- Photo-on-Demand Base-Catalyzed Phosgenation Reactions with Chloroform: Synthesis of Arylcarbonate and Halocarbonate Esters
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Carbonate esters are utilized as solvents and reagents for C1 building blocks in organic synthesis. This study reports a novel photo-on-demand in situ synthesis of carbonate esters with CHCl3 solutions containing a mixture of an aromatic or haloalkyl alcohol having relatively high acidity, and an organic base. We found that the acid-base interaction of the alcohol and base in the CHCl3 solution plays a key role in enabling the photochemical reaction. This reaction allows practical syntheses of diphenyl carbonate derivatives, haloalkyl carbonates, and polycarbonates, which are important chemicals and materials in industry.
- Dai, Namin,Eda, Kazuo,Harada, Hidefumi,Hashimoto, Yuka,Hosokawa, Sasuga,Kakiuchi, Toshifumi,Liang, Fengying,Okazoe, Takashi,Suzuki, Yuto,Tana, Gegen,Tsuda, Akihiko
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p. 9811 - 9819
(2021/07/20)
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- CARBONATE DERIVATIVE PRODUCTION METHOD
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The objective of the present invention is to provide a method for producing a carbonate derivative in a safe and efficient manner. The method for producing a carbonate derivative according to the present invention is characterized in comprising irradiating light on a composition containing a C1-4 halogenated hydrocarbon having one or more kinds of halogen atoms selected from the group consisting of a chlorine atom, a bromine atom and an iodine atom, a nucleophilic functional group-containing compound and the specific base in the presence of oxygen.
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Paragraph 0135-0136; 0141-0142
(2020/04/09)
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- Alkyl and aryl 4,5-dichloro-6-oxopyridazin-1(6 H)-carboxylates: A practical alternative to chloroformates for the synthesis of symmetric and asymmetric carbonates
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Symmetric and asymmetric carbonates were synthesized by using alkyl or aryl 4,5-dichloro-6-oxopyridazin-1(6H)-carboxylates. Five aryl 4,5-dichloro-6-oxopyridazin-1(6H)-carboxylates were converted into the corresponding diaryl carbonates in good to excellent yields by treatment with potassium carbonate in refluxing THF. When the 4,5-dichloro-6-oxopyridazin-1(6H)-carboxylates were treated with aliphatic or aromatic alcohols in the presence of potassium tert-butoxide in toluene at room temperature, they gave the corresponding symmetric or asymmetric carbonates in moderate to excellent yields. Alkyl and aryl 4,5-dichloro-6-oxopyridazin-1(6H)-carboxylates are therefore efficient, stable, and ecofriendly alternatives to chloroformates.
- Moon, Hyun Kyung,Sung, Gi Hyeon,Yoon, Yong-Jin,Yoon, Hyo Jae
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supporting information
p. 1577 - 1581
(2016/06/14)
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- Synthesis of organic carbonates with alkyl/aryl 4,5-dichloro-6-oxopyridazine-1(6H)-carboxylates and ROH/AlCl3under ambient condition
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We demonstrated the synthesis of organic carbonates using alkyl/aryl 4,5-dichloro-6-oxopyridazine-1(6H)-carboxylates and alcohol in the presence of aluminum chloride. Alkyl/aryl 4,5-dichloro-6-oxopyridazine-1(6H)-carboxylates were reacted with alcohol in the presence of AlCl3 in toluene at room temperature to afford the corresponding unsymmetric and symmetric organic carbonates in good to excellent yields. These are efficient and convenient processes. Alkyl/aryl 4,5-dichloro-6-oxopyridazine-1(6H)-carboxylates are solid, stable and non-toxic CO2/CO2R(Ar) source. It is noteworthy that the reaction is carry out under an ambient and acidic conditions, the easy-to prepare and readily available starting materials and the quantitative isolation of reusable 4,5-dichloropyridazin-3(2H)-one.
- Sung, Gi Hyeon,Bo, Ram Kim,Ryu, Ki Eun,Kim, Jeum-Jong,Yoon, Yong-Jin
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p. 2758 - 2764
(2015/04/22)
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- Double- and triple-consecutive O-insertion into tert-butyl and triarylmethyl structures
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(Matrix Presented) The concecutive Criegee rearrangement reactions were studied for tert-butyl trifluoroacetate, triarylcarbinols, and benzophenone ketales with trifluoroperacetic acid (TFPAA) in trifluoroacetic acid (TFA). The formation of methyl acetate and methyl trifluoroacetate indicates that the consecutive double-O-insertion process has taken place for tert-butyl trifluoroacetate. The intermediate dimethoxymethylcarbonium ion was detected below 5°C. A consecutive triple-O-insertion process has been observed for triarylmethanols and benzophenone ketals. A new high yield method of corresponding diaryl carbonates synthesis was developed.
- Krasutsky, Pavel A.,Kolomitsyn, Igor V.,Krasutsky, Sergiy G.,Kiprof, Paul
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p. 2539 - 2542
(2007/10/03)
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- PEPTIDIC THROMBIN INHIBITOR COMPOUND
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The present invention relates to a novel thrombin inhibitor compound which has a good inhibitory effect against thrombosis and can be orally administered, a process for preparing the same, and to a composition for the therapeutic and/or prophylactic treatment of various diseases associated with thrombin inhibition mechanism, which comprises the same as an active ingredient.
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- BENZAMIDINE DERIVATIVE
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Compounds of general formula (1) and pharmacologically acceptable salts thereof: ???[wherein ??????R1 represents a hydrogen atom, a halogen atom, an alkyl group or a hydroxyl group; ??????R2 represents a hydrogen atom or a halogen atom; ??????R3 represents a hydrogen atom, an alkyl group which may be substituted, an aralkyl group, an alkylcarbonyl group which may be substituted, an alkylsulfonyl group which may be substituted or the like; ??????each of R4 and R5 represents a hydrogen atom, a halogen atom, an alkyl group which may be substituted, a carbamoyl group or the like; ??????R6 represents a heterocycle or the like; ??????each of R7 and R8 represents a hydrogen atom, an alkyl group or the like; ??????n represents 0, 1 or 2] ???exhibit excellent activated blood coagulation factor X inhibitory activity and are useful for the prevention or treatment of blood coagulation-related diseases.
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- Novel prodrugs for antimicrobial amidines
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A methods of treating an infection comprises administering a therapeutically effective amount of a compound described by the Formula (I): wherein: X may be O, S, or NR′ wherein R′ is H or loweralkyl; R1 and R2 may be independently selected from the group consisting of H, loweralkyl, oxyalkyl, alkoxyalkyl, cycloalkyl, aryl, hydroxyalkyl, aminoalkyl, and alkylaminoalkyl; R3 and R4 are each independently selected from the group consisting of H, loweralkyl, halogen, oxyalkyl, oxyaryl, and oxyarylalkyl; R5 is represented by a formula selected from the group consisting of: ?wherein: X1, X2, and X3 are independently selected from O and S; and R6 and R7 are independently selected from the group consisting of loweralkyl, aryl, alkylaryl, oxyaryl, an ester-containing substituent, and oxyalkyl; or a pharmaceutically acceptable salt thereof.
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- Kinetic study of the phenolysis of bis(4-nitrophenyl) carbonate, bis(4-nitrophenyl) thionocarbonate, and methyl 4-nitrophenyl thionocarbonate
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The reactions of a homogeneous series of phenols with bis(4-nitrophenyl) carbonate (BNPC), bis-(4-nitrophenyl) thionocarbonate (BNPTOC), and methyl 4-nitrophenyl thionocarbonate (MNPTOC) are subjected to a kinetic investigation in water, at 25.0 °C and ionic strength of 0.2 M (KCl). Under excess of phenol over the substrate, all the reactions obey pseudo-first-order kinetics and are first order in phenoxide anion. The reactions of BNPC show a linear Broensted-type plot with slope β=0.66, consistent with a concerted mechanism (one step). In contrast, those of BNPTOC and MNPTOC show biphasic Broensted-type plots with slopes β=0.30 and 0.44, respectively, at high pKa, and β=1.25 and 1.60, respectively, at low pKa, consistent with stepwise mechanisms. For the reactions of both thionocarbonates, the pKa value at the center of the BrSnsted plot (pKa0) is 7.1, which corresponds to the pKa of 4-nitrophenol. This confirms that the phenolyses of the thionocarbonates are stepwise processes, with the formation of an anionic tetrahedral intermediate. By the comparison of the kinetics and mechanisms of the title reactions with similar reactions, the following conclusions can be drawn: (i) Substitution of S- by O- in an anionic tetrahedral intermediate (T-) destabilizes it. (ii) The change of MeO by 4-nitrophenoxy in T- results in an increase of both the rate constant and equilibrium constant, for the formation ofT-, and also in an enlargement of the rate coefficient for the expulsion of 4-nitrophenoxide from T-. (iii) Substitution of an amino group in a tetrahedral intermediate by ArO destabilizes it. (iv) Secondary alicyclic amines and other amines show greater reactivity toward MNPTOC than isobasic phenoxide anions.
- Castro,Angel,Arellano,Santos
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p. 6571 - 6575
(2007/10/03)
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- Diaryloxycarbenes from oxadiazolines
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Symmetric and unsymmetric 2,2-diaryloxy-5,5-dimethyl-Δ3-1,3,4-oxadiazolines were synthesized by oxidative cyclization of aryloxycarbonyl hydrazones of acetone with lead tetraacetate and subsequent treatment of the product mixture with a phenol in acidic solution. Thermolysis of the oxadiazolines in benzene solution at 110°C afforded carbonyl ylide intermediates that cyclize, in part, to the corresponding 2,2-diaryloxyoxirane intermediates. The oxiranes, which were not observed, are required to account for the 1,1-diaryloxy-2-methylpropenes (ketene acetals) that were isolated. Most of the carbonyl ylides fragment to acetone and diaryloxycarbenes. The latter form dimers (tetraaryloxyethenes) or they can be trapped with phenols to form orthoformates. Diphenoxycarbene was also trapped with dimethyl acetylenedicarboxylate (DMAD). The method appears to be the first for generating the parent diphenoxycarbene under relatively mild conditions in solution, and the only one to date for generating unsymmetrically substituted diaryloxycarbenes. Minor competing fragmentations of the oxadiazolines to 2-diazopropane and the appropriate diaryl carbonates, were also observed.
- Lu,Reid,Warkentin
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p. 319 - 327
(2007/10/03)
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- Prodrugs for amidines: Synthesis and anti-Pneumocystis carinii activity of carbamates of 2,5-bis(4-amidinophenyl)furan
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Syntheses of several carbamate analogues of 2,5-bis(4- amidinophenyl)furan (1) under mild conditions and their evaluation as prodrugs against Pneumocystis carinii pneumonia (PCP) in an immunosuppressed rat model are described. Thus, nine new bis-carbamates: methoxycarbonyl (2), 2,2,2-trichloroethoxycarbonyl (3), ethylthiocarbonyl (4), benzyloxycarbonyl (5), (4-methyl-2-oxo-1,3-dioxol-4-en-5-yl)methoxycarbonyl (6), phenoxycarbonyl (7), 4-fluorophenoxycarbonyl (8), 4-methoxyphenoxycarbonyl (9), and (1-acetoxy)ethoxycarbonyl (10) and a biscarbonate ethoxycarbonyloxy (1) of the bis-amidine 1 have been synthesized and evaluated. The in vivo results show that the 4-fluorophenyl carbamate 8 and the 4-methoxyphenyl carbamate 9 in this series had the best anti-PCP activity by both intravenous and oral administration at a dosage level of 22 mol and 33 μmol/kg/day, respectively. Compounds 3-7 were also more active than the parent drug (1) on oral administration. The acute toxicity usually exhibited by the parent amidine 1 at a dosage level of 22 μmol/kg/day on intravenous administration has been significantly reduced by the prodrug modifications, with the exception of compound 10 which exhibited some toxicity. This report also describes the synthesis of several aryl-alkyl and aryl-aryl carbonates (12- 14, 16-23) as efficient reagents for the preparation of carbamate derivatives from bis-arylamidines.
- Rahmathullah, Syed M.,Hall, James Edwin,Bender, Brendan C.,McCurdy, Donald R.,Tidwell, Richard R.,Boykin, David W.
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p. 3994 - 4000
(2007/10/03)
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- Hydrolysis of aryl orthocarbonates by general acid catalyzed and spontaneous processes. Characterization of the water reaction of (ArO)3COAr′ and (ArO)3CN3
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Twenty-four aryl orthocarbonates of formula (Aro)4C, (ArO)2C(OAr′)2, or (ArO)3COAr′ have been made by coupling of the copper phenoxides with carbon disulfide, and their hydrolyses have been examined in 60% water-40% acetonitrile (I = 1.00 M, KCl) at 70.0 °C. Their hydrolysis by general acid catalyzed and, in the case of (ArO)3COAr′ when Ar′ = p-nitrophenyl and p-cyanophenyl, spontaneous processes yields aryl carbonates. The initial, rate-determining event for both processes is the cleavage of the bond between the central carbon and the least basic phenoxy group: with mixed orthocarbonates of phenols differing in pK by 6H4O)3C-O-P-C6H 4NO2 and (X-C6H4O)3C-O-p-C6H4CN where the σ value of X varies from -0.23 to 0.22 are 4-10 times slower than reactions of p-nitrophenyl tetrahydropyrans reported in the literature and give rise to nonlinear Hammett plots. However, plots against the pKa of X-C6H4OH are linear, and the derived β(reaction center) values indicate substantial buildup of positive charge on the central carbon atom. A similar plot is obtained for the spontaneous reactions of five azides (XC6H4O)3CN3 for which common ion inhibition experiments have been performed. The derived selectivities (M-1) of the tris(aryloxy)carbenium ion intermediates between azide ion and water vary from 8.5 × 103 to 6.6 × 103 as the σ value of X changes from -0.28 to 0.06. The lifetime of the tris(aryloxy)carbenium ion intermediates in water is therefore likely to be >10-6 s. The slow formation and slow hydrolysis of tris(aryloxy)carbenium ions suggests that (in the formation direction) development of conjugative stabilization lags behind carbon-oxygen bond cleavage and (in the hydrolysis direction) precedes carbon-oxygen bond formation. The stereochemistry of tetraaryl orthocarbonates immediately suggests reasons why this should be so.
- Kandanarachchi, Pramod,Sinnott, Michael L.
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p. 5592 - 5600
(2007/10/02)
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- Hydrolysis of orthocarbonates. Evidence for charge imbalance in the transition state for the general acid catalyzed process
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Catalytic constants have been measured for the hydrolysis of a range of aryl orthocarbonates, in which both the leaving group and trioxocarbenium ion moiety have been systematically varied, by neutral carboxylic acids (trichloroacetic, difluoroacetic, dichloroacetic, malonic, chloroacetic, and acetic) at 70.0°C in 60% water-40% acetonitrile, I = 1.0 M (KCI). Curvature cannot be detected in Br?nsted plots involving carboxylic acids only, but inclusion of the point for H3O+ suggests downward curvature (i.e. px ≥ 0). β1g Plots are curved downward (i.e. py′ = -?β1g/?pK1g > 0). Substitutent effects in the tris(aryloxy)carbenium ion fragment were quantitated by use of the experimental aqueous pKa alues of the phenol (pKrc), rather than Hammett σ values, since this gave better correlations for the spontaneous reactions (Kandanarachchi, P.; Sinnott, M. L. J. Am. Chem. Soc., preceding paper in this issue). Cross coefficients are large and not constant: pxy′ (measured as ?α/?pK1g rather than -?β1g/?pKHA) varies from 0.26 for (PhO)3C+ to 0.16 for (PMeOC6H4O)3C+. Likewise,pxy (measured as -?α/?pKrc rather than -?βrc/?pKHA) experiences large changes with the leaving group pK. Data to estimate pyy′ (?βrc/?pK1g) are more limited, but it too changes with the pKa of the catalyzing acid. These data indicate that a two-dimensional More O'Ferrall-Jencks diagram, with one axis representing both C-O cleavage and the ability of substituents in the tris(aryloxy)carbenium ion moiety to sense positive charge development, is inadequate to represent this reaction: separate axes are required for carbon-oxygen bond cleavage and development of carbon-oxygen double-bond character.
- Kandanarachchi, Pramod,Sinnott, Michael L.
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p. 5601 - 5606
(2007/10/02)
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- Aromatic carbonates
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An aromatic carbonate process comprising contacting a phenol, carbon monoxide, a base, a Group VIIIB element selected from ruthenium, rhodium, palladium, osmium, iridium or platinum having an oxidation state of plus one. The resulting aromatic mono- and polycarbonates are useful in the preparation of polycarbonates or as polycarbonates, per se, respectively, which can be molded or formed into films, sheets, fibers, laminates or reinforced plastics by conventional techniques.
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