Chemoselective Allylation Research Articles

Chemoselective allylation of aldehydes using cerium(III) chloride: simple synthesis of homoallylic alcohols

Aldehydes undergo smooth nucleophilic addition with allyltributylstannane in the presence of CeCl 3·7H 2O in acetonitrile under extremely mild reaction conditions to afford the corresponding homoallylic alcohols in excellent yields with high chemoselectivity. This method is very useful especially for the allylation of aldehydes bearing acid sensitive functionalities such as TBDMS, THP ethers, acetonides, aryl alkyl ethers and carbamates.

Synthesis of Homoallyl Ethers via Allylation of Acetals in Ionic Liquids Catalyzed by Trimethylsilyl Trifluoromethanesulfonate.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Synthesis of homoallyl ethers via allylation of acetals in ionic liquids catalyzed by trimethylsilyl trifluoromethanesulfonate.

The chemoselective allylation of acetals using allyltrimethylsilane in ionic liquids is catalyzed by TMS triflate (5.0-20.0 mol %). The reaction proceeds smoothly at room temperature to afford the corresponding homoallyl ether in good yield. Since the ionic liquids are easily recovered and recycled, they are a useful alternative to dichloromethane, which is the commonly used solvent for allylations. [reaction--see text]

Chemo-, regio-, and enantioselective Pd-catalyzed allylic alkylation of indolocarbazole pro-aglycons.

[reaction: see text] Monosubstituted isomerically pure indolopyrrolocarbazole precursors have been prepared via palladium-catalyzed asymmetric allylic alkylation methodology, employing both achiral cyclopentenyl electrophiles and chiral glycal derivatives. Chemoselective allylation of (bis)indole lactam pro-aglycon 3 allows access to N-distally substituted indolopyrrolocarbazole derivatives; glyoxamide precursor 14 provides entry into N-proximally substituted derivatives.

Indium mediated allylation and propargylation reactions of dimethyl acetals and ketals

Indium mediated allylation and propargylation reactions of acetals and ketals with various allyl or propargyl bromides in aqueous media successfully provided the corresponding homoallylic or homopropargylic (and allenylic) alcohol, respectively, in moderate to good yields. Highly chemoselective allylation is also described. The ketal and aryl acetal could be selectively allylated over the aliphatic one in 80–84% yields.

Chelation control through the coordination of an olefinic π-bond to Lewis acid

The reaction of a 1:1 mixture of ortho-alkenylbenzaldehydes 3 and their para-isomers 4 with Bu 3SnH (1 equiv.) in the presence of Me 3Al (1 equiv.) resulted in very high (>10:1) to good (3.4:1) chemoselective reduction of 3, giving the ortho-alkenyl benzyl alcohol 5 selectively. Similarly, the highly chemoselective allylation of 3d in the presence of 4d was observed when the mixture was treated with allyltributyltin/Me 3Al. The chemoselectivities are most probably due to the bidentate chelation of the Lewis acid to an olefinic π-bond and a lone pair of aldehydes.

Scandium trifluoromethanesulfonate-catalyzed chemoselective allylation reactions of carbonyl compounds with tetraallylgermane in aqueous media

Scandium(III) triflate-catalyzed allylation of carbonyl compounds with tetraalylgermane proceeded readily in aqueous nitromethane to afford homoallyl alcohols in excellent to good yields. The presence of H 2O is indispensable for the allylation of aldehydes to proceed smoothly. Aldehydes were allylated highly chemoselectively in the presence of ketone moieties.

Chemoselective allylation of aldimine with allyltriethylgermane by the combined use of BF3•OEt2 and AcOH

Allyltriethylgermane reacts with aldimines in preference to aldehydes by means of BF3•OEt2 and AcOH to afford homoallylic amines in high yields; three component syntheses of homoallytic amines starting from aldehyde, aniline and allylgermane were successfully achieved.

π‐アリルパラジウム錯体を用いる有機合成のルネッサンス

π-Allylpalladium complexes have an electrophilic character and have been widely utilized for the catalytic C-C bond formation reaction with various nucleophiles in Organic Synthesis. We found that the reaction of allylic stannanes with aldehydes proceeded in the presence of palladium catalysts. Detailed investigation revealed that bis-π-allylpalladium complexes, which are a key intermediate in this reaction, have a nucleophilic character. This review describes the unprecedented reactions of the bis-π-allylpalladium complexes : (1) Catalytic allylation of aldehydes and imine. (2) Chemoselective allylation of imines in the presence of aldehydes. (3) Catalytic asymmetric allylation of imines. (4) Catalytic amphiphilic allylation.

Manganese-Mediated Reactions in Aqueous Media: Chemoselective Allylation and Pinacol Coupling of Aryl Aldehydes

Manganese-Mediated Reactions in Aqueous Media: Chemoselective Allylation and Pinacol Coupling of Aryl Aldehydes

ChemInform Abstract: Palladium‐ and Platinum‐Catalyzed Addition of Aldehydes and Imines with Allylstannanes. Chemoselective Allylation of Imines in the Presence of Aldehydes.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Radical induced allylations of functionalized α-haloalkylphenyl sulfones

α-Haloalkylphenyl sulfones are efficiently allylated using allyltributyltin in benzene at reflux in the presence of AIBN. Several functional groups (e.g. ester, keto, amino, nitro etc.) are tolerated by these conditions that ultimately allow the chemoselective allylation of phenylsulfones at α position.

Scandium trifluoromethanesulfonate-catalyzed chemoselective allylation reactions of carbonyl compounds with tetraallylgermane in aqueous media

Scandium(III) triflate-catalyzed allylation of carbonyl compounds with tetraallylgermane proceeded readily in aqueous nitromethane to afford homoallyl alcohols in excellent to good yields. The presence of H 2O is indispensable for the allylation of aldehydes to proceed smoothly. Aldehydes were allylated exclusively in the presence of ketone moieties.

Stereochemistry and Mechanism of the Chemoselective Allylation of alpha-Substituted beta-Keto Esters with Allyl Bromide Mediated by Zn in NH4Cl(aq)-THF.

Stereochemistry and Mechanism of the Chemoselective Allylation of alpha-Substituted beta-Keto Esters with Allyl Bromide Mediated by Zn in NH4Cl(aq)-THF.

ChemInform Abstract: Unprecedented Highly Chemoselective Allylation of Imines in the Presence of Aldehydes via a Palladium Catalyzed Allylstannane Reaction.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform Abstract: Palladium‐ and Platinum‐Catalyzed Addition of Aldehydes and Imines with Allylstannanes. Chemoselective Allylation of Imines in the Presence of Aldehydes.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

The solvent promoted addition of tetraallyltin to aldehydes: A convenient and chemoselective allylation procedure

Aldehydes 2a – e react with tetraallyltin ( 1,0.25 equiv.) in methanol or other polar solvent at room temperature ( ca 30°C, <20 h) to provide the corresponding homoallyl alcohols 3a – e in 69 – 98% yield. No additional catalysis is required.

Palladium- and Platinum-Catalyzed Addition of Aldehydes and Imines with Allylstannanes. Chemoselective Allylation of Imines in the Presence of Aldehydes

The reaction of allylstannanes 1 with aldehydes 2 in THF was catalyzed by Pd(II) or Pt(II) complexes (10 mol %) either at room temperature or at reflux, giving the corresponding homoallylic alcohols 3 in high to good yields. Among the catalysts examined, PtCl2(PPh3)2 gave the best result. No only allyltribitylstannane but also methallyl- and crotyltributylstannane could be utilized in this transition metal catalyzed reaction. Detailed mechanistic studies of the Pd(II)-catalyzed allylation, using NMR spectroscopy, revealed that the bis-π-allylpalladium complex is a key intermediate for the catalytic cycle and it exhibits nucleophilic reactivity. The nucleophilic reactivity of the intermediate is in marked contrast to the electrophilic reactivity of ordinary π-allylpalladium complexes (π-allylPdX, X = OAc, halogen, OCO2R, etc.). The addition of allyl-, crotyl-, and methallylstannanes to various imines 4 proceeded very smoothly to give the corresponding allylated products (homoallylic amines 5) in good to high yields. The reactivities of allylstannanes to imines were higher than those to aldehydes under the catalytic conditions, although it is known that the reactivity of allylstannanes to aldehydes is higher than that to imines under the Lewis acid promoted condition. Imines were chemoselectively allylated in the presence of aldehydes and the highest selectivities were obtained using π-allylpalladium chloride dimer 11 as a catalyst.

Unprecedented highly chemoselective allylation of imines in the presence of aldehydes via a palladium catalysed allylstannane reaction

Imines are allylated chemoselectively in the presence of aldehydes using allylstannanes with a π-allylpalladium chloride dimer catalyst.

ChemInform Abstract: Zn‐Mediated Chemoselective Allylation of Keto Esters with Allylic Halides in Aqueous Medium.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.