Monosubstitution Reactions Research Articles

The syntheses of 2-hydroxybenzothiazole substituted cyclotriphosphazenes: Spectroscopic characterizations

The nucleophilic substitution reactions of mono- and bis-spiro-2,2’-dioxybiphenyl cyclotriphosphazenes (1a and 1b) with 2-hydroxybenzothiazole (2) were performed in the presence of metallic sodium in THF. Two novel 2-oxybenzothiazole-substituted spiro-2,2′-dioxybiphenyl cyclotriphosphazene derivatives (3a and 3b) were obtained from these reactions. Both compounds (3a, 3b) have been characterized by elemental analysis as well as by 1H, 13C and 31P NMR spectroscopy. Compounds 3a and 3b are reported for the first time in this study.

MTHPP monoacetic ester: unexpected formation, zinc metalation, thermal and photophysical properties

In the current investigation we report an unexpected methyl esterification occurred during the coupling reaction of mTHPP monoacetic acid 2 with 3-amino-1,2,4-triazole in the presence of HBTU/DIPEA. The mechanism of this unexpected methyl esterification was studied, and the structure of the formed methyl ester 5 was confirmed by the means of 1H, 13C NMR in addition to (MALDI-TOF and ESI-HRMS) spectrometry. The formation of 5 during the coupling reaction was also chemically supported by an alternative synthetic method involving a direct monosubstitution reaction of mTHPP 1 with methyl bromoacetate. We also investigated the metalation of 5 with zinc and studied the thermal properties along with differential scanning calorimetry (DSC) of the zinc porphyrin 6. The photophysical properties of porphyrin methyl ester 5 and its zinc complex 6 were also investigated.Graphical

Influence of Polymer Topology on Gas Separation Membrane Performance of the Polymer of Intrinsic Microporosity PIM-Py

The polymer synthesis of 2,3,5,6-tetrafluoro-4-pyridinecarbonitrile-3,3,3′,3′-tetramethyl-1,1′-spirobisindane-5,5′,6,6′-tetrol copolymer, termed PIM-Py, was investigated under different solvent (dimethylformamide (DMF) and dimethylacetamide/dichlorobenzene) and temperature (65–160 °C) conditions to produce a range of topologically different polymer samples. Characterization of the polymers, particularly with proton NMR spectroscopy and multiple detector SEC analysis, indicated that, like PIM-1, the polymerizations proceeded with a degree of polymer chain branching. This is attributed to the occurrence of monosubstitution reactions, instead of disubstitution, which eventually leads to a significant proportion of colloidal network formation. However, all polymer samples remained soluble/dispersible in chloroform at the concentration required to cast self-standing films. This work reports the first examination of PIM-Py as a membrane for gas separation applications. The most structurally diverse PIM-Py samples produced films that exhibited selectivity/permeability balances in single gas permeation studies above the 2008 Robeson upper bound for the CO2/N2 gas pair. Indeed, a film cast from the highest colloidal network content sample surpassed the recently introduced 2019 CO2/N2 upper bound. After 143 days of aging, a 40 μm self-standing membrane still exhibited a single gas CO2 permeability of 4480 barrer and an ideal CO2/N2 selectivity of 45. The polymers produced in lower temperature reactions in DMF exhibited gas separation performances very similar to a structurally regular “normal” PIM-1 polymer, sitting on or around the 2008 Robeson upper bound line. Single gas permeation measurements to determine CO2/CH4 selectivity showed similar trends across the range of polymer samples, without generally reaching high selectivities as for the CO2/N2 pair. Mixed gas CO2/CH4 permeation measurements with aging were also completed for PIM-Py membranes, which indicated similar gas separation performance to a structurally regular PIM-1 polymer. This study would suggest that, like PIM-1, gas separation performance of PIM-Py is greatly influenced by the topological balance toward branched and network material within the polymer sample.

Nucleophilic substitution reactions of monofunctional nucleophilic reagents with cyclotriphosphazenes containing 2,2-dioxybiphenyl units.

The nucleophilic substitution reactions of mono- and bis-spiro-2,2′ -dioxybiphenyl cyclotriphosphazenes (3 and 4) with cyclopropanemethylamine (5) and aniline (6) were performed in the presence of trimethylamine in THF. Five novel cyclopropanemethylamino- and anilino-substituted spiro-2,2′ -dioxybiphenyl cyclotriphosphazene derivatives (7–11) were obtained from these reactions. The molecular structures of the new cyclotriphosphazene derivatives (7–11) were characterized by elemental analysis, MALDI-TOF MS, FT-IR, and NMR ( 31 P and 1 H) spectroscopies. The structure of the spiro-(2,2′ -dioxybiphenyl)-bis-(anilino)-cyclotriphosphazene (11) was also determined by single-crystal X-ray crystallography.

On the selectivity of silver mediated thiolate transfer and the crystal structure of an unprecedented thiolate chloride Argentate(I) anion

The reactivity of a series of fluorinated silver(I) thiolates (AgSRF) towards thiolation of dichloromethane by nucleophilic substitution in presence of bis(diphenylphosphane)methane (dppm) has been studied. Our results indicate that in the presence of an excess of CH2Cl2 the thiolate phosphine silver derivatives are capable of exchange thiolate and chloride to form, in different proportions, the correspondent chloromethylthioether (CH2Cl(SRF)) a or methyldithioether (CH2(SRF)2) b with the fluorinated SRF groups: SC6F4H 1, SC6H4(CF3)-2 2, SC6H3F2-3,4 3, SC6H3F2-2,4 4, SC6H3F2-3,5 5 and SC6H4F-2 6. Despite the kinetically preferred monosubstitution reaction, some of the thiolate derivatives tend to form selectively the disubstitution products, indicating a non-innocent role of the silver center in the formation of the product. Furthermore, we have isolated and structurally characterized, by X-ray diffraction, an ionic compound [Ag3(μ3-Cl)2(μ-Ph2PCH2PPh2)3][AgCl(SC6F4H)] that could be an intermediary product in the chloride-thiolate exchange reactions.

Substitution reactions of mono-, di- and tri-thiocarbonato complexes of iron

The photolytic reactions of iron thiocarbonato complexes CpFe(CO)2SC(Y)Y′R [Y=Y′=O; R=2-C6H4Cl (1), 4-C6H4Cl (2); Y=S, Y′=O; R=C6H4F (3), Y=Y′=S; R=Ph (4)] with EPh3 (E=P, As, Sb) are performed. Monosubstituted complexes of the general formula CpFe(CO)(EPh3)SC(Y)Y′R [Y=Y′=O; R=2-C6H4Cl (5), 4-C6H4Cl (6); Y=S, Y′=O; R=C6H4F (7), Y=Y′=S; R=Ph (8); E=P (a), As (b), Sb (c)] have been isolated and characterized by spectroscopic analysis (UV–Vis, IR, 1H, 31P NMR) and elemental analysis. The molecular structures of CpFe(CO)(PPh3)SCO2-2-C6H4Cl (5a) and its dicarbonyl parent CpFe(CO)2SCO2-2-C6H4Cl (1) have been determined by single crystal X-ray crystallographic studies.

Effective, transition metal free and selective C–F activation under mild conditions

A simple and effective aromatic nucleophilic monosubstitution reaction for the synthesis of aromatic amines via selective C–F bond cleavage of various fluoroarenes with primary and secondary aromatic amines is demonstrated.

P.1.g.059 A novel analogue of fragment of vasopressin causes decrease of depression components in rats after neonatal intranasal injection

(E)- and (Z)-2,3-dibromopropenoates were found to be able to react with Bu3SnXR1 (X = O,S; R1 = alkyl, aryl) in NMP solution at 20 °C in the presence of Pd(PPh3)4 to give the corresponding 3-alkoxy, 3-arylthio and 3-alkylthio substituted products. Under similar conditions methyl (E)- and (Z)-3-bromopropenoate, methyl (Z)-3-iodo-2-octenoate, 3-alkoxycarbonyl substituted (cyclo)alkenyl triflates as well as methyl 3-bromopropiolate, were converted into the corresponding 3-methylthio or 3-phenylthio substituted products when compounds Bu3SnSR1 (R1  Me, Ph) were used as nucleophiles. On the contrary, 2-bromo substituted α,β-unsaturated esters or lactones as well as a 2-substituted alkyl 3-bromopropenoate did not under Pd-mediated substitution reactions by treatment with Bu3SnOR1 and 3-substituted (E)-2,3-dibromopropenoates, and 3-substituted (Z)-3-iodopropenoates afforded the corresponding α,β-acetylenic esters, when reacted with Bu3SnOR1 in the presence of Pd(PPh3)4. A selective monosubstitution reaction also occurred when 1,2-dibromobenzene, was reacted with PhSSnBu3 in toluene in the presence of Pd(PPh3)4. Finally, compounds (E)- and (Z)-22a, which were prepared by Pd-mediated CS bond forming reactions, were used as direct precursors to some natural carboxyamides.

P.1.g.058 “Structure–neurotropic activity” relationship in novel 3-substituted derivatives of 1,4-benzodiazepine

(E)- and (Z)-2,3-dibromopropenoates were found to be able to react with Bu3SnXR1 (X = O,S; R1 = alkyl, aryl) in NMP solution at 20 °C in the presence of Pd(PPh3)4 to give the corresponding 3-alkoxy, 3-arylthio and 3-alkylthio substituted products. Under similar conditions methyl (E)- and (Z)-3-bromopropenoate, methyl (Z)-3-iodo-2-octenoate, 3-alkoxycarbonyl substituted (cyclo)alkenyl triflates as well as methyl 3-bromopropiolate, were converted into the corresponding 3-methylthio or 3-phenylthio substituted products when compounds Bu3SnSR1 (R1  Me, Ph) were used as nucleophiles. On the contrary, 2-bromo substituted α,β-unsaturated esters or lactones as well as a 2-substituted alkyl 3-bromopropenoate did not under Pd-mediated substitution reactions by treatment with Bu3SnOR1 and 3-substituted (E)-2,3-dibromopropenoates, and 3-substituted (Z)-3-iodopropenoates afforded the corresponding α,β-acetylenic esters, when reacted with Bu3SnOR1 in the presence of Pd(PPh3)4. A selective monosubstitution reaction also occurred when 1,2-dibromobenzene, was reacted with PhSSnBu3 in toluene in the presence of Pd(PPh3)4. Finally, compounds (E)- and (Z)-22a, which were prepared by Pd-mediated CS bond forming reactions, were used as direct precursors to some natural carboxyamides.

Selective C4–F bond cleavage of pentafluorobenzene: synthesis of N-tetrafluoroarylated heterocyclic compounds

Abstract A simple aromatic nucleophilic monosubstitution reaction for the synthesis of N-tetrafluoroarylated heterocyclic compounds via selective C4–F bond cleavage of pentafluorobenzene with N–H containing heterocycles is demonstrated. This method is highly tolerant of a wide range of substrates to give the corresponding products in moderate to good yields. Additionally, this strategy is applied to synthesize other mono-, di-, and tri-fluoroarylated indole derivatives.

Library of mild and economic protocols for the selective derivatization of sucrose under microwave irradiation

The chemistry of sucrose is very challenging due to its eight hydroxyl groups, three of which are primary, with very similar reactivities, thus control of the chemoselectivity is a central issue. In this work, the selective formation of monounsaturated esters at the 6-position, by applying the Mitsunobu conditions for the selective esterification of sucrose, is reported. Also, the outcome of a number of mono-substitution reactions at positions 6 or 6′, and di-substitution reactions at positions 6 and 6′ have been explored. Mild and energy-efficient procedures, with short reaction times (5 to 10 min) using microwave irradiation have been developed, and the results compared with conventional procedures. In some cases, the use of microwave irradiation appeared to provide not only time saving but also improved selectivity.

Thiol addition to t-butyl methyl squarate. Efficient synthesis of novel sulfur-linked squaryl group-containing glutamate analogs

Novel sulfur-linked squaryl group-containing glutamate analogs were synthesized via addition and mono-substitution reactions of thiols to t-butyl methyl squarate (BMSQ: 7) in two steps. A glutamate analog prepared from Boc- l-Cys showed a potent binding affinity to KA/AMPA receptors.

Gold Catalysis: Selectivity Problems in Hydroarylations with Pyrroles

AbstractGold‐catalyzed reactions of pyrrole derivatives with methyl vinyl ketone preferentially give rise to doubly substituted products, with an excess of methyl vinyl ketone even triple substitutions can be observed. This is independent of the electronic nature of substituents on the pyrrole ring, even substrates with electron‐withdrawing acyl substituents in 1‐, 2‐ or 3‐position show this behavior. The NH group of the pyrrole ring may be unprotected, no competing hydroamination is observed. In an intramolecular competition experiment with a furan ring only the pyrrole ring reacted. The constitutions of the highly‐substituted pyrroles were proven by NMR spectroscopy and one X‐ray structure analysis. Control experiments show that Yb(OTf)3 does not catalyze these reactions, but Ag+ and H+ does. Contrary to pyrroles, under similar reaction conditions indoles show a clean monosubstitution reaction. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Substitution Reactions of Mono- and Trichloro Acetic Acids with Ammonium Dialkyl (Alkylene) Dithiophosphates

A reaction of mono- and trichloro acetic acid with ammonium salts of alkylene (dialkyl) dithiophosphate; [S2NH4; G = ─CH2CH2CHMe─, ─C(Me)2C(Me)2─, ─CH2C(Me)2CH2─, and ─C(Me)2CH2CHMe─; (RO)2PS2-NH4; and R = C2H5, C3H7, i-C3H7;] in a 1:1 molor ratio in refluxing benzene solution yields low melting solids and light-yellow oily liquids of the type [(RO)2PS2R' and S2R′, where R′ = CH2COOH and Cl2CCOOH], which are hygroscopic in nature. These newly synthesized complexes have been characterized by physicochemical and spectroscopic techniques (MW, IR, 1H, and 31PNMR) On the basis of the previously discussed studies, the formation of a P─S─C chemical bond has been established.

Chirality in cyclotriphosphazenes with one stereogenic centre

Mono-substitution reactions of gem symmetrically disubstituted cyclophosphazenes such as (1) and (2) provide a convenient way to investigate the chiral configurational properties of cyclophosphazene compounds with one stereogenic centre. Previous work by X-ray crystallography has shown that the mono-dibenzylamino derivative of (1), compound (3a), is chiral and exists as a racemate. In this work, compound (1) was reacted with piperidine, dimethylamine, pyrrolidine and phenol to give compounds (3b–3e), respectively, and compound (2) was reacted with dimethylamine to give (4). The structures and stereogenic properties of new compounds (3b), (3c) and (4) were determined by X-ray crystallography and, together with compound (3a), the chirality was confirmed by 31P NMR spectroscopy on addition of a chiral solvating agent (CSA), (S)-(+)-2,2,2-trifluoro-1-(9′-anthryl)ethanol. As compound (3d) did not give crystals suitable for X-ray crystallography and compound (3e) is an oil, their stereogenic properties were confirmed by 31P NMR spectroscopy on addition of CSA. The work confirms that cyclophosphazene derivatives containing one centre of chirality exist as racemates and shows that the chiral properties of such molecules may be determined by 31P NMR spectroscopy on addition of a chiral solvating agent in those cases where X-ray crystal structures are not available.

Mono- and disubstitutions of (hepta-2,5-diyne-1,7-diol) bis(dicobalt) derivatives — Selectivity in Nicholas reactions

Bis(hexacarbonyldicobalt) complexes of benzyl ether – methyl ether or benzyl ether – acetate derivatives of hepta-2,5-diyne-1,7-diols undergo selective Lewis-acid-mediated Nicholas reactions with enol silanes, silyl ketene acetals, and allylstannanes, preferentially replacing the methyl ether or acetate function. Hydride nucleophiles are similarly incorporated selectively using a benzyl ether – alcohol derivative. Subsequent Nicholas reaction at the benzyloxy-bearing site may be accomplished with an identical or a different nucleophile, affording skipped 1,4-diyne-Co4(CO)12 complexes. In instances of lower selectivity for monosubstitution reactions with benzyl ethers, reverting to the use of a menthyl ether – methyl ether complex gives much improved selectivity for methyl ether substitution.Key words: cobalt alkyne complexes, Nicholas reaction, Lewis acids, 1,4-diynes.

Synthesis and complexation properties towards amino acids of mono-substituted p-sulphonato-calix-[ n]-arenes

A series of mono-hydroxy functionalised calix-[ n]-arenes, and p-sulphonato-calix-[ n]-arenes where n=4, 6 and 8, have been synthesised, with the pendant functions being ethoxycarbonyl methoxy group, 2-carboxy methoxy group, 2-amido methoxy group or 2-amino ethoxy group. With calix-[4]-arene and calix-[6]-arenes the compounds are obtained in good yield by treatment of the relevant p-H-calix-[ n]-arene with a suitable metal carbonate, as a weak base, in the presence of one equivalent of the corresponding alkyl bromide. However in the case of calix-[8]-arene, the extremely low solubility of p-H-calix-[8]-arene prevented its use and p- tBu-calix-[8]-arene was used in the monosubstitution reactions. The corresponding sulphonate derivatives were prepared in the case of the 2-carboxy methoxy group, 2-amido methoxy group and 2-amino ethoxy group systems, either by sulphonation of the para-H derivatives or by ipso-sulphonation of the tert-butyl derivatives. The complexation properties of the water-soluble p-sulphonato-derivatives with regard to 11 amino acids have been studied by 1H NMR titration experiments. The obtained association constants show a 1:1 stoichiometry. The presence of a pendant group at the lower rim of calix strongly modifies the observed association constant as compared to the parent p-sulphonato-calix-[ n]-arenes. While generally, the cationic amino acids lysine and arginine bind strongly to all the derivatives, the binding of other amino acids is dependant on the nature of the pendant functions, in particular pendant arm-lateral chain function leads to strong binding with aspartic acid, serine and tryptophan.

New carbon[sbnd]carbon bond forming reactions of cyclic sulfate esters and cyclic sulfamidates

Carbon–carbon bonding forming reactions of two cyclic sulfate esters and a cyclic sulfamidate are reported, the former with lithium dianions to give substituted tetrahydrofuran derivatives with displacement of sulfate, and the latter undergoes ring-opening monosubstitution reactions with stabilised organolithiums and an organocuprate species.

Synthesis and characterization of per/polyfluorophenoxy derivatives of octachlorocyclotetraphosphazenes

Octachlorocyclotetraphosphazene was treated with various fluorinated phenols to form partially and completely substituted cyclotetraphosphazenes. The mono-substitution reactions were carried out using a base in benzene while for complete substitution sodium salts of the corresponding phenoxides were used. All compounds were characterized by 1H, 19F, and 31P NMR, IR and mass spectroscopic methods. A crystal structure was obtained for N 4P 4(OC 6F 5) 8, and shows that the phosphazene ring is puckered. The angle of the planes N2P2N1P1N4 to N4P4N3P3N2 is 45.5° and the angle of the planes N1P1N4P4N3 to N3P3N2P2N1 is 43.8°.

ChemInform Abstract: Synthesis and Nucleophilic Substitution Reactions of Mono α‐Fluoro Ethers.

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