Action des dialkylcuprates de lithium sur les aldéhydes α,β -éthylénioues
作者:C. Chuit、J.P. Foulon、J.F. Normant
DOI:10.1016/0040-4020(80)80126-8
日期:1980.1
Nearly exclusive 1-4 addition produts obtained by action of lithium dialkylcuprates with α,β ethylenic aldehydes. Non polar solvents and low temperatures favour this reaction .Only α,β-ehylenic aldehydes having a trisubstituted double bond give a relatively important proportation of 1–2 addition product.
conditions. The reaction seems to progress through iron‐catalyzed self‐condensation of the benzyl TMS ether to the corresponding dibenzylic ether. The use of excess arene relative to benzyl TMS ether produced mono‐benzylated arene (di‐ and tri‐arylmethane products), whereas the use of excess benzyl TMS ether versus arene provided bis‐benzylated arene (polyarylated products) in high yields and regioselectivities
For the simultaneous preparation of molecules having both the nucleophilic and electrophilic sites, allyl trimethylsilyl ethers as eletrophilic allylating reagents are studied. Allyl trimethylsilyl ethers react with allyl trimethylsilanes in the pressence of a catalytic amount of ZnCl2 at room temperature to afford the corresponding 1,5-dienes in good yields.
A practical method for activation of commercial lithium hydride: reductive silylation of carbonyl compounds with lithium hydride and chlorotrimethylsilane
作者:Takeshi Ohkuma、Shohei Hashiguchi、Ryoji Noyori
DOI:10.1021/jo00080a035
日期:1994.1
Commercially available lithium hydride, an essentially inert metal hydride, can be activated as a hydride source by an equimolar amount of chlorotrimethylsilane and a catalytic amount of a Zn salt or Zn powder. Aromatic and aliphatic ketones, as well as nonenolizable aldehydes, are reductively converted to the trimethylsilyl ethers of the corresponding alcohols in high yields by treatment with this reagent system in dichloromethane or toluene at 28 to 40 degrees C for 25-50 h. This procedure has many advantages including the safety and low cost of the reagents and operational simplicity and provides a practical method for carbonyl reduction. X-ray induced Auger electron spectroscopy analysis suggests that a Zn(II)I species is the catalyst of the heterogeneous reaction.
Activation of Reducing Agents: Sodium Hydride-Containing Complex Reducing Agents; XVII<sup>1</sup>. A Very Efficient, One-Pot Reductive Silylation of Saturated or Unsaturated Ketones and Aldehydes