Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Reaction of isonitriles with carboxylic acids in a cavitand: observation of elusive isoimide intermediates.

ABSTRACT: A deep cavitand with an inwardly directed carboxylic acid function reacts with small aliphatic isonitriles to form N-acyl formamides inside the cavity. The unique isolation and stabilization of covalently bound guests within the structured environment of the cavitand allows for observation of the labile O-acyl isoimide intermediate using conventional spectroscopic methods.

SUBMITTER: Restorp P

PROVIDER: S-EPMC2642476 | biostudies-literature | 2008 Sep

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Reaction of isonitriles with carboxylic acids in a cavitand: observation of elusive isoimide intermediates.

Restorp Per P Rebek Julius J

Journal of the American Chemical Society 20080813 36

A deep cavitand with an inwardly directed carboxylic acid function reacts with small aliphatic isonitriles to form N-acyl formamides inside the cavity. The unique isolation and stabilization of covalently bound guests within the structured environment of the cavitand allows for observation of the labile O-acyl isoimide intermediate using conventional spectroscopic methods. ...[more]

PMID: 18698780

Similar Datasets

Modeling the Reaction of Carboxylic Acids and Isonitriles in a Self-Assembled Capsule.

Project description:Quantum chemical calculations were used to study the reaction of carboxylic acids with isonitriles inside a resorcinarene-based self-assembled capsule. Experimentally, it has been shown that the reactions between p-tolylacetic acid and n-butyl isonitrile or isopropyl isonitrile behave differently in the presence of the capsule compared both with each other and also with their solution counterparts. Herein, the reasons for these divergent behaviors are addressed by comparing the detailed energy profiles for the reactions of the two isonitriles inside and outside the capsule. An energy decomposition analysis was conducted to quantify the different factors affecting the reactivity. The calculations reproduce the experimental findings very well. Thus, encapsulation leads to lowering of the energy barrier for the first step of the reaction, the concerted α-addition and proton transfer, which in solution is rate-determining, and this explains the rate acceleration observed in the presence of the capsule. The barrier for the final step of the reaction, the 1,3 O→N acyl transfer, is calculated to be higher with the isopropyl substituent inside the capsule compared with n-butyl. With the isopropyl substituent, the transition state and the product of this step are significantly shorter than the preceding intermediate, and this results in energetically unfavorable empty spaces inside the capsule, which cause a higher barrier. With the n-butyl substituent, on the other hand, the carbon chain can untwine and hence uphold an appropriate guest length.

| S-EPMC7522688 | biostudies-literature

On the two-component microwave-mediated reaction of isonitriles with carboxylic acids: regarding alleged formimidate carboxylate mixed anhydrides.

Project description:Microwave induced two-component coupling (2CC) reaction of carboxylic acids with isonitriles gives rise to various N-formylamides. The formimidate carboxylate mixed anhydride (FCMA) is proposed as the reactive intermediate, which undergoes 1,3-O-->N acyl transfer to give the observed product. The formation and survival of the labile FCMA system has been evaluated.

| S-EPMC2580818 | biostudies-literature

New chemistry with old functional groups: on the reaction of isonitriles with carboxylic acids--a route to various amide types.

Project description:Thermolysis of isonitriles with carboxylic acids provides, in one step, N-formyl imides (see, for example, 8 + 19 --> 21). The resultant N-formyl group can be converted to N-H, NCH2OH, or NCH3. This chemistry allows for a new route for synthesizing beta-N (asparagine)-linked glycosyl amino acids.

| S-EPMC2580817 | biostudies-literature

Addressing mechanistic issues in the coupling of isonitriles and carboxylic acids: potential routes to peptidic constructs.

Project description:Mechanistic issues surrounding the two component coupling (2CC) reaction of carboxylic acids with isonitriles have been investigated. Experimental details suggest the formimidate carboxylate mixed anhydride intermediate exists in both interdictable and noninterdictable form. Furthermore, the 2CC reaction has been applied to the synthesis of a tripeptide featuring two formyl functional groups.

| S-EPMC2580816 | biostudies-literature

Doebner-type pyrazolopyridine carboxylic acids in an Ugi four-component reaction.

Project description:Substituted 1H-pyrazolo[3,4-b]pyridine-4- and 1H-pyrazolo[3,4-b]pyridine-6-carboxamides have been synthetized through a Doebner-Ugi multicomponent reaction sequence in a convergent and versatile manner using diversity generation strategies: combination of two multicomponent reactions and conditions-based divergence strategy. The target products contain as pharmacophores pyrazolopyridine and peptidomimetic moieties with four points of diversity introduced from readily available starting materials including scaffold diversity. A small focused compound library of 23 Ugi products was created and screened for antibacterial activity.

| S-EPMC6604699 | biostudies-literature

Direct Observation of Intermediates Involved in the Interruption of the Bischler-Napieralski Reaction.

Project description:The first mechanistic investigation of electrophilic amide activation of ?,?-disubstituted tertiary lactams and the direct observation of key intermediates by in situ FTIR, (1)H, (13)C, and (19)F NMR in our interrupted Bischler-Napieralski-based synthetic strategy to the aspidosperma alkaloids, including a complex tetracyclic diiminium ion, is discussed. The reactivity of a wide range of pyridines with trifluoromethanesulfonic anhydride was systematically examined, and characteristic IR absorption bands for the corresponding N-trifluoromethanesulfonylated pyridinium trifluoromethanesulfonates were assigned. The reversible formation of diiminium ether intermediates was studied, providing insight into divergent mechanistic pathways as a function of the steric environment of the amide substrate and stoichiometry of reagents. Importantly, when considering base additives during electrophilic amide activation, more hindered ?-quaternary tertiary lactams require the use of non-nucleophilic pyridine additives in order to avoid deactivation via a competing desulfonylation reaction. The isolation and full characterization of a tetracyclic iminium trifluoromethanesulfonate provided additional correlation between in situ characterization of sensitive intermediates and isolable compounds involved in this synthetic transformation.

| S-EPMC4597596 | biostudies-literature

Protein vivisection reveals elusive intermediates in folding.

Project description:Although most folding intermediates escape detection, their characterization is crucial to the elucidation of folding mechanisms. Here, we outline a powerful strategy to populate partially unfolded intermediates: A buried aliphatic residue is substituted with a charged residue (e.g., Leu-->Glu(-)) to destabilize and unfold a specific region of the protein. We applied this strategy to ubiquitin, reversibly trapping a folding intermediate in which the beta5-strand is unfolded. The intermediate refolds to a native-like structure upon charge neutralization under mildly acidic conditions. Characterization of the trapped intermediate using NMR and hydrogen exchange methods identifies a second folding intermediate and reveals the order and free energies of the two major folding events on the native side of the rate-limiting step. This general strategy may be combined with other methods and have broad applications in the study of protein folding and other reactions that require trapping of high-energy states.

| S-EPMC2838964 | biostudies-literature

Isoquinolone-4-Carboxylic Acids by Ammonia-Ugi-4CR and Copper-Catalyzed Domino Reaction.

Project description:Highly substituted isoquinolone-4-carboxylic acid is an important bioactive scaffold; however, it is challenging to access it in a general and short way. A Cu-catalyzed cascade reaction was successfully designed involving the Ugi postcyclization strategy by using ammonia and 2-halobenzoic acids as crucial building blocks. Privileged polysubstituted isoquinolin-1(2H)-ones were constructed in a combinatorial format with generally moderate to good yields. The protocol, with a ligand-free catalytic system, shows a broad substrate scope and good functional group tolerance toward excellent molecular diversity. Free 4-carboxy-isoquinolone is now for the first time generally accessible by a convergent multicomponent reaction protocol.

| S-EPMC8291606 | biostudies-literature

Direct observation of reaction intermediates for a well defined heterogeneous alkene metathesis catalyst.

Project description:Grafting of [W([triple bond]NAr)(=CHtBu)(2,5-Me(2)NC(4)H(2))(2)] on a silica partially dehydroxylated at 700 degrees C (SiO(2- (700))) generates the corresponding monosiloxy complex [([triple bond]SiO)W([triple bond]NAr)(=CHtBu)(2,5-Me(2)NC(4)H(2))] as the major species (approximately 90%) along with [([triple bond]SiO)W([triple bond]NAr)(CH(2)tBu)(2,5-Me(2)NC(4)H(2))(2)], according to mass balance analysis, IR, and NMR studies. This heterogeneous catalyst displays good activity and stability in the metathesis of propene. Very importantly, solid state NMR spectroscopy allows observation of the propagating alkylidene as well as stable metallacyclobutane intermediates. These species have the same reactivity as the initial surface complex [([triple bond]SiO)W([triple bond]NAr)(=CHtBu)(2,5-Me(2)NC(4)H(2))], which shows that they are the key intermediates of alkene metathesis.

| S-EPMC2527876 | biostudies-other

Flavinium Catalysed Photooxidation: Detection and Characterization of Elusive Peroxyflavinium Intermediates.

Project description:Flavin-based catalysts are photoactive in the visible range which makes them useful in biology and chemistry. Herein, we present electrospray-ionization mass-spectrometry detection of short-lived intermediates in photooxidation of toluene catalysed by flavinium ions (Fl+ ). Previous studies have shown that photoexcited flavins react with aromates by proton-coupled electron transfer (PCET) on the microsecond time scale. For Fl+ , PCET leads to FlH.+ with the H-atom bound to the N5 position. We show that the reaction continues by coupling between FlH.+ and hydroperoxy or benzylperoxy radicals at the C4a position of FlH.+ . These results demonstrate that the N5-blocking effect reported for alkylated flavins is also active after PCET in these photocatalytic reactions. Structures of all intermediates were fully characterised by isotopic labelling and by photodissociation spectroscopy. These tools provide a new way to study reaction intermediates in the sub-second time range.

| S-EPMC6852162 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data