Substrate Range of the Titanium TADDOLate Catalyzed Asymmetric Fluorination of Activated Carbonyl Compounds
作者:Andreas Bertogg、Lukas Hintermann、Dominique P. Huber、Mauro Perseghini、Maria Sanna、Antonio Togni
DOI:10.1002/hlca.201100375
日期:2012.3
4‐diazoniabicyclo[2.2.2]octane bis‐[tetrafluoroborate]) at room temperature. A series of α‐methylated β‐keto esters (3‐oxobutanoates, 3‐oxopentanoates) with bulky benzyl ester groups (60–90% ee) or phenyl ester (67–88% ee) have been fluorinated readily, whereas α‐acyl lactones were also readily fluorinated, but gave lower inductions (13–46% ee). Double stereochemical differentiation in β‐keto esters with chiral
Electrophilic α-Amination Reaction of β-Ketoesters Using <i>N</i>-Hydroxycarbamates: Merging Aerobic Oxidation and Lewis Acid Catalysis
作者:David Sandoval、Charles P. Frazier、Alejandro Bugarin、Javier Read de Alaniz
DOI:10.1021/ja310784f
日期:2012.11.21
The copper-catalyzed α-amination of carbonyl compounds using nitrosoformate intermediates as the electrophilic source of nitrogen is reported. The reaction mergesaerobicoxidation and Lewis acid catalysis. The scope of the reaction is broad in terms of both the N-substituted hydroxylamines and the β-ketoesters. The new methodology harnesses the power of nitrosoformate intermediates and demonstrates
The migration ability of hydrogen, the methyl, phenyl, p-methoxyphenyl, and p-nitrophenyl groups in the Wolff-rearrangement has been investigated with the aroyl-acyl-diazomethanes 1a-d. The results of the thermal and photochemical (direct and sensitized) reaction are discussed. The insertion of the intermediate aroyl-acylcarbenes 2 in the OH-bond of ethanol yielding 2-ethoxy-1,3-diketones 7 competes
endow the target compound with new and advantageous properties, yet this modification remains overlooked due to the absence of a general and practical synthetic methodology. Herein, we report the first general method to introduce the hexafluoroisobutyl group into ketoesters, malonates, 1,3-diketones, Schiff base esters and malononitrile. We demonstrated that the reaction occurs through an elimination/allylic
<i>tert</i>-Butyl Peroxybenzoate-Promoted α-Methylation of 1,3-Dicarbonyl Compounds
作者:Songjin Guo、Qian Wang、Yan Jiang、Jin-Tao Yu
DOI:10.1021/jo502204a
日期:2014.11.21
A tert-butyl peroxybenzoate (TBPB)-promoted direct a-methylation of 1,3-dicarbonyl compounds has been developed, providing alpha-methyl derivatives in moderate to good yields. In this procedure, TBPB plays a dual role, serving as both the methyl source and radical initiator. This work represents a key complement to the traditional alpha-methylation of 1,3-dicarbonyl compounds using methyl iodide.