Wolff–Kishner (WK) reaction allows the difunctionalization of carbonyl groups by a radical-carbanion relay sequence (photo-Wolff–Kishner reaction). Photoredox initiated radical addition to N-sulfonylhydrazones yields α-functionalized carbanions following the WK-type mechanism. With sulfur-centered radicals, the carbanions are further functionalized by reaction with electrophiles
poses considerable challenges. Herein we report a Pd-catalyzed enantioselective three-component coupling of N-tosylhydrazone, arylhalide, and terminalalkyneunder mild conditions utilizing a novel chiral sulfinamide phosphine ligand (GF-Phos), which provides a facile access to chiral diarylmethyl alkynes, which are useful synthons in organic synthesis as well as exist as the skeleton in many bioactive
Pd(0)-Catalyzed Tandem One-Pot Reaction of Biphenyl Ketones/Aldehydes to the Corresponding Di-substituted Aryl Olefins
作者:Yang Liu、Ping Liu、Yan Liu、Yu Wei
DOI:10.1002/cjoc.201600870
日期:2017.7
Synthesis of di‐substituted aryl olefins via a Pd(0)‐catalyzed cross‐coupling reaction of biphenyl ketones/aldehydes, tosylhydrazide, and aryl bromides (or benzyl halides) was developed. This methodology was achieved by one‐pot two‐step reactions involving the preparation of N‐tosylhydrazones by reacting tosylhydrazide with biphenyl ketones/aldehydes, followed by coupling with aryl bromides (or benzyl
Direct Synthesis of Propen-2-yl Sulfones through Cascade Reactions Using Calcium Carbide as an Alkyne Source
作者:Lei Gao、Zhenrong Liu、Xiaolong Ma、Zheng Li
DOI:10.1021/acs.orglett.0c01915
日期:2020.7.2
A simple method for the construction of propen-2-yl sulfones through cascadereactions of calcium carbide with arylsulfonylhydrazones using copper as a mediator is described. The salient features of this protocol are the use of readily available and easy-to-handle alkyne source, broad substrate scope, open-air condition, and simple operation procedure.
Ultrafast Study of <i>p</i>-Biphenylyldiazomethane and <i>p</i>-Biphenylylcarbene
作者:Jin Wang、Gotard Burdzinski、Terry L. Gustafson、Matthew S. Platz
DOI:10.1021/jo061029+
日期:2006.8.1
p-Biphenylyldiazomethane was excited by femtosecond pulses of UV light in acetonitrile, in cyclohexane, and in methanol. Ultrafast photolysis produces a singlet excited state of p-biphenylyldiazomethane with λmax = 490 nm, and lifetimes of less than 300 fs in acetonitrile, in cyclohexane, and in methanol. The decay of the excited state is accompanied by the growth of transient absorption with λmax