Reaction of t-Ethinyl Alcohols with Aryl Isocyanates

Shapiro, Seymour L.; Bandurco, Victor T.; Freedman, Louis

doi:10.1021/jo01068a021

Cited by 21 publications

(8 citation statements)

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“…The reactivity of the alcohols was highest for MeOH, and decreased with increasing the alkyl chain length (entries [1][2][3][4][5]. This result may be ascribed to stronger inductive effect on the carbonyl of urea with higher polarity of the longer chain alcohol.…”

Section: The Influence Of the Alcohol Typementioning

confidence: 94%

“…The maximum yield of 2 was 89.1%, which was obtained at a Zn/AlPO 4 molar ratio of 0.04:1. The selectivity for dibutyl carbonate (3) and butyl carbamate (4) first decreased and then increased slightly, with increasing Zn/AlPO 4 from 0:1 to 0.08:1. The selectivity for 2 exhibited an inverse trend with Zn/AlPO 4 molar ratio, compared with that for 3 and 4, and achieved a maximum value at Zn/AlPO 4 = 0.04:1.…”

Section: Catalytic Activity Of Zn/alpo 4 Catalysts At Different Molarmentioning

confidence: 96%

“…Currently, carbamates are commercially prepared by the reaction between alcohols and toxic isocyanates [3]. However, a number of drawbacks may occur in the route, including difficult handling of the toxic phosgene and the seriously corrosive side product HCl [2].…”

Section: Introductionmentioning

confidence: 99%

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One-Pot Synthesis of Dialkyl Hexane-1,6-Dicarbamate from 1,6-Hexanediamine, Urea, and Alcohol over Zinc-Incorporated Berlinite (ZnAlPO4) Catalyst

et al. 2016

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Dialkyl hexane-1,6-dicarbamate was synthesized, for the first time, by a one-pot reaction of 1,6-hexanediamine (HDA), urea, and alcohols, including methanol, ethanol, propanol, and butanol, in a self-designed batch reactor, using zinc-incorporated berlinite (ZnAlPO 4 ) as a catalyst. The yield of dibutyl hexane-1,6-dicarbamate (2) was systematically investigated as a function of Zn/Al molar ratio, reaction temperature, reaction time, catalyst usage and urea/HDA/butanol molar ratio. Based on these studies, the optimized reaction conditions were as follows: molar ratio urea/HDA/ butanol = 2.6:1:8.6, catalyst usage = 3.0 g, reaction temperature = 493 K, reaction time = 6 h and reaction pressure = 1.2 MPa; a yield of 2 of 89.7% was achieved over the ZnAlPO 4 (molar ratio Zn/Al = 0.04) catalyst. The catalysts were characterized by X-ray photoelectric spectroscopy (XPS) and scanning electron microscope (SEM). Additionally, based on these experimental results, it was also proposed that the catalysis recycle of the one-pot synthesis of 2 from urea, HDA, and butanol over the ZnAlPO 4 catalyst.

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Section: The Influence Of the Alcohol Typementioning

confidence: 94%

Section: Catalytic Activity Of Zn/alpo 4 Catalysts At Different Molarmentioning

confidence: 96%

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One-Pot Synthesis of Dialkyl Hexane-1,6-Dicarbamate from 1,6-Hexanediamine, Urea, and Alcohol over Zinc-Incorporated Berlinite (ZnAlPO4) Catalyst

et al. 2016

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confidence: 99%

“…Once deprotected, the 2¢-OH could attack the ethynyl group and create a vinyl carbanion intermediate E. Both the electron-withdrawing effect of the fluorine at C-3a stabilizing the intermediate E and the energetics of the dihydrofuran cyclization could promote the reaction. 18 The conformationally restricted 2¢-O,3¢-C-vinylenelinked bicyclic nucleoside analogue 10, which fuses an unsaturated vinyl group and a fluorine atom in the carbohydrate moiety, is important to our antiviral and anticancer nucleoside research program because of its structural novelty within the field as suggested by Wengel and coworkers. 21b Other naturally occuring bicyclic nucleosides show important biological activities, 19 and a plethora of conformationally restricted bicyclic nucleosides have been synthesized for potential antiviral activities.…”

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confidence: 99%

Design and Synthesis of 3′-Deoxy-3′-Fluoro-2′-O,3′-C-Vinylene-Linked Bicyclic Purine Nucleoside

Zhao¹,

Chang²,

Wang³

et al. 2008

Synlett

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Starting from D-xylose via a 3-deoxy-3a-C-ethynyl-3-fluoro sugar as a key intermediate, a novel fluorinated bicyclic purine nucleoside has been synthesized. A neighboring-group participation pathway and a mechanism involving an intramolecular cycloaddition induced by fluorine are proposed for the formation of the key intermediate and the bicyclic nucleoside, respectively.Nucleoside analogues, some of which remain in the forefront of anti-HIV and anti-HBV chemotherapeutic regimens, 1,2 play an important role in the control of viral diseases and cancer. However, side effects and drug-resistant mutants continue to be problematic with these agents. As a result, the development of structurally new, more potent, and less toxic nucleoside derivatives is in demand. 2 Modification of the carbohydrate moiety of nucleosides with the electron-withdrawing fluorine atom has been extensively applied in the design of such analogues, as this can greatly affect the electronic structure of a nucleoside often leading to dramatically improved activities 3 without significantly altering its shape and size. 4 In addition, the ethynyl group, which has characteristic electronic and structural features due to its sp-hybridization, is present in many biologically active compounds, 5 and its introduction into the natural nucleoside structure sometimes produces potent antimetabolites. 6-9,2b The 1-(3-C-ethynyl-b-D-ribopentofuranosyl) cytosine (Ecyd), for example, exhibits good activity against various human solid tumors and is undergoing human clinical trials. 10 These encouraging results have prompted us to synthesize nucleosides modified with both fluoro and ethynyl groups, such as 2¢-fluoro-2¢-deoxy-3¢b-C-ethynyl nucleosides or 3¢-fluoro-3¢-deoxy-3¢a-C-ethynyl nucleosides, in order to discover novel drugs. The related compounds, 3¢-fluoro-2¢,3¢-dideoxy-2¢,3¢-didehydro-4¢-ethynyl nucleosides 2a and 2¢-fluoro-2¢-deoxy-3¢a-C-ethynyl nucleosides 11 have been previously prepared among which the 3¢-fluoro-2¢,3¢-dideoxy-2¢,3¢-didehydro-4¢-ethynyl-D-adenine showed moderate anti-HIV activity without cytotoxicity. In the course of preparing a 2¢-fluoro-2¢-deoxy-3¢b-C-ethynyl derivative, an unusual fluorination of hydroxyl intermediate 4 was observed to furnish the 3-fluoro-3-deoxy-3a-Cethynyl sugar 6 and not the expected fluorination product 5. In a subsequent transformation, we have observed a fluorine-induced intramolecular cyclization to produce the novel fluorinated bicyclic purine nucleoside {(3aS,4R,6S,6aS)-3a-fluoro-6-(6-methoxy-7H-purin-7-yl)-3a,4,6,6a-tetrahydrofuro[3,2-c]-furan-4-yl} methanol (10).The starting material for our synthetic route (Scheme 1) was D-xylose (1), which was converted to the 3b-C-ethynyl sugar 2 in five steps by a known procedure. 12Benzoylation of 2 in a mixture of BzCl, DMAP, and Et 3 N followed by methanolysis with concentrated HCl in aqueous MeOH at 55 °C for 4 hours gave the intermediate 4 22,23 as the sole isomer in 75% yield. 1 H NMR spectrum of 4 showed that the proton signal for H-1 (d = 5.56 ppm) appeared...

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Steroidal 4‐methylene‐2‐oxoazolidinones

Moersch¹,

Creger²

1965

Journal of Heterocyclic Chem

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Reaction of t-Ethinyl Alcohols with Aryl Isocyanates

Cited by 21 publications

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One-Pot Synthesis of Dialkyl Hexane-1,6-Dicarbamate from 1,6-Hexanediamine, Urea, and Alcohol over Zinc-Incorporated Berlinite (ZnAlPO4) Catalyst

One-Pot Synthesis of Dialkyl Hexane-1,6-Dicarbamate from 1,6-Hexanediamine, Urea, and Alcohol over Zinc-Incorporated Berlinite (ZnAlPO4) Catalyst

Design and Synthesis of 3′-Deoxy-3′-Fluoro-2′-O,3′-C-Vinylene-Linked Bicyclic Purine Nucleoside

Steroidal 4‐methylene‐2‐oxoazolidinones

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Reaction of t-Ethinyl Alcohols with Aryl Isocyanates

Cited by 21 publications

References 0 publications

One-Pot Synthesis of Dialkyl Hexane-1,6-Dicarbamate from 1,6-Hexanediamine, Urea, and Alcohol over Zinc-Incorporated Berlinite (ZnAlPO4) Catalyst

One-Pot Synthesis of Dialkyl Hexane-1,6-Dicarbamate from 1,6-Hexanediamine, Urea, and Alcohol over Zinc-Incorporated Berlinite (ZnAlPO4) Catalyst

Design and Synthesis of 3′-Deoxy-3′-Fluoro-2′-O,3′-C-Vinylene-Linked ­Bicyclic Purine Nucleoside

Steroidal 4‐methylene‐2‐oxoazolidinones

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Product

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Design and Synthesis of 3′-Deoxy-3′-Fluoro-2′-O,3′-C-Vinylene-Linked Bicyclic Purine Nucleoside