71640-85-2

Upstream product

• 39497-64-8 3,3-dimethyl-2-methylenebutan-1-ol 
• 100911-55-5 2,3,3-trimethylbutane-1,2-diol 
• 69060-18-0 3,3-dimethyl-2-methylenebutanal 
• 28523-40-2 2-(tert-butyl)-2-methyloxirane 
• 35155-60-3 1-methoxy-2,3,3-trimethyl-butan-2-ol 
• 5750-00-5 2,2-dimethyl-3-butyl chloride 
• 122-51-0 orthoformic acid triethyl ester 
• 558-37-2 tert-butylethylene 
• 201230-82-2 carbon monoxide 
• 36794-64-6 2,3,3-trimethylbutan-1-ol 
• 917-54-4 methyllithium 
• 107-39-1 2,4,4-trimethyl-1-pentene 
• 10028-15-6 ozone 
• 141-70-8 1,1-dineopentylethylene 

Downstream Products

• 92-52-4 biphenyl 
• 71640-82-9 β-1-phenyl-2,3,3-trimethylbutan-1-ol 
• 167367-69-3 (E)-1-bromo-2-(3',4',4'-trimethylpent-1'-enyl)benzene 
• 908261-07-4 4,7,7-trimethyl-3-oxo-2-oxa-bicyclo[2.2.1]heptane-1-carboxylic acid 2,3,3-trimethyl-1-phenyl-butyl ester 
• 908261-08-5 (-)-syn-2,3,3-trimethyl-1-phenyl-butan-1-ol 

Relevant academic research and scientific papers

Understanding a Hydroformylation Catalyst that Produces Branched Aldehydes from Alkyl Alkenes

This paper reports experimental and computational studies on the mechanism of a rhodium-catalyzed hydroformylation that is selective for branched aldehyde products from unbiased alkene substrates. This highly unusual selectivity relies on a phospholane-phosphite ligand prosaically called BOBPHOS. Kinetic studies using in situ high pressure IR (HPIR) and the reaction progress kinetic analysis methodology suggested two steps in the catalytic cycle were involved as turnover determining. Negative order in CO and positive orders in alkene and H2 were found and the effect of hydrogen and carbon monoxide partial pressures on selectivity were measured. Labeling studies found rhodium hydride addition to the alkene to be largely irreversible. Detailed spectroscopic HPIR and NMR characterization of activated rhodium-hydrido dicarbonyl species were carried out. In the absence of H2, reaction of the rhodium-hydrido dicarbonyl with allylbenzene allowed further detailed spectroscopic characterization of four- and five-coordinate rhodium-acyl species. Under single-turnover conditions, the ratios of branched to linear acyl species were preserved in the final ratios of aldehyde products. Theoretical investigations uncovered unexpected stabilizing CH-π interactions between the ligand and substrate which influenced the high branched selectivity by causing potentially low energy pathways to become unproductive. Energy span and degree of TOF control analysis strongly support experimental observations and mechanistic rationale. A three-dimensional quadrant model was built to represent the structural origins of regio- and enantioselectivity.

Crucial role of additives in iridium-catalyzed hydroformylation

Abstract This paper presents the new highly selective iridium-catalyzed hydroformylation of 1-octene with an Ir(cod)(acac)/PPh3/salt catalyst system. The addition of inorganic salts such as LiCl suppresses the hydrogenation of 1-octene and increases the yield of desired hydroformylation products. Even low amounts of LiCl (LiCl/Ir = 2/1) significantly increase the chemoselectivity of aldehydes up to 94% with a 1-octene conversion of 90% within 7 h. This catalyst is applicable to other alkenes such as 1-pentene or 1-dodecene. The high selectivities and the remarkable activity of the optimized iridium catalyst are promising in terms of successfully implementing on an industrial scale in the future.

Chiral propargylic cations as intermediates in SN1-type reactions: Substitution pattern, nuclear magnetic resonance studies, and origin of the diastereoselectivity

Nine propargylic acetates, bearing a stereogenic center (-C*HXR 2) adjacent to the electrophilic carbon atom, were prepared and subjected to SN1-type substitution reactions with various silyl nucleophiles employing bismuth trifluoromethanesulfonate [Bi(OTf)3] as the Lewis acid. The diastereoselectivity of the reactions was high when the alkyl group R2 was tertiary (tert-butyl), irrespective of the substituent X. Products were formed consistently with a diastereomeric ratio larger than 95:5 in favor of the anti-diastereoisomer. If the alkyl substitutent R2 was secondary, the diastereoselectivity decreased to 80:20. The reaction was shown to proceed stereoconvergently, and the relative product configuration was elucidated. The reaction outcome is explained by invoking a chiral propargylic cation as an intermediate, which is preferentially attacked by the nucleophile from one of its two diastereotopic faces. Density functional theory (DFT) calculations suggest a preferred conformation in which the group R2 is almost perpendicular to the plane defined by the three substituents at the cationic center, with the nucleophile approaching the electrophilic center opposite to R2. Transition states calculated for the reaction of allyltrimethylsilane with two representative cations support this hypothesis. Tertiary propargylic cations with a stereogenic center (-C* HXR2) in the α position were generated by ionization of the respective alcohol precursors with FSO3H in SO2ClF at -80 C. Nuclear magnetic resonance (NMR) spectra were obtained for five cations, and the chemical shifts could be unambiguously assigned. The preferred conformation of the cations as extracted from nuclear Overhauser experiments is in line with the preferred conformation responsible for the reaction of the secondary propargylic cations.

Kinetic explanation for the temperature dependence of the regioselectivity in the hydroformylation of neohexene

The kinetics of Rh-catalyzed neohexene hydroformylation were investigated with the bulky monodentate ligand tris(2,4-di-tert-butylphenyl)phosphite. The hydrogenolysis of the Rh-acyl intermediate was identified as the rate-limiting step for both the linear and the branched aldehydes. Rate equations for both aldehydes were derived and kinetic parameters were estimated. Increased aldehyde linearity at higher temperatures, frequently observed in hydroformylation, was elucidated by deuterioformylation experiments. These showed that at 100 °C the formation of linear Rh-alkyl was more reversible than the formation of the branched derivative. The ratio of linear to branched Rh-acyl species was determined by in situ high-pressure IR spectroscopy experiments, which allowed the difference in the activation energies for the hydrogenolysis steps towards the aldehyde isomers to be quantified. The hydrogenolysis of Rh-acyl was found to be the step that caused the greatest temperature effect on the regioselectivity. Kinetics arouses curiosity: Studying the kinetics of neohexene hydroformylation catalyzed by a bulky-phosphite-modified Rh catalyst brings up the question: "What is the reason behind the temperature dependence of regioselectivity?" We answer this question by using mechanistic tools such as deuterium labeling and in situ IR spectroscopy. The hydrogenolysis step of the catalytic cycle seems to be the main step that is responsible. Copyright

An operando FTIR spectroscopic and kinetic study of carbon monoxide pressure influence on rhodium-catalyzed olefin hydroformylation

The influence of carbon monoxide concentration on the kinetics of the hydroformylation of 3,3-dimethyl-1-butene with a phosphite-modified rhodium catalyst has been studied for the pressure range p(CO)=0.20-3.83MPa. Highly resolved time-dependent concentration profiles of the organometallic intermediates were derived from IR spectroscopic data collected in situ for the entire olefin-conversion range. The dynamics of the catalyst and organic components are described by enzyme-type kinetics with competitive and uncompetitive inhibition reactions involving carbon monoxide taken into account. Saturation of the alkyl-rhodium intermediates with carbon monoxide as a cosubstrate occurs between 1.5 and 2 MPa of carbon monoxide pressure, which brings about a convergence of aldehyde regioselectivity. Hydrogenolysis of the acyl intermediate is fast at 30'°C and low pressure of p(CO)=0.2 MPa, but is of minus first order with respect to the solution concentration of carbon monoxide. Resting 18-electron hydrido and acyl complexes that correspond to early and late rate-determining states, respectively, coexist as long as the conversion of the substrate is not complete.

Rhodium catalyzed hydroformylation with formaldehyde and an external H 2-source

The efficiency of the syngas-free rhodium catalyzed hydroformylation of olefins with formaldehyde can be significantly improved by the addition of hydrogen gas or formic acid.

Exploring between the extremes: Conversion-dependent kinetics of phosphite-modified hydroformylation catalysis

The kinetics of the hydroformylation of 3,3-dimethyl-1-butene with a rhodium monophosphite catalyst has been studied in detail. Time-dependent concentration profiles covering the entire olefin conversion range were derived from in situ high-pressure FTIR spectroscopic data for both, pure organic components and catalytic intermediates. These profiles fit to Michaelis-Menten-type kinetics with competitive and uncompetitive side reactions involved. The characteristics found for the influence of the hydrogen concentration verify that the pre-equilibrium towards the catalyst substrate complex is not established. It has been proven experimentally that the hydrogenolysis of the intermediate acyl complex remains rate limiting even at high conversions when the rhodium hydride is the predominant resting state and the reaction is nearly of first order with respect to the olefin. Results from in situ FTIR and high-pressure (HP) NMR spectroscopy and from DFT calculations support the coordination of only one phosphite ligand in the dominating intermediates and a preferred axial position of the phosphite in the electronically saturated, trigonal bipyramidal (tbp)-structured acyl rhodium complex. Copyright

Catalytic asymmetric reductive amination of aldehydes via dynamic kinetic resolution

A novel organocatalytic asymmetric reductive amination of aldehydes has been developed. Treating racemic α-branched aldehydes with p-anisidine and a Hantzsch ester in the presence of our previously developed phosphoric acid catalyst, TRIP, gave β-branched secondary amines in excellent yields and enantioselectivities via an efficient dynamic kinetic resolution. The process is applicable to several different aromatic aldehydes and amines but gives slightly reduced enantiomeric ratios with aliphatic aldehydes. Copyright

On the constitutional stability of η1-allylmetal compounds

Many η1-allymetal species undergo a rapid haptotropic rearrangement. The stereochemical outcome of reactions of these allylmetal species with aldehydes depends on whether the haptotropic rearrangement is faster or slower than the reaction with

Diastereoselectivity of the thio-Claisen rearrangement of acyclic precursors bearing a chiral centre adjacent to carbon 6

A number of chiral allylic alcohols have been prepared and submitted to a Mitsunobu reaction with dithioacetic acid. Allyl dithioesters were deprotonated by LDA at -30°C and resulting enethiolates were quenched with iodomethane to afford quantitatively S-