A series of 5-hydroxypentenes was synthesized from the reaction mixture of Mg powder, 1,2-dibromoethane, 4-bromobutene and aldehydes in THF under ultrasound. This sonochemicalBarbierreaction provides a simple and alternative method for preparation of 5-hydroxypentene instead of the allylating reagent with epoxide.
A Stereoselective Approach to 2,6-Disubstituted Tetrahydropyrans by Conjugate Addition Reactions of Vinyl Sulfones
作者:D. Craig、G. Edwards、C. Muldoon
DOI:10.1055/s-1997-1016
日期:1997.11
A highly stereoselective synthesis of cis-2,6-disubstituted tetrahydropyrans from functionalised 5-hexen-1-ols has been developed. Free radical addition of para-toluenesulfonyl iodide to the hexenol and DBU-mediated elimination of HI from the intermediate β-iodosulfones gives vinyl sulfones: subsequent conjugate addition of the potassium alkoxide leads to a highly stereoselective (≥30:1) cyclisation.
Indium−Copper and Indium−Silver Mediated Barbier–Grignard-Type Alkylation Reaction of Aldehydes Using Unactivated Alkyl Halides in Water
作者:Zhi-Liang Shen、Yan-Lin Yeo、Teck-Peng Loh
DOI:10.1021/jo8000589
日期:2008.5.1
developed for the Barbier–Grignard-typealkylationreaction of aldehydes (including aliphatic version) usingunactivatedalkylhalides in water in the presence of an In/CuI/I2 or In/AgI/I2 system. The reactions proceeded more efficiently in water than in organic solvent. In, CuI or AgI, and I2 were all essential for the efficient progress of the reactions. A radical-type reaction mechanism was studied
在In / CuI / I 2或In / AgI / I 2系统存在下,使用未活化的烷基卤化物在水中进行醛的Barbier-Grignard型烷基化反应(包括脂肪族)的有效方法。该反应在水中比在有机溶剂中更有效地进行。In,CuI或AgI和I 2对反应的有效进行都是必不可少的。研究并提出了一种以4-戊烯为底物的自由基型反应机理。
Dibromomethane as one-carbon source in organic synthesis: a versatile methodology to prepare the cyclic and acyclic α-methylene or α-keto acid derivatives from the corresponding terminal alkenes
作者:Yung-Son Hon、Yu-Wei Liu、Cheng-Han Hsieh
DOI:10.1016/j.tet.2004.04.013
日期:2004.5
Ozonolysis of mono-substituted alkenes A-1 followed by reacting with a preheated mixture of CH2Br2–Et2NH affords α-substituted acroleins A-2 in good yields. Under very mild reaction conditions, these α-substituted acroleins A-2 can be easily converted to α-methylene esters A-4, which could be further converted to the corresponding α-keto esters A-5. This methodology can be also applied to the preparation
transfer, which eventually offers a new route to various α-amino ketones with excellent regioselectivity. The virtue of this transformation is that an unrefined isomeric mixture of alkenyl alcohols can be utilized as the readily available starting materials to lead to the regioconvergent amidation. Mechanistic investigations revealed that the reaction proceeds via a tandem process involving two key components