Palladium-Catalyzed Carbonyl Allylation Research Articles

Palladium-Catalyzed Carbonyl Allylation of Aldehydes and Isatins

Key words palladium - aldehydes - isatins - allylation - olefins

ChemInform Abstract: Palladium-Catalyzed Carbonyl Allylation by 2-(Hydroxymethyl)acrylate Derivatives: Synthesis of α-Methylene-γ-butyrolactones.

Abstract Ethyl 2-(Hydroxymethyl)acrylate derivatives serve as reagents for 2-ethoxycarbonylallylation of carbonyl compounds using PdCl2(PhCN)2-SnCl2 system to produce α-methylene-γ-butyrolactones diastereoselectivity.

Palladium-Catalyzed Carbonyl Allylation: Synthesis of Enantiomerically Pure α-Substituted Allylboronic Esters

Palladium-catalyzed carbonyl allylation of stable alkenylboronic ester with SnCl2 proceeded diastereoselectively to afford α-substituted allylboronic esters; the assignment of their configuration as well as allyl additions are presented.

Fluorous-Phase Synthesis of α-Methyleneγ-lactones

Fluorous-phase organic synthesis (FPOS) was employed for the sequential Baylis-Hilman and palladium-catalyzed carbonyl allylation reactions providing a synthesis of mono- and disubstituted α-methylene-γ-lactones. The intermediates were purified by solid-phase extraction using reverse-phase fluorous silica gel (FSPE). The α-methylene-γ-lactone derivatives were formed in high cis selectivity (up to ˜100%), except for the methoxyphenyl-substituted aldehyde which led to only a slight excess of the cis diastereoisomer. Both aliphatic and aromatic aldehydes were shown to participate in the reaction although the scope was not widely investigated.

A solid-phase version of the palladium-catalyzed carbonyl allylation by allylic alcohols with SnCl 2

A solid-phase version of the palladium-catalyzed carbonyl allylation of aldehydes by allylic alcohols is described. Preliminary studies have been carried out with resin bound aldehydes 1a– c and different allylic alcohols. Solvent effects as well as the regio- and diastereoselectivity of our solid-phase conditions are compared with solution-phase protocols.

Chelation-Controlled Regioselection in Palladium-Catalyzed Carbonyl Allylation by 4-Pentene-1,3-Diol or Its Cyclic Carbonate

With cat. PdCl2(PhCN)2 and SnCl2, 4-pentene-1,3-diol caused regioselective carbonyl allylation at 3-position in DMF to produce 2-substituted 3-vinyltetrahydrofurans and/or 1-substituted 2-vinylbutane-1,4-diols, and cyclic carbonate of 4-pentene-1,3-diol caused regioselective carbonyl allylation at terminal 5-position in THF to produce 1-substituted 3-hexene-1,6-diols.

Palladium-Catalyzed Carbonyl Allylation of Aldehydes with Allylic Phosphates: Synthesis of Homoallylic Alcohols

Abstract Allylation of aldehydes by reaction allylic phosphates with diethylzinc in the presence of Pd(PPh3)4 afforded homoallylic alcohol via nucleophilic allylzinc species.

Palladium-Catalyzed Carbonyl Allylation of Aldehydes by Allylic Cyclic Carbonates

Abstract Palladium(O)-catalyzed allylation of aldehydes by allylic cyclic carbonates with SnCl2 proceeded smoothly to afford 1,3-diols with high diastereocontrol. For the exomethylene cyclic carbonate, allylation with aldehydes furnished 1,4-diols or 1,5-diols depending on amount of aldehydes.

Ultrasound-promoted palladium-catalyzed carbonyl allylation by allylic alcohols with tin(II) chloride in non-polar solvents

Heterogeneous ultrasound-promoted palladium-catalyzed carbonyl allylation by γ-substituted allylic alcohols with tin(II) chloride in non-polar solvents such as diethyl ether, diisopropyl ether and toluene was carried out stepwise (first, the formation of allylic tin intermediates by ultrasonication, followed by the allylation of aldehydes by the intermediates) to produce 1,4-disubstituted 3-buten-1-ols regioselectively in moderate yields. The regioselectivity (α-selection) in the ultrasound-promoted reaction is the inverse of that (γ-selection) in the homogeneous palladiumcatalyzed carbonyl allylation in polar solvents such as 1,3-dimethyl-2-imidazolidinone, DMF, DMSO and ethylene glycol. The more bulky the γ-substituent, the higher is the α-regioselectivity.

In Turn or in Reverse Palladium-Catalyzed Carbonyl Allylation and Diels-Alder Reaction by 2-Methylene-3-buten-1-ol

Abstract Using PdCl2(PhCN)2-SnCl2, 2-methylene-3-buten-2-ol causes carbonyl allylation of various aldehydes to afford 1-substituted-3-methylene-4-penten-1-ols; the Diels-Alder reaction of those with dienophiles produces 1-(2-hydroxyethyl)cyclohexenes. Diels-Alder reaction of 2-methylene-3-buten-1-ol with dienophiles followed by carbonyl allylation produces structurally isomeric 1-methylene-2-(hydroxymethyl)cyclohexanes.

Palladium-catalyzed intramolecular carbonyl allylation via Claisen rearrangement

Palladium-catalyzed intramolecular carbonyl allylation with SnCl 2 by 5-substituted 4-methylene-5-(2-tetrahydropranyloxy)pentanals, prepared by Claisen rearrangement of 2-[1-(2-tetrahydropyranyloxy)alkyl]allyl vinyl ethers, occurred radioselectively at ambient temperature in DMI/H 2O to give 2-substituted 3-methylenecyclopentanols in good yields.

Palladium-catalyzed carbonyl allylation by allylic alcohols with stannous chloride

Allylation of carbonyls via activation of allylic alcohols on palladium catalysts is reported. SnCl{sub 2} acts as a reducing agent. Regioselectivity of the reactions was evaluated in terms of solvent effects. Further, reaction intermediates were observed by NMR. 46 refs., 14 figs., 5 tabs.

π‐アリルパラジウム錯体の見かけ上の電荷反転 アリルアルコール類によるカルボニル‐アリル化反応への応用

Palladium-catalyzed carbonyl allylation by allylic alcohols with SnCl2 smoothly proceeds in aqueous medium under air. The actual allylating agent in the carbonyl allylation by allyl alcohol in dry medium is allyltrichlorotin, which is prepared via (1) oxidative addition of allyl alcohol to Pd (0) complex with SnCl2, (2) insertion of SnCl2 to π-allylpalladium complex, followed by (3) reductive elimination of π-allylpalladium trichlorostannate. Allylic alcohols, preparing π-allylpalladium complexes, function as synthons of allylic carbanions. In other words, this implies the apparent charge reversal of electrophilic π-allylpalladium complexes. The carbonyl allylation by allylic alcohols can achieve high chemo-, regio-, and diastereoselection by the choice of solvent, and can be applied to chelation-controlled diastereoselection in polar solvents.

Palladium-catalyzed carbonyl allylation by 2-(hydroxymethyl)acrylate derivatives: synthesis of α-methylene-γ-butyrolactones

Ethyl 2-(Hydroxymethyl)acrylate derivatives serve as reagents for 2-ethoxycarbonylallylation of carbonyl compounds using PdCl 2(PhCN) 2-SnCl 2 system to produce α-methylene-γ-butyrolactones diastereoselectivity.

Palladium-Catalyzed Carbonyl Allylation of Diketo Compounds by Allylic Alcohols with SnCl2

Abstract Palladium-catalyzed diallylation of 1,2-diketones and 1,2-ketoaldehyde by allyl alcohol with SnCl2 in DMI was accelerated and proceeded diastereoselectively thanks to a chelation of a carbonyl group to Sn(IV) (tin alkoxide) in the corresponding monoallylated intermediates.

Palladium-catalyzed carbonyl allylation by allylic alcohols with SnCl 2. A solvation-controlled diastereoselection

Diastereocontrol in the allylation of benzaldehyde by (E)-but-2-en-1-ol using catalyst PdCl 2(PhCN) 2 and SnCl 2 was achieved by the choice of polar solvents; use of DMSO at 25 °C led to syn selection, while anti selection was found at -10 °C in THF. The addition of 3–10 equivalents of H 2O in any solvent enhanced the selectivities, and the control of the amount of H 2O in DMSO permitted both syn selection (a small amount of H 2O) and anti selection (a large amount of H 2O).

Allylic alcohols as synthons of allylic carbanions. Palladium-catalyzed carbonyl allylation by allylic alcohols with tin dichloride

L'allylation des aldehydes est chimioselective et a ete effectuee en presence du groupement cetone