Hydroformylation and Isomerization of Allene and Propyne: A Density Functional Theory Study

Abstract

The [HCo(CO)3]-catalyzed hydroformylation of allene and propyne has been investigated at the B3LYP level of density functional theory. It is found that hydroformylation of allene favors the linear anti-Markovnikov product in high regioselectivity both kinetically and thermodynamically. The origin of this regioselectivity comes from the enhanced stability of the eta3-allylic intermediate [(eta3-CH2CHCH2)Co(CO)3]. By contrast, propyne does not show any regioselectivity. The possible interconversion between allene and propyne mediated by [HCo(CO)3] has been explored.

Computational aspects of hydroformylation

“…This type of reaction was studied by HLBJ employing B3LYP/6-311+G(d) level of theory. 71 The relative stability of the syn-h 3 -allylic intermediate was found to account for the regioselectivity as the linear anti-Markovnikov intermediate was more stable by 16.3 kcal mol À1 than the branched Markovnikov intermediate (Fig. 6).…”

“…This type of reaction was studied by HLBJ employing B3LYP/6-311+G(d) level of theory. 71 The (Fig. 6).…”

Rhodium‐Catalyzed Hydroformylation of 1,1‐Disubstituted Allenes Employing the Self‐Assembling 6‐DPPon System

“…In 1976 Fell and Beutler performed studies on the hydroformylation of allene and found complex mixtures of mono‐ and dialdehydes 5a. DFT calculations by Jiao, Beller, and co‐workers suggested that coupling at the terminal sp 2 ‐carbon of allene should be thermodynamically and kinetically favored over the reaction at the sp‐center 5b. The only chemoselective hydroformylation of allenes is in agreement with this theory and converts a 1,2‐allenyl‐phosphine oxide into the corresponding linear saturated aldehyde (aldehyde 3 in Scheme ) 5c.…”

Regioselective Rh-Catalyzed Hydroformylation of 1,1,3-Trisubstituted Allenes Using BisDiazaPhos Ligand

“…Over 40 years ago, Fell and Beutler reported a single example of the hydroformylation of a terminal allene catalyzed by HRh­(CO) (PPh 3 ) 3 to produce complex mixtures of mono- and dialdehydes as products . Nearly three decades after this initial report, Jiao et al carried out computational studies of Co-catalyzed allene hydroformylation and surmised that addition of H to the central carbon of the allene to give an η 3 –allyl complex is both kinetically and thermodynamically preferred . This prediction was borne out in 2015, when the Breit group demonstrated the hydroformylation of 1,1-disubstituted allenes using catalytic Rh­(acac)­(CO) 2 supported by a 6-DPPon ligand (Table ) at 430 psi, producing β,γ-unsaturated aldehydes in good yields and varying Z / E ratios …”