Direct C–H α-Arylation of Enones with ArI(O<sub>2</sub>CR)<sub>2</sub> Reagents
作者:Felipe Cesar Sousa e Silva、Nguyen T. Van、Sarah E. Wengryniuk
DOI:10.1021/jacs.9b11282
日期:2020.1.8
mediated by hypervalent iodine reagents. The reaction proceeds via a reductive iodonium Claisen rearrangement of in situ β-pyridinium silyl enol ethers. The aryl groups are derived from ArI(O2CCF3)2 reagents, which are readily accessed from the parent iodoarenes. It is tolerant of a wide range of substitution patterns and the incorporated arenes maintain the valuable iodine functional handle. Mechanistic
An Efficient Approach to <i>Aspidosperma </i>Alkaloids via [4 + 2] Cycloadditions of Aminosiloxydienes: Stereocontrolled Total Synthesis of (±)-Tabersonine. Gram-Scale Catalytic Asymmetric Syntheses of (+)-Tabersonine and (+)-16-Methoxytabersonine. Asymmetric Syntheses of (+)-Aspidospermidine and (−)-Quebrachamine
作者:Sergey A. Kozmin、Tetsuo Iwama、Yong Huang、Viresh H. Rawal
DOI:10.1021/ja017863s
日期:2002.5.1
readily adapted to the asymmetric synthesis of these compounds. The strategy is demonstrated by the total synthesis of (+/-)-tabersonine (rac-1), proceeding through a 12-step sequence. The basis for this approach was provided by a highly regio- and stereoselective [4 + 2] cycloaddition of 2-ethylacrolein with 1-amino-3-siloxydiene developed in our laboratory. Subsequent elaboration of the initial adduct
What′s your poison? An expedient total synthesis of strychnine has been accomplished through a newly developed reaction sequence involving a catalytic asymmetric counteranion-directed vinylogous 1,4-addition, a silyl enol ether quaternary arylation, and an intramolecular Heck reaction.
A General Strategy to <i>Aspidosperma</i> Alkaloids: Efficient, Stereocontrolled Synthesis of Tabersonine
作者:Sergey A. Kozmin、Viresh H. Rawal
DOI:10.1021/ja983198k
日期:1998.12.1
Regiocontrolled Synthesis of Carbocycle-Fused Indoles via Arylation of Silyl Enol Ethers with <i>o</i>-Nitrophenylphenyliodonium Fluoride
作者:Tetsuo Iwama、Vladimir B. Birman、Sergey A. Kozmin、Viresh H. Rawal
DOI:10.1021/ol990759j
日期:1999.8.1
[formula: see text] A new, regiocontrolledsynthesis of carbocycle-fused indoles has been developed. The two-step procedure involves first the regiospecific arylation of silyl enol ethers with o-nitrophenylphenyliodonium fluoride (1). Reduction of the nitro group on the aromatic ring with TiCl3 followed by spontaneous condensation of the aniline with the ketone then affords the indole products.