High-Load, Soluble Oligomeric Carbodiimide:  Synthesis and Application in Coupling Reactions

Zhang, Mianji; Vedantham, P.; Flynn, Daniel L.; Hanson, Paul R.

doi:10.1021/jo048870c

Cited by 44 publications

(20 citation statements)

References 21 publications

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“…N ‐ n ‐Butylbenzamide (3af): 25 1 H NMR (200 MHz, CDCl 3 ): δ = 7.81–7.68 (m, 2 H), 7.52–7.29 (m, 3 H), 6.45 (s, 1 H), 3.51–3.32 (m, 2 H), 1.68–1.46 (m, 2 H), 1.47–1.27 (m, 2 H), 0.92 (t, J = 7.2 Hz, 3 H) ppm. 13 C NMR (75 MHz, CDCl 3 ): δ = 167.7, 134.9, 131.3, 128.5, 127.0, 39.9, 31.8, 20.2, 13.8 ppm.…”

Section: Methodsmentioning

confidence: 99%

Iron/Caffeine as a Catalytic System for Microwave‐Promoted Benzamide Formation

2014

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The amide bond is an essential unit in many drugs and polymers. The catalyzed oxidation of alcohols and amines is an effective method to form amides with limited undesired waste. Herein, we demonstrate the beneficial effect of microwave activation for this reaction. The benzamides were directly formed from alcohols and amine hydrochloride salts in short reaction times with yields up to 84 % and TOFs (turnover frequencies) up to 33.6 h–1. Among the examined transition metals, only nontoxic and inexpensive FeCl2·4H2O together with caffeine as a stabilizing ligand provided a uniquely efficient catalytic system for the transformation. Natural sources of caffeine were also evaluated under the amidation conditions.

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Section: Methodsmentioning

confidence: 99%

Iron/Caffeine as a Catalytic System for Microwave‐Promoted Benzamide Formation

2014

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“…Carbodiimides, due to their accessibility and versatility, are ranked as one of the most important classes of compounds in organic chemistry . The most widely used carbodiimide reagent, dicyclohexylcarbodiimide (DCC), makes insoluble urea byproducts requiring additional cumbersome purifications . Hence we chose EDCI, a water‐soluble carbodiimide with a water‐soluble urea byproduct, combined with DMAP which has been shown to increase the efficiency of esterification by 10 4 ‐fold .…”

Section: Introductionmentioning

confidence: 99%

Comparison of three methods for the methylation of aliphatic and aromatic compounds

Lee

Feakins

Lü

et al. 2017

Rapid Comm Mass Spectrometry

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RationaleMethylation protocols commonly call for acidic, hot conditions that are known to promote organic 1 H/ 2 H exchange in aromatic and aliphatic C-H bonds. Here we tested two such commonly-used methods and compared a third that avoids these acidic conditions, to quantify isotope effects with each method and to directly determine acidic-exchange rates relevant to experimental conditions. MethodsWe compared acidic and non-acidic methylation approaches catalyzed by hydrochloric acid, acetyl chloride and EDCI (1-ethyl-3-(3-dimethylaminopropyl)carbodiimide) / DMAP (4-dimethylaminopyridine) respectively. These were applied to two analytes: phthalic acid (an aromatic) and octacosanoic acid (an aliphatic). We analyzed yield by gas chromatography flame ionization (GC/FID) and hydrogen and carbon isotopic composition by isotope ratio mass spectrometry (GC/IRMS). We quantified the 1 H/ 2 H exchange rate on dimethyl phthalate under acidic conditions with proton nuclear magnetic resonance ( 1 H-NMR) measurements. ResultsThe δ 2 H and δ 13 C values and yield were equivalent among the three methods for methyl octacosanoate. The two acidic methods resulted in comparable yield and isotopic composition of dimethyl phthalate; however, the non-acidic method resulted in lower δ 2 H and δ 13 C values perhaps due to low yields. Concerns over acid-catalyzed 1 H/ 2 H exchange are unwarranted as the effect was trivial over a 12-hour reaction time.This article is protected by copyright. All rights reserved. ConclusionsWe find product isolation yield and evaporation to be the main concerns in the accurate determination of isotopic composition. 1 H/ 2 H exchange reactions are too slow to cause measurable isotope fractionation over the typical duration and reaction conditions used in methylation. Thus, we are able to recommend continued use of acidic catalysts in such methylation reactions for both aliphatic and aromatic compounds.

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“…14 This high load reagent allows for efficient coupling of a variety of acids with 18 , 19 or 20 , followed by facile removal via a simple precipitation/filtration protocol.…”

Section: Resultsmentioning

confidence: 99%

Triazole-Containing Isothiazolidine 1,1-Dioxide Library Synthesis: One-Pot, Multi-Component Protocols for Small Molecular Probe Discovery

et al. 2011

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The construction of two libraries of triazole-containing isothiazolidine 1,1-dioxides is reported utilizing either a one-pot click/aza-Michael or click/OACC esterification protocol. One core dihydroisothiazole 1,1-dioxide scaffold was prepared rapidly on multi-gram scale via RCM and was subjected to a one-pot multi-component click/aza-Michael protocol with an array of amines and azides for the generation of a 180-member triazole-containing isothiazolidine 1,1-dioxide library. Alternatively, three daughter scaffolds were generated via the aza-Michael of three amino alcohols, followed by a one-pot, multi-component click/esterification protocol utilizing a ROMP-derived coupling reagent, oligomeric alkyl carbodiimide (OACC) to generate a 41-member library of triazole-containing isothiazole 1,1-dioxides.

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High-Load, Soluble Oligomeric Carbodiimide: Synthesis and Application in Coupling Reactions

Cited by 44 publications

References 21 publications

Iron/Caffeine as a Catalytic System for Microwave‐Promoted Benzamide Formation

Iron/Caffeine as a Catalytic System for Microwave‐Promoted Benzamide Formation

Comparison of three methods for the methylation of aliphatic and aromatic compounds

Triazole-Containing Isothiazolidine 1,1-Dioxide Library Synthesis: One-Pot, Multi-Component Protocols for Small Molecular Probe Discovery

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