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Synthesis of unsymmetrical alkyl acetals via addition of primary alcohols to allyl ethers mediated by ruthenium complexes.

Krompiec S, Penkala M, Kowalska E, Penczek R, Bujak P, Danikiewicz W, Spólnik G, Kita A, Grudzka I - Monatsh. Chem. (2011)

Bottom Line: Ru-catalyzed synthesis of mixed alkyl-alkyl acetals via addition of primary alcohols to allyl ethers has been extended to include long-chain and/or functionalized substrates.Of particular importance is the almost quantitative elimination of transacetalization.The addition proceeds through allyl complexes, not via isomerization of allyl ethers--subsequent addition of ROH to vinyl ethers.

View Article: PubMed Central - PubMed

Affiliation: Institute of Chemistry, University of Silesia, Katowice, Poland.

ABSTRACT

Abstract: Ru-catalyzed synthesis of mixed alkyl-alkyl acetals via addition of primary alcohols to allyl ethers has been extended to include long-chain and/or functionalized substrates. The catalytic systems for these reactions were generated from RuCl2(PPh3)3 and [RuCl2(1,5-COD)]x and phosphines [PPh3 or P(p-chlorophenyl)3] or SbPh3. Of particular importance is the almost quantitative elimination of transacetalization. The addition proceeds through allyl complexes, not via isomerization of allyl ethers--subsequent addition of ROH to vinyl ethers.

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Sch1:  

Mentions: According to our previous reports [14, 15], the proposed mechanism of the studied reaction of the addition of alcohols to allyl ethers is presented in Scheme 1. The first step consists of the oxidative addition of the allyl ether to [Ru] through a C(allyl)–H bond, and the hydrido-π-allyl complex I1 is formed. Reductive elimination of allyl/H ligands generates the vinyl ether, while the reaction with R2OH results in the formation of the complex I2. Migration of R2O to the coordinated allyl ligand leads to the complex I3 containing the coordinated, unsaturated acetal and two hydride ligands. Rapid hydrogenation follows through the complex I4 and the mixed acetal P2 is formed. The complex I3 can also be formed directly from I1 through the transition state TS.Scheme 1


Synthesis of unsymmetrical alkyl acetals via addition of primary alcohols to allyl ethers mediated by ruthenium complexes.

Krompiec S, Penkala M, Kowalska E, Penczek R, Bujak P, Danikiewicz W, Spólnik G, Kita A, Grudzka I - Monatsh. Chem. (2011)

 
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4495020&req=5

Sch1:  
Mentions: According to our previous reports [14, 15], the proposed mechanism of the studied reaction of the addition of alcohols to allyl ethers is presented in Scheme 1. The first step consists of the oxidative addition of the allyl ether to [Ru] through a C(allyl)–H bond, and the hydrido-π-allyl complex I1 is formed. Reductive elimination of allyl/H ligands generates the vinyl ether, while the reaction with R2OH results in the formation of the complex I2. Migration of R2O to the coordinated allyl ligand leads to the complex I3 containing the coordinated, unsaturated acetal and two hydride ligands. Rapid hydrogenation follows through the complex I4 and the mixed acetal P2 is formed. The complex I3 can also be formed directly from I1 through the transition state TS.Scheme 1

Bottom Line: Ru-catalyzed synthesis of mixed alkyl-alkyl acetals via addition of primary alcohols to allyl ethers has been extended to include long-chain and/or functionalized substrates.Of particular importance is the almost quantitative elimination of transacetalization.The addition proceeds through allyl complexes, not via isomerization of allyl ethers--subsequent addition of ROH to vinyl ethers.

View Article: PubMed Central - PubMed

Affiliation: Institute of Chemistry, University of Silesia, Katowice, Poland.

ABSTRACT

Abstract: Ru-catalyzed synthesis of mixed alkyl-alkyl acetals via addition of primary alcohols to allyl ethers has been extended to include long-chain and/or functionalized substrates. The catalytic systems for these reactions were generated from RuCl2(PPh3)3 and [RuCl2(1,5-COD)]x and phosphines [PPh3 or P(p-chlorophenyl)3] or SbPh3. Of particular importance is the almost quantitative elimination of transacetalization. The addition proceeds through allyl complexes, not via isomerization of allyl ethers--subsequent addition of ROH to vinyl ethers.

No MeSH data available.


Related in: MedlinePlus