Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Boc-protected 1-(3-oxocycloalkyl)ureas via a one-step Curtius rearrangement: mechanism and scope.

ABSTRACT: 1-(3-Oxocyclobutyl) carboxylic acid (4a) was converted into N-Boc-protected 1-(3-oxocyclobutyl) urea (5a), a key intermediates for the preparation of agonists of metabotropic glutamate receptor 5, in one-step when treated with diphenyl phosphoryl azide and triethylamine in tert-butanol. The mechanism of the reaction involves a nucleophilic addition of the in situ generated tert-butyl carbamate to the isocyanate intermediate. This reaction is applicable to other 1-(3-oxocycloalkyl) carboxylic acids but not to linear ?-keto carboxylic acids.

SUBMITTER: Sun X

PROVIDER: S-EPMC3928826 | biostudies-literature | 2014 Jan

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Boc-protected 1-(3-oxocycloalkyl)ureas via a one-step Curtius rearrangement: mechanism and scope.

Sun Xianyu X Rai Rachita R Deschamps Jeffrey R JR Mackerell Alexander D AD Faden Alan I AI Xue Fengtian F

Tetrahedron letters 20140101 4

1-(3-Oxocyclobutyl) carboxylic acid (4a) was converted into N-Boc-protected 1-(3-oxocyclobutyl) urea (5a), a key intermediates for the preparation of agonists of metabotropic glutamate receptor 5, in one-step when treated with diphenyl phosphoryl azide and triethylamine in tert-butanol. The mechanism of the reaction involves a nucleophilic addition of the in situ generated tert-butyl carbamate to the isocyanate intermediate. This reaction is applicable t ...[more]

PMID: 24563555

Similar Datasets

Photoinduced, Copper-Catalyzed Decarboxylative C-N Coupling to Generate Protected Amines: An Alternative to the Curtius Rearrangement.

Project description:The Curtius rearrangement is a classic, powerful method for converting carboxylic acids into protected amines, but its widespread use is impeded by safety issues (the need to handle azides). We have developed an alternative to the Curtius rearrangement that employs a copper catalyst in combination with blue-LED irradiation to achieve the decarboxylative coupling of aliphatic carboxylic acid derivatives (specifically, readily available N-hydroxyphthalimide esters) to afford protected amines under mild conditions. This C-N bond-forming process is compatible with a wide array of functional groups, including an alcohol, aldehyde, epoxide, indole, nitroalkane, and sulfide. Control reactions and mechanistic studies are consistent with the hypothesis that copper species are engaged in both the photochemistry and the key bond-forming step, which occurs through out-of-cage coupling of an alkyl radical.

| S-EPMC5624330 | biostudies-literature

Pyridone annulation via tandem Curtius rearrangement/6?-electrocyclization: total synthesis of (-)-lyconadin C.

Project description:A concise, enantioselective total synthesis of the Lycopodium alkaloid (-)-lyconadin C was achieved in 12 steps and high overall yield. Key features include construction of a luciduline congener through Mannich-type cyclization and a one-pot, tandem Curtius rearrangement/6?-electrocyclization to fashion the 2-pyridone system of lyconadin C.

| S-EPMC3788595 | biostudies-literature

A One-Pot Selective Synthesis of N-Boc Protected Secondary Amines: Tandem Direct Reductive Amination/N-Boc Protection.

Project description:A one-pot tandem direct reductive amination of aldehydes with primary amines resulting in N-Boc secondary amines using a (Boc)(2)O/sodium triacetoxyborohydride (STAB) system is reported. The tandem procedure is efficient, selective, and versatile, giving excellent yields of N-Boc protected secondary amines even in those cases where the products are prone to intramolecular lactamization.

| S-EPMC3404846 | biostudies-literature

Modification of Boc-Protected CAN508 via Acylation and Suzuki-Miyaura Coupling.

Project description:The cyclin-dependent kinase inhibitor, CAN508, was protected with di-tert-butyl dicarbonate to access the amino-benzoylated pyrazoles. The bromo derivatives were further arylated by Suzuki-Miyaura coupling using the XPhos Pd G2 pre-catalyst. The coupling reaction provided generally the para-substituted benzoylpyrazoles in the higher yields than the meta-substituted ones. The Boc groups were only utilized as directing functionalities for the benzoylation step and were hydrolyzed under conditions of Suzuki-Miyaura coupling, which allowed for elimination of the additional deprotection step.

| S-EPMC6017724 | biostudies-literature

Synthesis of Boc-protected bicycloproline.

Project description:The synthesis of a highly constrained quaternary carbocyclic α-amino acid, (+)-N-Boc-bicycloproline, has been achieved starting from sodium cyclopentadienylide. Key steps include a rhodium-catalyzed nitrenoid C-H insertion to install the tert-alkylamine and a ring-closing metathesis reaction to form the pyrrolidine ring.

| S-EPMC2808134 | biostudies-literature

An efficient new method for the synthesis of 3-[18 F]fluoro-4-aminopyridine via Yamada-Curtius rearrangement.

Project description:4-Aminopyridine is a clinically approved drug to improve motor symptoms in multiple sclerosis. A fluorine-18-labeled derivative of this drug, 3-[18 F]fluoro-4-aminopyridine, is currently under investigation for positron emission tomography (PET) imaging of demyelination. Herein, the Yamada-Curtius reaction has been successfully applied for the preparation of this PET radioligand with a better radiochemical yield and improved specific activity. The overall radiochemical yield was 5 to 15% (n = 12, uncorrected) with a specific activity of 37 to 148 GBq/μmol (end of synthesis) in a 90 minute synthesis time. It is expected that this 1 pot Yamada-Curtius reaction can be used to prepare similar fluorine-18-labeled amino substituted heterocycles.

| S-EPMC5992582 | biostudies-literature

The Curtius rearrangement of cyclopropyl and cyclopropenoyl azides. A combined theoretical and experimental mechanistic study.

Project description:A combined experimental and theoretical study addresses the concertedness of the thermal Curtius rearrangement. The kinetics of the Curtius rearrangements of methyl 1-azidocarbonyl cycloprop-2-ene-1-carboxylate and methyl 1-azidocarbonyl cyclopropane-1-carboxylate were studied by (1)H NMR spectroscopy, and there is close agreement between calculated and experimental enthalpies and entropies of activation. Density functional theory (DFT) calculations (B3LYP/6-311+G(d,p)) on these same acyl azides suggest gas phase barriers of 27.8 and 25.1 kcal/mol. By comparison, gas phase activation barriers for the rearrangement of acetyl, pivaloyl, and phenyl azides are 27.6, 27.4, and 30.0 kcal/mol, respectively. The barrier for the concerted Curtius reaction of acetyl azide at the CCSD(T)/6-311+G(d,p) level exhibited a comparable activation energy of 26.3 kcal/mol. Intrinsic reaction coordinate (IRC) analyses suggest that all of the rearrangements occur by a concerted pathway with the concomitant loss of N2. The lower activation energy for the rearrangement of methyl 1-azidocarbonyl cycloprop-2-ene-1-carboxylate relative to methyl 1-azidocarbonyl cyclopropane-1-carboxylate was attributed to a weaker bond between the carbonyl carbon and the three-membered ring in the former compound. Calculations on the rearrangement of cycloprop-2-ene-1-oyl azides do not support pi-stabilization of the transition state by the cyclopropene double bond. A comparison of reaction pathways at the CBS-QB3 level for the Curtius rearrangement versus the loss of N2 to form a nitrene intermediate provides strong evidence that the concerted Curtius rearrangement is the dominant process.

| S-EPMC2653059 | biostudies-literature

Ribosomal translocation: one step closer to the molecular mechanism.

Project description:Protein synthesis occurs in ribosomes, the targets of numerous antibiotics. How these large and complex machines read and move along mRNA have proven to be challenging questions. In this Review, we focus on translocation, the last step of the elongation cycle in which movement of tRNA and mRNA is catalyzed by elongation factor G. Translocation entails large-scale movements of the tRNAs and conformational changes in the ribosome that require numerous tertiary contacts to be disrupted and reformed. We highlight recent progress toward elucidating the molecular basis of translocation and how various antibiotics influence tRNA-mRNA movement.

| S-EPMC3010847 | biostudies-literature

Investigations of scope and mechanism of nickel-catalyzed transformations of glycosyl trichloroacetimidates to glycosyl trichloroacetamides and subsequent, atom-economical, one-step conversion to ?-urea-glycosides.

Project description:The development and mechanistic investigation of a highly stereoselective methodology for preparing ?-linked-urea neo-glycoconjugates and pseudo-oligosaccharides is described. This two-step procedure begins with the selective nickel-catalyzed conversion of glycosyl trichloroacetimidates to the corresponding ?-trichloroacetamides. The ?-selective nature of the conversion is controlled with a cationic nickel(II) catalyst, [Ni(dppe)(OTf)2 ] (dppe=1,2-bis(diphenylphosphino)ethane, OTf=triflate). Mechanistic studies have identified the coordination of the nickel catalyst with the equatorial C2 -ether functionality of the ?-glycosyl trichloroacetimidate to be paramount for achieving an ?-stereoselective transformation. A cross-over experiment has indicated that the reaction does not proceed in an exclusively intramolecular fashion. The second step in this sequence is the direct conversion of ?-glycosyl trichloroacetamide products into the corresponding ?-urea glycosides by reacting them with a wide variety of amine nucleophiles in presence of cesium carbonate. Only ?-urea-product formation is observed, as the reaction proceeds with complete retention of stereochemical integrity at the anomeric C?N bond.

| S-EPMC4136511 | biostudies-literature

Potassium Boc-protected secondary aminomethyltrifluoroborates: synthesis and Suzuki-Miyaura cross-coupling reactions.

Project description:Seven potassium Boc-protected secondary aminomethyltrifluoroborates were prepared in a standardized two-step process. The Suzuki-Miyaura cross-coupling reaction was studied with this new class of nucleophiles, and a large variety of aryl and hetaryl chlorides provided the desired products in good to excellent yields, thereby allowing easy access to secondary aminomethyl substructures.

| S-EPMC3447629 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

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