Synthesis Of Tri Research Articles

Hybrid anionic block copolymerization: From organocatalysis‐streamlined crossover to internally microphase‐separated aggregates

AbstractPolyolefin‐b‐poly(ethylene oxide) (PEO) represents the most widely investigated amphiphilic block copolymers. So far, one‐pot continuous synthesis of such hybrid block copolymers has only been fulfilled by anionic polymerization through sequential addition of vinyl monomers and ethylene oxide (EO). It still remains challenging to achieve altogether high block efficiency, high polymerization efficiency, and high molar mass for PEO. Here, we report a one‐pot hybrid block copolymerization approach to polyisoprene/polystyrene(PI/PS)‐b‐PEO, in which PI/PS are formed by sBuLi‐initiated anionic vinyl‐addition polymerization, then in situ employed as macroinitiators for the anionic ring‐opening polymerization (ROP) of EO aided by an organic Lewis pair. The cooperative (dual‐ion‐complexing) catalytic effect of organobase and triethylborane is proven, for the first time, effective for lithium alkoxide initiator system, allowing to achieve at room temperature high ROP activity (complete EO conversion and PEO of 3–64 kg/mol reached in 1–6 h), narrow molar mass distribution, controlled block lengths and composition. Density functional theory calculation shows that phosphazene bases are particularly effective, compared with N‐heterocyclic bases, for complexing with Li+ and enhancing the nucleophilicity of oxyanion. The rate of ROP is also affected by Li+‐induced aggregation of the chain‐end ion pairs, which though can be offset by adequate catalyst loadings. The versatility of this approach is further demonstrated in the one‐pot synthesis of tri‐/tetrablock ter‐/quaterpolymers constituted by PI, PS, PEO, and poly(propylene oxide). Of great interest, PS‐b‐PI‐b‐PEO triblock terpolymer with a specific composition is found to form internally microphase‐separated micellar aggregates when dispersed in water.

Phosphorus fluoride exchange: Multidimensional catalytic click chemistry from phosphorus connective hubs

Phosphorus Fluoride Exchange (PFEx) represents a cutting-edge advancement in catalytic click-reaction technology. Drawing inspiration from Nature's phosphate connectors, PFEx facilitates the reliable coupling of P(V)-F loaded hubs with aryl alcohols, alkyl alcohols, and amines to produce stable, multidimensional P(V)-O and P(V)-N linked products. The rate of P-F exchange is significantly enhanced by Lewis amine base catalysis, such as 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD). PFEx substrates containing multiple P-F bonds are capable of selective, serial exchange reactions via judicious catalyst selection. In fewer than four synthetic steps, controlled projections can be deliberately incorporated along three of the four tetrahedral axes departing from the P(V) central hub, thus taking full advantage of the potential for generating three-dimensional diversity. Furthermore, late-stage functionalization of drugs and drug fragments can be achieved with the polyvalent PFEx hub, hexafluorocyclotriphosphazene (HFP), as has been demonstrated in prior research.

Synthesis of tri- and tetrasubstituted stereocentres by nickel-catalysed enantioselective olefin cross-couplings

Synthesis of tri- and tetrasubstituted stereocentres by nickel-catalysed enantioselective olefin cross-couplings

Synthesis of tri, tetra, and hexa-palmitate polyol esters from Malaysian saturated palm fatty acid distillate for biolubricant production

Synthesis of tri, tetra, and hexa-palmitate polyol esters from Malaysian saturated palm fatty acid distillate for biolubricant production

Synthesis of Tri- and Tetra- Phenyl Substituted 1H-imidazoles in the Presence of Chitin and Pectin as Natural Catalyst

Introduction: Chitin and pectin are important natural polymers which are used as a natural catalyst for the synthesis of tri- and tetra- phenyl substituted 1H-imidazoles. Material and Methods: The reaction of benzil and aromatic aldehydes with ammonium acetate in the presence of chitin produces 2,4,5-triphenyl-1H-imidazoles and the reaction of benzil, aromatic aldehydes and aniline derivatives with ammonium acetate in the presence of pectin produces 1,2,4,5- tetraphenyl-1H-imidazoles, respectively. Results: The results show that the synthesis of 2,4,5-triphenyl-1H-imidazoles and 1,2,4,5-tetraphenyl- 1H-imidazoles can be catalyzed by chitin and pectin in an effective route, respectively. All synthesized compounds are in good agreement with previously reported compounds. Conclusion: In conclusion, an efficient methodology has been carried out to generate 2,4,5-triphenyl- 1H-imidazoles and 1,2,4,5-tetraphenyl-1H-imidazoles, by using non-toxic, cheap and in available catalysis (chitin and pectin).

Electrooxidative dearomatization of biaryls: synthesis of tri- and difluoromethylated spiro[5.5]trienones.

Radical spirocyclization via dearomatization has emerged as an attractive strategy for the rapid synthesis of structurally diverse spiro molecules. We report the use of electrochemistry to perform an oxidative dearomatization of biaryls leading to tri- and difluoromethylated spiro[5.5]trienones in a user friendly undivided cell set-up and a constant current mode. The catalyst- and chemical oxidant-free dearomatization procedure features ample scope, and employs electricity as the green and sole oxidant.

Synthesis of Tri(4-formylphenyl) Phosphonate Derivatives as Recyclable Triple-Equivalent Supports of Peptide Synthesis.

To seek the novel application of organophosphorus compounds, the designed tri(4-formylphenyl) phosphonate (TFP) derivatives were successfully synthesized herein, which were used as C-terminal protecting groups of amino acid or greener triple-equivalent supports in liquid-phase peptide synthesis (LPPS). Through the support-aided precipitation effect of TFP derivatives, the peptide intermediates during peptide synthesis were separated and collected via rapid precipitation and facile filtration without chromatographic purification. Furthermore, the TFP derivative support can be directly recycled for reuse without further regeneration after being sheared from the target peptide.

Synthesis of Tri‐ and Difluoromethoxylated Compounds by Visible‐Light Photoredox Catalysis

AbstractTrifluoromethoxy (OCF3) and difluoromethoxy (OCF2H) groups are fluorinated structural motifs that exhibit unique physicochemical characteristics. Incorporation of these substituents into organic molecules is a highly desirable approach used in medicinal chemistry and drug discovery processes to alter the properties of a parent compound. Recently, tri‐ and difluoromethyl ethers have received increasing attention and several innovative strategies to access these valuable functional groups have been developed. The focus of this Minireview is the use of visible‐light photoredox catalysis in the synthesis of tri‐ and difluoromethyl ethers. Recent photocatalytic strategies for the formation of O−CF3, C−OCF3, O−CF2H, and C−OCF2H bonds as well as other transformations leading to the construction of ORF groups are discussed herein.

Synthesis of Tri- and Difluoromethoxylated Compounds by Visible-Light Photoredox Catalysis.

Trifluoromethoxy (OCF3 ) and difluoromethoxy (OCF2 H) groups are fluorinated structural motifs that exhibit unique physicochemical characteristics. Incorporation of these substituents into organic molecules is a highly desirable approach used in medicinal chemistry and drug discovery processes to alter the properties of a parent compound. Recently, tri- and difluoromethyl ethers have received increasing attention and several innovative strategies to access these valuable functional groups have been developed. The focus of this Minireview is the use of visible-light photoredox catalysis in the synthesis of tri- and difluoromethyl ethers. Recent photocatalytic strategies for the formation of O-CF3 , C-OCF3, O-CF2 H, and C-OCF2 H bonds as well as other transformations leading to the construction of ORF groups are discussed herein.

Synthesis of tri(di)fluoroethylanilines via copper-catalyzed coupling reaction of tri(di)fluoroethylamine with (hetero)aromatic bromides.

We have realized the first Ullmann type coupling reaction of tri(di)fluoroethylamine with (hetero)aromatic bromides, employing 5-20 mol% Cu2O and an oxalamide ligand [N-(2,4,6-trimethoxyphenyl)acetamide]. This efficient and practical method has the following features: (i) avoids the use of an expensive catalyst; (ii) does not require anhydrous solvent and strict air extrusion; (iii) uses bench stable and inexpensive (hetero)aromatic bromides; (iv) is suitable for the synthesis of fluoroalkylated hetero-aromatic substrates; (v) is suitable for gram-scale synthesis. This work also shows the "negative fluorine effect" for the alkylamines in the copper catalysed coupling reactions.

Intramolecular hydroalkoxylation of syn- and anti-1-R-2-arylhex-4-en-1-ols. Efficient stereoselective synthesis of tri- and tetrasubstituted tetrahydrofurans

Reactions of syn- and anti-4-(4-bromophenyl)-2-methylnon-1-en-5-ols and 3-(4-bromophenyl)-5- methyl-1-phenylhex-5-en-2-ols with trifluoromethanesulfonic acid and salicylaldehyde derivatives in the presence of Et2O · BF3 (Prins reaction) or with salicylaldehydes in the presence of trimethyl orthoformate and p-toluenesulfonic acid stereoselectively afforded tri- and tetrasubstituted tetrahydrofurans with one or two fused heterocycles and various functional groups (COOEt, Br, MeC=CH2). The reactivity of the synthesized compounds toward thiophen-2-ylboronic acid in the Suzuki reaction was studied, and hydrolysis and reduction (LiAlH4) of the ester group therein gave the corresponding carboxylic acids and alcohols. One of the obtained tetrahydrofuran derivatives was converted into amide, aldehyde, and aldehyde oxime. Stereochemical configuration of substituents was retained in all chemical transformations.

Stereoselective Cyclopropanation of (–)-Levoglucosenone Derivatives Using Sulfonium and Sulfoxonium Ylides

The synthesis of tri- and tetrasubstituted cyclopropanes from 3-aryl-substituted levoglucosenones (LGO) has been developed. In contrast to the unstabilised ylide dimethylsulfonium methylide which gives epoxides from LGO via 1,2-addition, we have found that the soft nucleophile dimethylsulfoxonium methylide affords cyclopropanes in moderate yields from LGO and in excellent yields and stereoselectivity with 3-aryl LGO derivatives. The use of 1,1,3,3-tetramethylguanidine as base in DMSO to generate the ylide provided the best yields and shortest reaction times. Ester stabilised sulfonium ylides could also be used to generate tetrasubstituted cyclopropane derivatives. One of the products was converted into a cyclopropyl lactone via Baeyer–Villiger oxidation to demonstrate the utility of applying cyclopropanation chemistry to LGO.

Condensation of СН-acids with cis-1,4-dichlorobut-2-ene

Synthesis of tri- and five-membered carboxylates are discussed. Microwave irradiation has been shown to stimulate the condensation of СН-acids with allyl chlorides. The selectivity of formation of target products was depending on the CH-acid structure. Structures of the isolated compounds have been confirmed by 1Н and 13С NMR spectroscopy and chromato–mass spectrometry data.

Consecutive three- and four-component coupling-Bagley-Bohlmann-Rahtz syntheses of tri- and tetrasubstituted pyridines

AbstractThe concatenation of the modified Sonogashira alkynone synthesis and the Bagley-Bohlmann-Rahtz pyridine synthesis gives novel consecutive three- and four-component coupling-Bagley-Bohlmann-Rahtz (cBBR) syntheses of tri- and tetrasubstituted pyridines in a one-pot fashion. With these processes 15 differently substituted 3-ethoxycarbonyl 2-methylpyridines can be readily obtained in modest to moderate yields.

Synthesis of tri- and tetrasaccharide glycosides of (4S)-4-hydroxy-d-proline relevant to the cell wall O-glycans of green alga Chlamydomonas reinhardtii

The synthesis of tri- and tetrasaccharide glycosides of (4S)-4-hydroxy-d-proline 1 and 2 with unusual glycan motifs has been achieved efficiently. The assembly of the synthetically challenging 1,2-cis linked arabino- and galactofuranoside frameworks within the targets was realized by the use of a 2-quinolinecarbonyl-assisted 1,2-cis furanosylation approach.

Ce(SO4)2⋅4H2O as a highly efficient catalyst for the one-pot synthesis of tri- and tetra-substituted imidazoles under solvent-free conditions

A solvent-free one-pot convenient synthetic route for rapid synthesis of various tri- and tetra-substituted imidazole derivatives has been developed using Ce(SO4)2⋅4H2O as an efficient catalyst with high catalytic activity in the three-component reaction (3-CR) of benzil or benzoin, aromatic aldehydes, and ammonium acetate, as well as in the four-component reaction (4-CR) of benzil, aryl aldehydes, benzyl amine, and ammonium acetate. These protocols provide an excellent and versatile synthetic scaffold for construct of various heterocycles containing imidazole as a core frame.

Synthesis of tri-, tetra-, and pentacarbonyl derivatives via ozonolysis of 1,4-dienes and cyclization to polyaromatic systems.

The aim of this work was the synthesis of polyaromatic systems by cyclization of β-polycarbonyls. Useful synthons for β-polycarbonyl derivatives are branched 1,4-dienes generated by cobalt-catalyzed hydrovinylation of terminal alkenes and 2,3-dimethyl-1,3-butadiene. Thus, a series of tri-, tetra-, and pentacarbonyl synthons was successfully synthesized. Subsequently, these synthons were examined in an ozonolysis/cyclization reaction sequence. Polyaromatic derivatives were obtained in good yields and the method was applied in the synthesis of the natural product Kwanzoquinone A.

Synthesis of tri- and tetra-mannosides based on sequential one-pot three-component glycosylation reactions

Synthesis of tri- and tetra-mannosides based on sequential one-pot three-component glycosylation reactions

Multivalent (Nitrilotriacetic Acid)-End-Functionalized Polystyrenes by ATRP and Their Self-Assembly

The synthesis of tri-(nitrilotriacetic acid) (NTA)-end-functionalized polystyrenes using an initiator containing tert-butyl protected NTA moieties, by atom transfer radical polymerization (ATRP) of styrene is described. First, a suitable ATRP initiator is prepared and subsequently characterized by 1H and 13C NMR spectroscopy, gel-permeation chromatography (GPC), and matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectro­scopy. The structures of the tri-NTA-end-functionalized polystyrenes (tri-NTA-PS) are confirmed by 1H and 13C NMR spectroscopy. Tri-NTA-PS itself produces self-assembled spherical aggregates with ≈40–60 nm diameters in water/THF, whereas nickel-complexed tri-NTA-PS produces spherical core–shell hybrid aggregates with ≈90–115 nm diameters with His-tagged GFP in water/DMF (DMF 4 vol%), as confirmed by transmission electron microscopy and dynamic light scattering measurements.

Synthesis of Tri- and Tetrasubstituted Pyrazoles via Ru(II) Catalysis: Intramolecular Aerobic Oxidative C–N Coupling

An unprecedented ruthenium(II)-catalyzed intramolecular oxidative C-N coupling method has been developed for the facile synthesis of a variety of synthetically challenging tri- and tetrasubstituted pyrazoles. Dioxygen gas is employed as the oxidant in this transformation. The reaction demonstrates excellent reactivity, functional group tolerance, and high yields.