Spiroketal-Based Phosphorus Ligands for Highly Regioselective Hydroformylation of Terminal and Internal Olefins

Robust, scalable, and highly selective spirocyclic catalysts for industrial hydroformylation and isomerization-hydroformylation

Hydroformylation (HF) or isomerization-hydroformylation (ISO-HF) represents the most direct and practical route for producing aldehydes on an industrial scale. To resolve the issues of low activity, low linear/branched (l/b) ratio, and low stability in HF and ISO-HF, we herein reported a class of spirocyclic diphosphites. Notably, the ligand termed O-SDPhite afforded excellent catalytic activity and regioselectivity for the HF of various olefins. Excellent l/b ratio and an unprecedented turnover number of up to 17,620,000 were achieved. O-SDPhite was also found to be effective in the regioselective ISO-HF of the industrially related cheap and abundant C4 Raffinates to n-valeraldehyde produced on a multimillion-ton scale. The reaction with O-SDPhite, superior to that of benchmark Biphephos, was continuously operated for 41 days and afforded an average 38.6 l/b ratio (31 days and 14.7 l/b ratio for Biphephos).

Revisiting the Preparation and Catalytic Performance of a Phosphine-Modified Co(II) Hydroformylation Precatalyst

In light of recent conflicting reports regarding the hydroformylation catalytic activity derived from cationic Co(II) precatalysts of the form [Co(acac)(bis(phosphine))]BF4, the synthetic procedures and characterization of [Co(acac)(dppBz)]BF4, 1, are evaluated. Leveraging calibrated ESI-TOF MS methodologies, substantial quantities of Co(acac)2(dppBz), 2, were observed within samples of 1. The source of the impurity, 2, is determined to derive from incomplete protonolysis of the Co(acac)2 precursor and ligand scrambling occurring during the synthesis of 1. Revised synthetic procedures using lower temperature conditions and longer reaction times afford analytically pure samples of 1 based on ESI-TOF MS and NMR spectroscopic analysis. Complex 1 is demonstrated to act as a hydroformylation precatalyst for the conversion of 1-hexene to 1-heptanal under relatively mild conditions at 51.7 bar and 140 °C. The presence of impurity 2 is shown to dramatically decrease the catalytic performance derived from 1.

Iridium-phosphine ligand complexes as an alternative to rhodium-based catalysts for the efficient hydroformylation of propene

Expensive rhodium (Rh)-based catalysts have been widely used for the hydroformylation of propene. To find a cheaper and effective alternative to these Rh-based catalysts, herein, a series of phosphine ligands were used to coordinate with iridium, and their catalytic reactivities for the hydroformylation of propene were systematically investigated in this study. The effects of different phosphine ligands, pressures, temperatures, and catalyst dosages on the hydroformylation of propene were investigated. Tripyridyl phosphine iridium Ir2(cod)2Cl2-P(3-py)3 (Ir(I)-L5) and its derivatives exhibit the highest catalytic reactivity. Surprisingly, the catalytic reactivity of Ir(I)-L5 is higher than that of Rh2(cod)2Cl2-P(3-py)3 (Rh(I)-L5). When the Ir(I)-L5 complex is used as the catalyst, reactions performed in a polar solvent gave higher turnover number (TON) values than those in a non-polar solvent. Up to a TON of 503 can be obtained. Different n-butyraldehyde/iso-butyraldehyde (n/i) ratios can be obtained by adjusting the phosphine ligands or the proportion of gas pressure. The catalyst showed good reusability in five recycling experiments. Furthermore, based on DFT theoretical calculations, a probable reaction mechanism was proposed. It is reliable that an Ir-based catalyst can be considered as a highly effective catalyst for the hydroformylation of propylene with CO.

A diphosphoramidite ligand for hydroformylation of various olefins

A new rotationally hindered diphosphoramidite ligand has been applied to the Rh-catalyzed hydroformylation of various olefins. Good activity as well as excellent regioselectivity toward the formation of linear aldehydes were achieved. Remarkable performances were also observed in the hydroformylation of functionalized olefins, including methyl acrylate, allyl acetate, crotonaldehyde ethylene acetal and styrene.

Hydroformylation catalyzed by unmodified cobalt carbonyl under mild conditions

Hydroformylation with unmodified cobalt carbonyl catalyst plays a crucial role in industrial production of surfactants and plasticizers. However, syngas pressures of 100 to 400 bar with reaction temperatures of 100° to 250°C are typically applied. We report here that unmodified cobalt carbonyl is a stable hydroformylation catalyst at 140°C under 30 bar of syngas. The activity was comparable to that of recently reported bisphosphine-coordinated cobalt(II) catalysts, which we could not reproduce under the reported conditions. Kinetic and in situ infrared spectroscopic studies confirmed the stability of the unmodified cobalt tetracarbonyl hydride [HCo(CO)₄]. Branched internal olefins were converted to aldehydes with high regioselectivity under low syngas pressures without phosphorus ligands. Bisphosphines had a small promotional effect on the catalyst at phosphorus-to-cobalt loading ratios below 0.6.

Modular Synthesis of Halogenated Xanthones by a Divergent Coupling Strategy

A versatile strategy to halogenated xanthones was developed that relies on a modular coupling of vanillin derivatives with a dibromoquinone. Depending on the reaction conditions, either the 6- or the 7-bromo heterocycles may be obtained in a divergent manner. These heterocycles may be readily further elaborated by sequential Sonogashira couplings, and the sequence may be successfully applied to substructures of the antibiotic lysolipin.

A heterogeneous Rh/CPOL-BINAPa&PPh3 catalyst for hydroformylation of olefins: chemical and DFT insights into active species and the roles of BINAPa and PPh3

A reusable Rh/CPOL-BINAPa&PPh3 catalyst was used for heterogeneous hydroformylation of olefins, affording the corresponding linear aldehydes with excellent regioselectivities and high TON values. The active Rh–H species were studied in detail.

Selective Rhodium-Catalyzed Hydroformylation of Terminal Arylalkynes and Conjugated Enynes to (Poly)enals Enabled by a π-Acceptor Biphosphoramidite Ligand

The hydroformylation of terminal arylalkynes and enynes offers a straightforward synthetic route to the valuable (poly)enals. However, the hydroformylation of terminal alkynes has remained a long-standing challenge. Herein, an efficient and selective Rh-catalyzed hydroformylation of terminal arylalkynes and conjugated enynes has been achieved by using a new stable biphosphoramidite ligand with strong π-acceptor capacity, which affords various important E-(poly)enals in good yields with excellent chemo- and regioselectivity at low temperatures and low syngas pressures.

State-of-the-art palladium-catalyzed alkoxycarbonylations

State-of-the-art Pd-catalyzed alkoxycarbonylation: catalyst development and applications.

Rh-catalyzed highly regioselective hydroformylation to linear aldehydes by employing porous organic polymer as a ligand

In this work, we developed a new structural porous organic polymer containing biphosphoramidite unit, which can be used as a solid bidentate phosphorous ligand for rhodium-catalyzed solvent-free higher olefins hydroformylation. The resultant catalyst demonstrated unprecedently high regioselectivity to linear aldehydes and could be readily recovered for successive reuses with good stability in both catalytic activity and regioselectivity.

A porous organic polymer as a ligand was designed and prepared for Rh-catalyzed hydroformylation with outstanding activity and unprecedently high regioselectivity to linear aldehyde.

Porous Organic Polymer Supported Rhodium as a Reusable Heterogeneous Catalyst for Hydroformylation of Olefins

A new porous organic polymer has been prepared via copolymerization of divinyl-functionalized phosphoramidite ligand and tris(4-vinylphenyl)phosphine. The porous polymer was loaded with Rh(acac)CO₂ to yield a supported Rh catalyst, which demonstrated good regioselectivity ( l/ b = 6.7-52.8) and high catalytic activity (TON up to 45.3 × 10⁴) in hydroformylation of terminal and internal olefins. Remarkably, the heterogeneous catalyst can be reused at least 10 cycles without losing activity and selectivity in hydroformylation of 1-hexene.

Synergistic silver/scandium catalytic spiroketalization of β-alkynyl ketones for the atom economical synthesis of skeletally diverse spirocyclic isochromenes

Two types of new synergistic silver/scandium catalytic spiroketalizations of β-alkynyl ketones have been achieved, delivering a variety of skeletally diverse spirocyclic isochromenes in generally good yields.

Development of efficient palladium catalysts for alkoxycarbonylation of alkenes

Herein, we report a general and efficient Pd-catalysed alkoxycarbonylation of sterically hindered and demanding olefins including a variety of tri-, tetra-substituted and 1,1-disubstituted alkenes. In the presence of 1,3-bis(tert-butyl(pyridin-2-yl)phosphanyl)propane L3 or 1,4-bis(tert-butyl(pyridin-2-yl)phosphanyl)butane L4 the desired esters are obtained in good yields and selectivities. Similar transformation is obtained using tertiary ether as showcased in the carbonylation of MTBE to the corresponding linear ester in high yield and selectivity.

Synergistic silver/scandium catalysis for divergent synthesis of skeletally diverse chromene derivatives

The combination of AgTFA and Sc(OTf)₃ enables the bimetallic synergistic catalysis of β-alkynyl ketones and o-hydroxybenzyl alcohols, allowing divergent synthesis of three classes of skeletally diverse chromene derivatives with generally high diastereoselectivity through dehydroxylated bi- and tri-cyclization cascades.

Palladium-catalyzed asymmetric allylic amination: enantioselective synthesis of chiral α-methylene substituted β-aminophosphonates

Palladium catalyzed asymmetric allylic amination of 2-diethylphosphonate-substituted allylic acetates in the presence of SKP ligands afforded the corresponding chiral β-aminophosphonates in good yields, high regioselectivities, and excellent enantioselectivities.

Designing highly efficient Rh/CPOL-bp&PPh3 heterogenous catalysts for hydroformylation of internal and terminal olefins

Vinyl functionalized Biphephos ligand, denoted as vinyl biphephos, has been succesfully synthesized.

Highly regioselective osmium-catalyzed hydroformylation

The first highly regioselective and general osmium-catalyzed hydroformylation of olefins to aldehydes is reported. The combination of Os3(CO)12 and imidazoyl-substituted phosphine ligands allows n-selective (up to 99%) hydroformylation of bulk aliphatic as well as functional alkenes in good yields (64-87%).

A novel rhodium-catalyzed domino-hydroformylation-reaction for the synthesis of sulphonamides

An efficient and highly selective domino hydroformylation-reductive sulphonamidation reaction has been developed for the synthesis of sulphonamides using a rhodium/phosphine catalyst.

Using aqueous ammonia in hydroaminomethylation reactions: ruthenium-catalyzed synthesis of tertiary amines

The direct synthesis of tertiary amines from ammonia and olefins is presented. Using a combination of Ru3 (CO)12 and 2-phosphino-substituted imidazole ligand as catalyst system allows for hydroaminomethylation reactions of bulk aliphatic and functionalized olefins. Tertiary amines are obtained in an atom-efficient domino process in moderate to good isolated yields (45-76%) with excellent regioselectivities (n/iso up to 99:1).

Synthesis and application of a new triphosphorus ligand for regioselective linear hydroformylation: a potential way for the stepwise replacement of PPh3 for industrial use

A new triphosphorus ligand, Tribi, for regioselective linear hydroformylation of terminal and internal olefins with excellent catalytic activity and regioselectivity.

Rhodium-catalyzed regioselective hydroaminomethylation of terminal olefins with pyrrole-based tetraphosphorus ligands

A protocol was developed to prepare linear amines by regioselective hydroaminomethylation of terminal olefins with pyrrole-based tetraphosphorus ligands. The reactivity of the ligand is modulated by the substituent of the biphenylphosphane moiety, with ligand L5 exhibiting the highest reactivity.