Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

A regioselective etherification of pyridoxine via an ortho-pyridinone methide intermediate.

ABSTRACT: The catalyst-free, regioselective synthesis of 4'-O-substituted pyridoxine derivatives under solventless conditions is described. The methodology relies on the highly regioselective formation of the ortho-pyridinone methide from pyridoxine and subsequent oxa-Michael addition of alcohol nucleophiles. This methodology provides good to excellent yields for primary and secondary alcohols and moderate yields for tertiary alcohols.

SUBMITTER: Yazarians JA

PROVIDER: S-EPMC7111860 | biostudies-literature | 2017 Jun

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

A regioselective etherification of pyridoxine via an ortho-pyridinone methide intermediate.

Yazarians Jessica A JA Jiménez Brian L BL Boyce Gregory R GR

Tetrahedron letters 20170425 23

The catalyst-free, regioselective synthesis of 4'-O-substituted pyridoxine derivatives under solventless conditions is described. The methodology relies on the highly regioselective formation of the ortho-pyridinone methide from pyridoxine and subsequent oxa-Michael addition of alcohol nucleophiles. This methodology provides good to excellent yields for primary and secondary alcohols and moderate yields for tertiary alcohols. ...[more]

PMID: 32287448

Similar Datasets

Direct, iridium-catalyzed enantioselective and regioselective allylic etherification with aliphatic alcohols.

Project description: Not available

| S-EPMC2819336 | biostudies-literature

Copper-catalyzed regioselective ortho C-H cyanation of vinylarenes.

Project description:A copper-based catalytic technique for the regioselective ortho C-H cyanation of vinylarenes has been developed. This method provides an effective means for the selective functionalization of vinylarene derivatives. A copper-catalyzed cyanative dearomatization mechanism is proposed to account for the regiochemical course of this reaction.

| S-EPMC4127133 | biostudies-literature

3-Heterosubstituted Benzofurans from Hydroxyphenyl Propargyl Alcohols via ortho-Quinone Methide through a Metal-/Catalyst-Free Conjugate Addition/Oxy-Cyclization.

Project description:A facile route to 3-sulfonylated and 3-(1-benzotriazolyl)-benzofurans is achieved from readily available o-hydroxyphenyl propargyl alcohols (o-HPPAs) and bench-top sodium sulfonylates and benzotriazoles with no assistance of any reagent or catalyst. Bifunctional o-quinone methides (o-QMs) were the putative reaction intermediates ensued from dehydration of o-HPPA. Our study revealed that the o-QM was so choosy in selection of the nucleophiles for the key Michael addition reaction.

| S-EPMC6644147 | biostudies-literature

Stereoselective Synthesis of Atropisomeric Acridinium Salts by the Catalyst-Controlled Cyclization of ortho-Quinone Methide Iminiums.

Project description:Quinone methides are fundamental intermediates for a wide range of reactions in which catalyst stereocontrol is often achieved by hydrogen bonding. Herein, we describe the feasibility of an intramolecular Friedel-Crafts 6π electrocyclization through ortho-quinone methide iminiums stereocontrolled by a contact ion pair. A disulfonimide catalyst activates racemic trichloroacetimidate substrates and imparts stereocontrol in the cyclization step, providing a new avenue for selective ortho-quinone methide iminium functionalization. A highly stereospecific oxidation readily transforms the enantioenriched acridanes into rotationally restricted acridiniums. Upon ion exchange, the method selectively affords atropisomeric acridinium tetrafluoroborate salts in high yields and an enantioenrichment of up to 93 : 7 e.r. We envision that ion-pairing catalysis over ortho-quinone methide iminiums enables the selective synthesis of a diversity of heterocycles and aniline derivatives with distinct stereogenic units.

| S-EPMC9306694 | biostudies-literature

Regioselective Radical Arene Amination for the Concise Synthesis of ortho-Phenylenediamines.

Project description:The formation of arene C-N bonds directly from C-H bonds is of great importance and there has been rapid recent development of methods for achieving this through radical mechanisms, often involving reactive N-centered radicals. A major challenge associated with these advances is that of regiocontrol, with mixtures of regioisomeric products obtained in most protocols, limiting broader utility. We have designed a system that utilizes attractive noncovalent interactions between an anionic substrate and an incoming radical cation in order to guide the latter to the arene ortho position. The anionic substrate takes the form of a sulfamate-protected aniline and telescoped cleavage of the sulfamate group after amination leads directly to ortho-phenylenediamines, key building blocks for a range of medicinally relevant diazoles. Our method can deliver both free amines and monoalkyl amines allowing access to unsymmetrical, selectively monoalkylated benzimidazoles and benzotriazoles. As well as providing concise access to valuable ortho-phenylenediamines, this work demonstrates the potential for utilizing noncovalent interactions to control positional selectivity in radical reactions.

| S-EPMC8251697 | biostudies-literature

Stereodivergent construction of cyclic ethers by a regioselective and enantiospecific rhodium-catalyzed allylic etherification: total synthesis of gaur acid.

Project description: Not available

| S-EPMC1479310 | biostudies-literature

Alcohol Etherification via Alkoxy Radicals Generated by Visible-Light Photoredox Catalysis.

Project description:A mechanistically divergent method is described that, employing a commercially available hypervalent iodine(III) reagent, generates alkoxy radicals from 1°, 2°, and 3° alcohols and allows their use in the functionalization of C(sp3)-H and C(sp2)-H bonds. This visible-light photoredox catalysis produces alkyl ethers via 1,5/6-hydrogen atom transfer or aryl ethers via 1,5-addition. This mild methodology provides a practical strategy for the synthesis of acetals, orthoesters, tetrahydrofurans, and chromanes.

| S-EPMC7653678 | biostudies-literature

Directed regioselective ortho,ortho'-magnesiations of aromatics and heterocycles using sBu2Mg in toluene.

Project description:Aryl azoles are ubiquitous as bioactive compounds and their regioselective functionalization is of utmost synthetic importance. Here, we report the development of a toluene-soluble dialkylmagnesium base sBu2Mg. This new reagent allows mild and regioselective ortho-magnesiations of various N-arylated pyrazoles and 1,2,3-triazoles as well as arenes bearing oxazoline, phosphorodiamidate or amide directing groups. The resulting diarylmagnesium reagents were further functionalized either by Pd-catalyzed arylation or by trapping reactions with a broad range of electrophiles (aldehydes, ketones, allylic halides, acyl chlorides, Weinreb amides, aryl halides, hydroxylamine benzoates, terminal alkynes). Furthermore, several double ortho,ortho'-magnesiations were realized in the case of aryl oxazolines, N-aryl pyrazoles as well as 2-aryl-2H-1,2,3-triazoles by simply repeating the magnesiation/electrophile trapping sequence allowing the preparation of valuable 1,2,3-functionalized arenes.

| S-EPMC8221067 | biostudies-literature

Electrochemical oxidation-induced etherification via C(sp3)?H/O?H cross-coupling.

Project description:Direct electrochemical construction of C?O bonds through C(sp3)?H functionalization still remains fundamentally challenging. Here, electrochemical oxidation-induced benzylic and allylic C(sp3)?H etherification has been developed. This protocol not only offers a practical strategy for the construction of C?O bonds using nonsolvent amounts of alcohols but also allows direct electrochemical benzylic and allylic C(sp3)?H functionalization in the absence of transition metal catalysis. A series of alcohols and benzylic and allylic C(sp3)?H compounds were compatible with this transformation. Mechanistically, the generation of aryl radical cation intermediates is the key to this C(sp3)?H etherification, as evidenced by radical probe substrate (cyclopropane ring opening) and electron paramagnetic resonance experiments.

| S-EPMC7228760 | biostudies-literature

Antineoplastic Isoflavonoids Derived from Intermediate ortho-Quinone Methides Generated from Mannich Bases.

Project description:The regioselective condensations of various 7-hydroxyisoflavonoids with bis(N,N-dimethylamino)methane in a Mannich reaction provided C-8 N,N-dimethylaminomethyl-substituted isoflavonoids in good yield. Similar condensations of 7-hydroxy-8-methylisoflavonoids led to the C-6-substituted analogs. Thermal eliminations of dimethylamine from these C-6 or C-8 N,N-dimethylaminomethyl-substituted isoflavonoids generated ortho-quinone methide intermediates within isoflavonoid frameworks for the first time. Despite other potential competing outcomes, these ortho-quinone methide intermediates trapped dienophiles including 2,3-dihydrofuran, 3,4-dihydro-2H-pyran, 3-(N,N-dimethylamino)-5,5-dimethyl-2-cyclohexen-1-one, 1-morpholinocyclopentene, and 1-morpholinocyclohexene to give various inverse electron-demand Diels-Alder adducts. Several adducts derived from 8-N,N-dimethylaminomethyl-substituted isoflavonoids displayed good activity in the 1-10 μm concentration range in an in vitro proliferation assay using the PC-3 prostate cancer cell line.

| S-EPMC4818953 | biostudies-literature