Alkene isomerization-hydroboration promoted by phosphine-ligated cobalt catalysts

Alkene Isomerization Catalyzed by a Mn(I) Bisphosphine Borohydride Complex

An additive-free manganese-catalyzed isomerization of terminal alkenes to internal alkenes is described. This reaction is implementing an inexpensive nonprecious metal catalyst. The most efficient catalyst is the borohydride complex cis-[Mn(dippe)(CO)2(κ2-BH4)]. This catalyst operates at room temperature, with a catalyst loading of 2.5 mol %. A variety of terminal alkenes is effectively and selectively transformed into the respective internal E-alkenes. Preliminary results show chain-walking isomerization at an elevated temperature. Mechanistic studies were carried out, including stoichiometric reactions and in situ NMR analysis. These experiments are flanked by computational studies. Based on these, the catalytic process is initiated by the liberation of "BH3" as a THF adduct. The catalytic process is initiated by double bond insertion into an M-H species, leading to an alkyl metal intermediate, followed by β-hydride elimination at the opposite position to afford the isomerization product.

Selective Hydroboration of C-C Single Bonds without Transition-Metal Catalysis

Selective hydroboration of C-C single bonds presents a fundamental challenge in the chemical industry. Previously, only catalytic systems utilizing precious metals Ir and Rh, in conjunction with N- and P- ligands, could achieve this, ensuring bond cleavage and selectivity. In sharp contrast, we discovered an unprecedented and general transition-metal-free system for the hydroboration of C-C single bonds. This methodology is transition-metal and ligand-free and surpasses the transition-metal systems regarding chemo- and regioselectivities, substrate versatility, or yields. In addition, our system tolerates various functional groups such as Ar-X (X=halides), heterocyclic rings, ketones, esters, amides, nitro, nitriles, and C=C double bonds, which are typically susceptible to hydroboration in the presence of transition metals. As a result, a diverse range of γ-boronated amines with varied structures and functions has been readily obtained. Experimental mechanistic studies, density functional theory (DFT), and intrinsic bond orbital (IBO) calculations unveiled a hydroborane-promoted C-C bond cleavage and hydride-shift reaction pathway. The carbonyl group of the amide suppresses dehydrogenation between the free N-H and hydroborane. The lone pair on the nitrogen of the amide facilitates the cleavage of C-C bonds in cyclopropanes.

Regioselective Hydroboration of Unsymmetrical Internal Alkynes Catalyzed by a Cobalt Pincer-NHC Complex

Highly regioselective hydroboration of unsymmetrical internal alkynes remains a significant challenge for synthesizing valuable alkenylboronate esters. Herein, we describe an easily synthesizable pincer NHC-based Co complex as a catalyst for the cis-α selective hydroboration of unactivated internal alkynes and the cis-β selective hydroboration of activated internal alkynes with pinacolborane. The reaction showcases high chemo-, regio-, and stereoselectivity, and the catalyst displays high efficiency and very low loading under base-free reaction conditions. The reaction scope was demonstrated by alkynes having a variety of functional groups. The mechanistic studies suggest a feasible Co-boryl intermediate to explain the unusual regioselectivity.

Enantioconvergent Hydroboration of E/Z-Mixed Trisubstituted Alkenes

The lack of mode for chirality recognition makes it particularly challenging to carry out asymmetric transformations on E/Z-mixed minimally functionalized trisubstituted alkenes. Here, we report a catalytic enantioconvergent hydroboration of minimally functionalized trisubstituted E/Z-mixed alkenes to construct chiral organoboronic esters with excellent enantioselectivity using chiral radical cobalt catalyst. This C(sp3)-H borylation protocol showed good functional group tolerance and products could be converted to valuable compounds via C-B derivatizations. The mechanistic studies, which included control experiments, nonlinear effect experiments, deuterated labeling experiments, and X-ray diffraction, demonstrated that the favorable compatibility between the thermodynamically unfavorable isomerization and hydroboration was the key factor in achieving convergent transformation.

Catalytic Olefin Transpositions Facilitated by Ruthenium N,N,N-Pincer Complexes

In this report, we demonstrate olefin transposition/isomerization reactions catalyzed by a series of N,N,N-pincer (1,3-bis(2-pyridylimino)isoindoline) Ru-hydride complexes. The protocol proceeds at room temperature for most substrates, achieving excellent yields, regioselectivity, and diastereoselectivity in short reaction times. The air-stable Ru-chloride derivatives of these complexes exhibit comparable reactivity enabling benchtop setup and synthetic versatility. Furthermore, we demonstrate the potential for one-pot cascade sequences of the products derived from the transposition reactions.

Diphosphine Ligand-Enabled Nickel-Catalyzed Chelate-Assisted Inner-Selective Migratory Hydroarylation of Alkenes

The precise control of the regioselectivity in the transition metal-catalyzed migratory hydrofunctionalization of alkenes remains a big challenge. With a transient ketimine directing group, the nickel-catalyzed migratory β-selective hydroarylation and hydroalkenylation of alkenyl ketones has been realized with aryl boronic acids using alkyl halide as the mild hydride source for the first time. The key to this success is the use of a diphosphine ligand, which is capable of the generation of a Ni(II)-H species in the presence of alkyl bromide, and enabling the efficient migratory insertion of alkene into Ni(II)-H species and the sequent rapid chain walking process. The present approach diminishes organosilanes reductant, tolerates a wide array of complex functionalities with excellent regioselective control. Moreover, this catalytic system could also be applied to the migratory hydroarylation of alkenyl azahetereoarenes, thus providing a general approach for the preparation of 1,2-aryl heteroaryl motifs with wide potential applications in pharmaceutical discovery.

Highly Selective Nickel-Catalyzed Isomerization-Hydroboration of Alkenes Affords Terminal Functionalization at Remote C-H Position

We report herein the synthesis and characterization of nickel complexes supported by tridentate and bidentate phosphino(silyl) ancillary ligands, along with the successful application of these complexes as precatalysts for the hydroboration of terminal and internal alkenes using pinacolborane (HBPin). These reactions proceeded with low nickel loadings of 2.5-5 mol % in the absence of co-solvent, and in some cases at room temperature. Isomerization to afford exclusively the terminal hydroboration product was obtained across a range of internal alkenes, including tri- and tetra-substituted examples. This reactivity is unprecedented for nickel and offers a powerful means of achieving functionalization at a C-H position remote from the C=C double bond. Nickel-catalyzed deuteroboration experiments using DBPin support a mechanism involving 1,2-insertion of the alkene and subsequent chain-walking, which results in isotopic scrambling.

Construction of α-Halogenated Boronic Esters via Visible Light-Induced C-H Bromination

α-Halogenated boronic esters are versatile building blocks that can be diversified into a wide variety of polyfunctionalized molecules. However, their synthetic potential has been hampered by limited preparation methods. Herein, we report a visible light-induced C-H bromination reaction of readily available benzyl boronic esters. This method features high yields, mild conditions, simple operation, and good functional group tolerance. The analogous chlorides and iodides can be accessed via Finkelstein reaction. Synthesis of halogenated geminal diborons has also been demonstrated.

Synthesis and catalytic activity of well-defined Co(I) complexes based on NHC-phosphane pincer ligands

A new methodology for the preparation of Co(I)-NHC (NHC = N-heterocyclic carbene) complexes, namely, [Co(PCNHCP)(CO)2][Co(CO)4] (1) and [Co(PCNHCP)(CO)2]BF4 (2), has been developed (PCNHCP = 1,3-bis(2-(diphenylphosphanyl)ethyl)-imidazol-2-ylidene). Both complexes can be straightforwardly prepared by direct reaction of their parent imidazolium salts with the Co(0) complex Co2(CO)8. Complex 1 efficiently catalyses the reductive amination of furfural and levulinic acid employing silanes as reducing agents under mild conditions. Furfural has been converted into a variety of secondary and tertiary amines employing dimethyl carbonate as the solvent, while levulinic acid has been converted into pyrrolidines under solventless conditions. Dehydrocoupling of the silane to give polysilanes has been observed to occur as a side reaction of the hydrosilylation process.

Exploring the Effect of Pincer Rigidity on Oxidative Addition Reactions with Cobalt(I) Complexes

Cobalt complexes containing the 2,6-diaminopyridine-substituted PNP pincer (iPrPNMeNP = 2,6-(iPr2PNMe)2(C5H3N)) were synthesized. A combination of solid-state structures and investigation of the cobalt(I)/(II) redox potential established a relatively rigid and electron-donating chelating ligand as compared to iPrPNP (iPrPNP = 2,6-(iPr2PCH2)2(C5H3N)). Based on a buried volume analysis, the two pincer ligands are sterically indistinguishable. Nearly planar, diamagnetic, four-coordinate complexes were observed independent of the field strength (chloride, alkyl, aryl) of the fourth ligand completing the coordination sphere of the metal. Computational studies supported a higher barrier for C-H oxidative addition, largely a result of the increased rigidity of the pincer. The increased oxidative addition barrier resulted in stabilization of (iPrPNMeNP)Co(I) complexes, enabling the characterization of the cobalt boryl and the cobalt hydride dimer by X-ray crystallography. Moreover, (iPrPNMeNP)CoMe served as an efficient precatalyst for alkene hydroboration likely because of the reduced propensity to undergo oxidative addition, demonstrating that reactivity and catalytic performance can be tuned by rigidity of pincer ligands.

Remote Hydroamination of Disubstituted Alkenes by a Combination of Isomerization and Regioselective N-H Addition

Remote hydrofunctionalizations of alkenes incorporate functional groups distal to existing carbon-carbon double bonds. While remote carbonylations are well-known, remote hydrofunctionalizations are most common for addition of relatively nonpolar B-H, Si-H, and C-H bonds with alkenes. We report a system for the remote hydroamination of disubstituted alkenes to functionalize an alkyl chain selectively at the subterminal, unactivated, methylene position. Critical to the high regioselectivity and reaction rates are the electronic properties of the substituent on the amine and the development of the ligand DIP-Ad-SEGPHOS by evaluating the steric and electronic effects of ligand modules on reactivity and selectivity. The remote hydroamination is compatible with a broad scope of alkenes and aminopyridines and enables the regioconvergent synthesis of amines from an isomeric mixture of alkenes. The products can be derivatized by nucleophilic aromatic substitution on the amino substituent with a variety of nucleophiles.

Hydrido-Cobalt Complexes for the Chemo- and Regioselective 1,2-Silylative Dearomatization of N-Heteroarenes

We describe an efficient regio- and chemoselective dearomatization of N-heteroarenes using hydrido-cobalt catalysts. Reactions were performed under mild conditions on a wide range of N-heteroarenes leading exclusively to the silyl-1,2-dihydroheteroarene. Various quinolines and pyridines bearing electron-donating and electron-withdrawing substituents are compatible with this methodology. DFT calculations, NMR spectroscopic studies, and X-ray diffraction analysis underlined the importance of a second silane for the final step of the reaction.

Rhodium-Catalyzed Remote Borylation of Alkynes and Vinylboronates

Remote functionalization involving a fascinating chain-walking process has emerged as a powerful strategy for the rapid access to value-added functional molecules from readily available feedstocks. However, the scope of current methods is predominantly limited to mono- and di-substituted alkenes. The remote functionalization of multi- and heteroatom-substituted alkenes is challenging, and the use of alkynes in the chain walking is unexplored. We herein report a rhodium catalyzed remote borylation of internal alkynes, offering an unprecedented reaction mode of alkynes for the preparation of synthetically valuable 1,n-diboronates. The regioselective distal migratory hydroboration of sterically hindered tri- and tetra-substituted vinylboronates is also demonstrated to furnish various multi-boronic esters. Synthetic utilities are highlighted through the selective manipulation of the two boryl groups in products such as the regioselective cross coupling, oxidation, and amination.

Cobalt-Catalyzed Regioselective 1,2-Hydroboration of N-Heteroarenes

Regioselective hydroboration of pyridines to 1,2-dihydropyridines remains a significant challenge for the synthesis of valuable nitrogenous bioactive molecules. Herein, we report a base free ligand-controlled cobalt-catalyzed 1,2-hydroboration of pyridines and quinolines with very low catalyst loading under neat reaction conditions. The choice of sterically demanding N-heterocyclic ligands led to the 1,2-regioselectivity and the scope was demonstrated by the N-heterocycles having a variety of functional groups. The preliminary mechanistic studies corroborate that the two ligands followed a distinct catalytic cycle with Co(I) as an active species.

Ligand-Controlled NiH-Catalyzed Regiodivergent Chain-Walking Hydroalkylation of Alkenes

A NiH-catalyzed migratory hydroalkylation of alkenyl amines with predictable and switchable regioselectivity is reported. By utilizing a ligand-controlled, directing group-assisted strategy, various alkyl units are site-selectively installed at inert sp³ C-H sites far away from the original C=C bonds. A range of structurally diverse α- and β-branched protected amines are conveniently synthesized via stabilization of 5- and 6-membered nickelacycles respectively. This method exhibits broad scope and high functional group tolerance, and can be applied to late-stage modification of medicinally relevant molecules.

Development of a dimensionless and dynamic model of the three-phase trickle bed reactor in light naphtha isomerization process: effects of axial mass dispersion and liquid-solid mass transfer on isomers concentration

This study develops a general dimensionless model for a three-phase trickle bed reactor in the light naphtha isomerization process. The simulations are accomplished to study its conduct. The model brings up a one-dimensional axial dispersed flow to characterize dispersity and liquid-solid mass transfer in the forms of dimensionless Peclet and mass Stanton numbers under adiabatic conditions. It considers the essential reactions extant in the isomerization process comprising isomerization, hydrogenation, and hydrocracking reactions applying a precise approach of dimensionless kinetic equations and rate constants. The Crank–Nicolson method and a nonstandard finite difference approach are utilized for large systems of time-spatial PDEs to resolve the dynamic reactor model with MATLAB software. The aim is to elucidate how these large systems of PDEs and nonlinear ODEs can be solved with a comprehensive computation in the form of physical dimensionless numbers. The isomers compositions estimated with the suggested model are in corroboration simulation results obtained by empirical information. The dynamics are evaluated to consider the system conduct with a variation in the hydrogen concentration of the feedstock.

Enantioselective Cobalt-Catalyzed Hydroboration of Ketone-Derived Silyl Enol Ethers

Catalytic asymmetric hydroboration of alkenes is a powerful tool for the synthesis of natural products, agrochemicals, and pharmaceuticals via the versatile transformations of chiral alkyl boronic esters. However, the scope of available alkenes is limited to styrenes, activated alkenes, and compounds with directing groups. The catalytic enantioselective hydroboration of heteroatom-substituted alkenes is rarely explored and those catalyzed by earth-abundant metals are yet to be reported. Herein, we report a cobalt-catalyzed asymmetric hydroboration of ketone-derived silyl enol ethers and provide a convenient approach to access valuable enantiopure β-hydroxy boronic esters. This protocol features mild reaction conditions, a broad substrate scope, and excellent enantioselectivities (up to 99 % ee). This approach was applied in the successful synthesis of salmeterol and albuterol, demonstrating its potential to streamline complex molecule synthesis.

Solvent-free hydroboration of alkynes catalyzed by an NHC-cobalt complex

A new cobalt complex bearing a bulky N-heterocyclic carbene (NHC) ligand is described as a pre-catalyst for alkyne hydroboration. The proposed catalytic system, synthesized using easily accessible reagents, allowed obtaining a series of mono- and dialkenylboranes in solvent-free conditions with excellent efficiency and selectivity. The results have been compared to those obtained in the presence of the same cobalt complex containing smaller NHC ligands and those achieved for the catalytic system based on a CoCl2 - NHC precursor.

Remote Site-Selective Asymmetric Protoboration of Unactivated Alkenes Enabled by Bimetallic Relay Catalysis

A remote C(sp³ )-H bond asymmetric borylation of unactivated alkenes was achieved by bimetallic relay catalysis. The reaction proceeded through reversible and consecutive β-H elimination/olefin insertion promoted by CoH species generated in situ, followed by copper-catalyzed asymmetric protoboration. The use of this synergistic Co/Cu catalysis protocol allowed the enantioselective protoboration of various unactivated terminal alkenes and internal alkenes, as well as an unrefined mixture of olefin isomers, at the distal less-reactive β-position to a functional group, leading to chiral organoboronates.

Synergistic Hydrocobaltation and Borylcobaltation Enable Regioselective Migratory Triborylation of Unactivated Alkenes

The structural diversity of sp³ -triorganometallic reagents enhances their potentiality in the modular construction of molecular complexity in chemical synthesis. Despite significant achievements on the preparation of sp³ 1,1,1- and 1,1,2-triorganometallic B,B,B-reagents, catalytic approaches that enable the installation of multiple boryl groups at skipped carbons of unactivated alkenes still remain elusive. Herein, we report a cobalt-catalyzed selective triborylation reaction of unactivated alkenes to access synthetically versatile 1,1,3-triborylalkanes. This triborylation protocol provides a general platform for regioselective trifunctionalization of unactivated alkenes, and its utility is highlighted by the synthesis of various value-added chemicals from readily accessible unactivated alkenes. Mechanistic studies, including deuterium-labelling experiments and evaluation of potential reactive intermediates, provide insight into the experimentally observed chemo- and regioselectivity.

Fragmentation and transferability in Hirshfeld atom refinement

Hirshfeld atom refinement (HAR) is one of the most effective methods for obtaining accurate structural parameters for hydrogen atoms from X-ray diffraction data. Unfortunately, it is also relatively computationally expensive, especially for larger molecules due to wavefunction calculations. Here, a fragmentation approach has been tested as a remedy for this problem. It gives an order of magnitude improvement in computation time for larger organic systems and is a few times faster for metal-organic systems at the cost of only minor differences in the calculated structural parameters when compared with the original HAR calculations. Fragmentation was also applied to polymeric and disordered systems where it provides a natural solution to problems that arise when HAR is applied. The concept of fragmentation is closely related to the transferable aspherical atom model (TAAM) and allows insight into possible ways to improve TAAM. Hybrid approaches combining fragmentation with the transfer of atomic densities between chemically similar atoms have been tested. An efficient handling of intermolecular interactions was also introduced for calculations involving fragmentation. When applied in fragHAR (a fragmentation approach for polypeptides) as a replacement for the original approach, it allowed for more efficient calculations. All of the calculations were performed with a locally modified version of Olex2 combined with a development version of discamb2tsc and ORCA. Care was taken to efficiently use the power of multicore processors by simple implementation of load-balancing, which was found to be very important for lowering computational time.

Contra-thermodynamic Olefin Isomerization by Chain-Walking Hydroboration and Dehydroboration

We report a dehydroboration process that can be coupled with chain-walking hydroboration to create a one-pot, contra-thermodynamic, short- or long-range isomerization of internal olefins to terminal olefins. This dehydroboration occurs by a sequence comprising activation with a nucleophile, iodination, and base-promoted elimination. The isomerization proceeds at room temperature without the need for a fluoride base, and the substrate scope of this isomerization is expanded over those of previous isomerizations we have reported with silanes.

The transition metal-catalysed hydroboration reaction

This review covers the development of the transition metal-catalysed hydroboration reaction, from its beginnings in the 1980s to more recent developments including earth-abundant catalysts and an ever-expanding array of substrates.

Ligand-controlled cobalt-catalyzed remote hydroboration and alkene isomerization of allylic siloxanes

The Co-catalyzed remote hydroboration and alkene isomerization of allylic siloxanes were realized by a ligand-controlled strategy. The remote hydroboration with dcype provided borylethers, while xantphos favored the formation of silyl enol ethers.

First-Row d-Block Element-Catalyzed Carbon-Boron Bond Formation and Related Processes

Organoboron reagents represent a unique class of compounds because of their utility in modern synthetic organic chemistry, often affording unprecedented reactivity. The transformation of the carbon-boron bond into a carbon-X (X = C, N, and O) bond in a stereocontrolled fashion has become invaluable in medicinal chemistry, agrochemistry, and natural products chemistry as well as materials science. Over the past decade, first-row d-block transition metals have become increasingly widely used as catalysts for the formation of a carbon-boron bond, a transformation traditionally catalyzed by expensive precious metals. This recent focus on alternative transition metals has enabled growth in fundamental methods in organoboron chemistry. This review surveys the current state-of-the-art in the use of first-row d-block element-based catalysts for the formation of carbon-boron bonds.

Cobalt-Catalyzed Remote Hydroboration of Alkenyl Amines

We here present a generally applicable cobalt-catalyzed remote hydroboration of alkenyl amines, providing a practical strategy for the preparation of borylamines and aminoalcohols. This method shows broad substrate scope and good functional group tolerance, tolerating a series of alkenyl amines, including alkyl-alkyl amines, alkyl-aryl amines, aryl-aryl amines, and amides. Of note, this protocol is also compatible with a variety of natural products and drug derivatives. Preliminary mechanistic studies suggest that this transformation involves an iterative chain walking and hydroboration sequence.

γ-Selective C(sp3)-H amination via controlled migratory hydroamination

Remote functionalization of alkenes via chain walking has generally been limited to C(sp3)-H bonds α and β to polar-functional units, while γ-C(sp3)-H functionalization through controlled alkene transposition is a longstanding challenge. Herein, we describe NiH-catalyzed migratory formal hydroamination of alkenyl amides achieved via chelation-assisted control, whereby various amino groups are installed at the γ-position of aliphatic chains. By tuning olefin isomerization and migratory hydroamination through ligand and directing group optimization, γ-selective amination can be achieved via stabilization of a 6-membered nickellacycle by an 8-aminoquinoline directing group and subsequent interception by an aminating reagent. A range of amines can be installed at the γ-C(sp3)-H bond of unactivated alkenes with varying alkyl chain lengths, enabling late-stage access to value-added γ-aminated products. Moreover, by employing picolinamide-coupled alkene substrates, this approach is further extended to δ-selective amination. The chain-walking mechanism and pathway selectivity are investigated by experimental and computational methods.

Low-Valent Tungsten Catalysis Enables Site-Selective Isomerization-Hydroboration of Unactivated Alkenes

A tungsten-catalyzed hydroboration of unactivated alkenes at distal C(sp3)-H bonds aided by native directing groups is described herein. The method is characterized by its simplicity, exquisite regio- and chemoselectivity, and wide substrate scope, offering a complementary site-selectivity pattern to other metal-catalyzed borylation reactions and chain-walking protocols.

Site-Fixed Hydroboration of Terminal and Internal Alkenes using BX3 /i Pr2 NEt*

An unprecedented and general hydroboration of alkenes with BX₃ (X=Br, Cl) as the boration reagent in the presence of ⁱ Pr₂ NEt is reported. The addition of ⁱ Pr₂ NEt not only suppresses alkene polymerization and haloboration side reactions but also provides an "H" source for hydroboration. More importantly, the site-fixed installation of a boryl group at the original position of the internal double bond is readily achieved in contrast to conventional transition-metal-catalyzed hydroboration processes. Further application to the synthesis of 1,n-diborylalkanes (n=3-10) is also demonstrated. Preliminary mechanistic studies reveal a major reaction pathway that involves radical species and operates through a frustrated Lewis pair type single-electron-transfer mechanism.

Metal-free reduction of unsaturated carbonyls, quinones, and pyridinium salts with tetrahydroxydiboron/water

A series of unsaturated carbonyls, quinones, and pyridinium salts have been effectively reduced to the corresponding saturated carbonyls, dihydroxybenzenes, and hydropyridines in moderate to high yields with tetrahydroxydiboron/water as a mild, convenient, and metal-free reduction system. Deuterium-labeling experiments have revealed this protocol to be an exclusive transfer hydrogenation process from water.

α-Hydroxy boron-enabled regioselective access to bifunctional halo-boryl alicyclic ethers and α-halo borons

α-Hydroxy borons are an underutilized class of compounds and their only previous application involved oxidation into acylborons. Herein, we describe the synthesis of functionalized olefinic α-hydroxy borons and their utility to enable a novel and regioselective route to hitherto unknown bifunctional halo-boryl tetrahydrofurans/tetrahydropyrans and α-halo MIDA boronates. The orthogonally functionalized alicyclic ethers provided a building block-based approach for diversification of the tetrahydrofuran core.

Iron Catalyzed Double Bond Isomerization: Evidence for an FeI /FeIII Catalytic Cycle

Iron-catalyzed isomerization of alkenes is reported using an iron(II) β-diketiminate pre-catalyst. The reaction proceeds with a catalytic amount of a hydride source, such as pinacol borane (HBpin) or ammonia borane (H3 N⋅BH3 ). Reactivity with both allyl arenes and aliphatic alkenes has been studied. The catalytic mechanism was investigated by a variety of means, including deuteration studies, Density Functional Theory (DFT) and Electron Paramagnetic Resonance (EPR) spectroscopy. The data obtained support a pre-catalyst activation step that gives access to an η2 -coordinated alkene FeI complex, followed by oxidative addition of the alkene to give an FeIII intermediate, which then undergoes reductive elimination to allow release of the isomerization product.