A practical procedure of low valent tin mediated Barbier allylation of aldehydes in wet solvent

Use of aluminium as the reducing metal in spontaneous bimetal redox reaction has been elegantly exploited for allylation/crotylation of aldehydes in wet solvent. Here, low valent tin was prepared in situ by reduction of SnCl₂·2H₂O with aluminium in THF/water. The resulting low valent tin acted as an efficient mediator for allylation and crotylation of aldehydes (3a–q) producing the corresponding homoallylic alcohols. The efficacy of this procedure was due to its operational simplicity, practical viability, inexpensiveness, good yields of the products and short reaction time.     

Tin mediated Barbier type allylation in ionic liquids

The Barbier type allylation of carbonyl compounds is a useful organic transformation as the resultant homoallylic alcohols are important building blocks for many biologically active molecules. Tin mediated Barbier allylation of different carbonyl compounds in room temperature ionic liquid, [BMIM][BF₄] afforded the corresponding homoallylic alcohols in good to excellent yields. The ionic liquid was successfully recycled and reused in allylation reactions.     

烯丙基溴和锡与醛的选择性加成反应

应用烯丙基溴和锡粉在少量水存在下和四氢呋喃中可使醛选择性烯丙基化,这一反应可用于那些同时含有对格氏试剂有反应活性的羟基、酚羟基、芳香族硝基和酮羰基等官能团的醛类以引入烯丙基生成相应的高烯丙基醇.     

Indium-catalyzed Barbier allylation reaction

Barbier allylation reaction of carbonyl compounds with allyl bromide was investigated using a catalytic amount of indium (0), indium (I) or indium (III) salts in the presence of a reducer and chlorotrimethylsilane (TMSCl). The Mn/TMSCl couple turned out to be the most efficient system to regenerate active indium in the allylation reaction of various carbonyl compounds including α- and β-oxygenated aldehydes.     

Barbier reaction in the regime of metal oxide: the first example of carbonyl allylation mediated by tetragonal tin(II) oxide

Facile synthesis of homoallylic alcohols is achieved from allyl halides and aldehydes or ketones over an all-oxide heterogenous media involving beta-SnO and catalytic Cu2O.     

Metallic bismuth mediated allylation of aldehydes to homoallylic alcohols

In the presence of metallic bismuth, allyl halides were found to react with aldehydes under mild conditions to give the corresponding homoallylic alcohols in good yields.     

Mild and efficient allylation of aldehydes mediated by titanium(III) chloride

A mild, chemoselective and efficient method for the allylation of aldehydes is described. Ketones remained unreacted under the reaction conditions.     

Facile synthesis of γ-alkenylbutenolides from Baylis-Hillman adducts: consecutive in-mediated Barbier allylation, PCC oxidation, isomerization, and Zn-mediated Barbier allylation

Alkenylbutenolides were synthesized regioselectively in good to moderate yields from Baylis-Hillman adducts via a consecutive indium-mediated Barbier type reaction between Baylis-Hillman bromide and aldehyde, PCC oxidation of the homoallylic alcohol, double bond isomerization, and zinc-mediated Barbier type alkenylation protocol.     

Efficient allylation of aldehydes promoted by carboxylic acids

A variety of carboxylic acids have been screened for mediating the allylation of aldehydes with allytributyltin in different solvents. A novel, general, and practical method of allylation of aldehydes promoted by carboxylic acids under mild reaction conditions has been developed. Among them, p-nitrobenzoic acid afforded high to quantitative yields of the homoallylic alcohol products, and can be easily recovered after workup by aqueous HCl. Glyoxylic acid self-catalyzed the allylation without adding any other promoter or catalyst to give the corresponding allylation product in good yield. The regioselectivity of the crotylation of aldehydes is tunable by controlling the acidity of the carboxylic acids. The crotylation of aldehydes produced the alpha-adduct as major products in moderate to good yields with CF(3)CO(2)H as a promoter. A possible mechanism for the allylation is also discussed.     

Efficient allylation of aldehydes with allyltributylstannane catalyzed by CuI

Cuprous iodide has been found to be a very effective catalyst for allylation of aldehydes with allyltributylstannane. The catalytic system efficiently promotes the allylation reaction in DMF to produce homoallylic alcohols in high yield.     

Enantioselective allylation of aldehydes promoted by chiral sulfur reagents

The addition of allylzinc bromide to aldehydes was studied with different chiral sulfur compounds acting as a catalyst. Yield differences and enantiomeric excesses were observed.     

Enantioselective allylation of aldehydes catalyzed by new bifunctional bisoxazoline-metal complexes

The asymmetric allylation reactions of aldehydes catalyzed by a 10 mol % bisoxazoline complex bearing a phosphine oxide moiety, which was newly designed and synthesized from l-serine, afforded the corresponding homoallylic alcohols in 48-74% yields with 39-86% ee. The reaction proceeds with the dual activation of the aldehyde and allylsilane by the Lewis acid and base of the catalyst. The evidence for the activation of the allylsilane was clarified by the ³¹P NMR spectra.     

Asymmetric allylation of aldehydes with allyltrichlorosilane promoted by chiral sulfoxides

Allylation of aldehydes with allyltrichlorosilane in the presence of sulfoxides is reported. The use of excess of (R)-methyl-p-tolylsulfoxide resulted in the formation of the corresponding homoallylic alcohols in good yields and moderate enantiomeric excesses.     

Rhenium complex-catalyzed allylation of aldehydes with allyltributylstannane

It was confirmed that the rhenium complex, ReBr(CO)₅, catalyzed the allylation of aldehydes with allyltributylstannane to give the corresponding homoallylic alcohols in moderate to good yields. Similarly, the reaction of aldehydes with enol silyl ether was efficiently promoted by the rhenium catalyst to afford the corresponding β-hydroxy carbonyl compounds.     

Highly diastereoselective reactions of (E)-cinnamyl chloride with aldehydes mediated by tin and aluminium

The reactions of (E)-cinnamyl chloride with aldehydes in H₂O: THF: HBr in the presence of tin and aluminium powders proceed with very high stereoselectivity.     

Samarium Barbier reactions of alpha-iodomethyloxazoles and thiazoles with aliphatic aldehydes

[reaction: see text] The reductive coupling of substituted alpha-iodomethyloxazoles and thiazoles with aliphatic aldehydes under Barbier conditions provides an effective method for the direct incorporation of intact heterocyclic systems.