rate-determining C−C bond formation. The nucleophilic reactivities span over a range of 108 from the vinylethers 1a,x as the least reactivecompounds (comparable to allylsilanes) to the highly nucleophilic silyl ketene acetal 1u (comparable to enamines). Linear free enthalpy relationships are used to compare the reactivities of these compounds with those of other aliphatic and aromatic π-nucleophiles.
Electrogenerated Acid-Catalyzed Reactions of Acetals, Aldehydes, and Ketones with Organosilicon Compounds, Leading to Aldol Reactions, Allylations, Cyanations, and Hydride Additions
electrogenerated acid (EG acid) in the silicon-mediated acid-catalyzed reactions; e.g., aldol reactions, allylations, cyanations, and hydride additions is described. The aldol reaction of acetals 1 with enol trimethylsilyl ethers 3 and 1,2-bis(trimethylsiloxy)alkenes 4 gives the corresponding adducts 5 and 6, respectively. The reaction proceeds smoothly with EG acid derived from perchlorate salts such
“High-surface alkali metals” can be conveniently prepared via deposition of corresponding metals on various supports such as sodium chloride, polyethylene, polypropylene and cross-linked polystyrene from their solutions in liquid ammonia. Alkali metals deposited on polymeric supports can be stored in form of stable suspensions in inert solvents and used for the acyloin and Dieckmann condensations and
Towards High-Performance Lewis Acid Organocatalysis
作者:Lars Ratjen、Manuel van Gemmeren、Fabio Pesciaioli、Benjamin List
DOI:10.1002/anie.201402765
日期:2014.8.11
The combination of Lewisacidorganocatalysis and internal hydrogen‐bond assistance was used to develop a new type of highly active disulfonimide catalyst. The increased Lewis acidity was documented by activity comparisons as well as theoretical investigations. Finally, the potential of the hydrogen‐bond‐assisted disulfonimide catalyst was demonstrated by its application in an enantioselective transformation
Synthesis of 3-alkylcyclopentane-1,2-diones by acid-catalysed rearrangements of α-ketoglycol derivatives
作者:Gerarld Pattenden、Simon Teague
DOI:10.1016/s0040-4039(00)87117-8
日期:1982.1
Treatment of the adducts(3) derived from 1,2-bis(trimethylsilyloxy)cyclopenten and acetals, with p-toluene sulphonic acid in hot benzene is shown to lead to the corresponding 3-alkylcyclopentane-1,2-diones(4).