Browse
Submit Data
Databases
API
Help

Dataset Information

28 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Phosphine-Catalyzed Intramolecular Cyclizations of ?-Nitroethylallenoates Forming (Z)-Furanone Oximes.

ABSTRACT: A novel and efficient phosphine-catalyzed intramolecular cyclization of ?-nitroethylallenic esters is reported. This process appears to be practical for the stereoselective syntheses of (Z)-furan-2(3H)-one oxime derivatives in excellent yields. Mechanistically, the reaction involves a phosphine-catalyzed Michael addition of an alkylideneazinate and rearrangement of the cyclic nitronate to the ?-nitrosodihydrofuran.

SUBMITTER: Zhou QF

PROVIDER: S-EPMC4922534 | biostudies-literature | 2016 Jun

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Publications

Phosphine-Catalyzed Intramolecular Cyclizations of α-Nitroethylallenoates Forming (Z)-Furanone Oximes.

Zhou Qing-Fa QF Zhang Kui K Cai Lingchao L Kwon Ohyun O

Organic letters 20160527 12

A novel and efficient phosphine-catalyzed intramolecular cyclization of α-nitroethylallenic esters is reported. This process appears to be practical for the stereoselective syntheses of (Z)-furan-2(3H)-one oxime derivatives in excellent yields. Mechanistically, the reaction involves a phosphine-catalyzed Michael addition of an alkylideneazinate and rearrangement of the cyclic nitronate to the α-nitrosodihydrofuran. ...[more]

PMID: 27232451

Similar Datasets

Enantioselective cyclizations of silyloxyenynes catalyzed by cationic metal phosphine complexes.

Project description:The discovery of complementary methods for enantioselective transition metal-catalyzed cyclization with silyloxyenynes has been accomplished using chiral phosphine ligands. Under palladium catalysis, 1,6-silyloxyenynes bearing a terminal alkyne led to the desired five-membered ring with high enantioselectivities (up to 91% ee). As for reactions under cationic gold catalysis, 1,6- and 1,5-silyloxyenynes bearing an internal alkyne furnished the chiral cyclopentane derivatives with excellent enantiomeric excess (up to 94% ee). Modification of the substrate by incorporating an ?,?-unsaturation led to the discovery of a tandem cyclization. Remarkably, using silyloxy-1,3-dien-7-ynes under gold catalysis conditions provided the bicyclic derivatives with excellent diastereo- and enantioselectivities (up to >20:1 dr and 99% ee).

| S-EPMC3279184 | biostudies-literature

Gold-Catalyzed Intramolecular Cyclizations of Cyclopropenes with Propargylic Esters.

Project description:Homogeneous gold catalysts are interesting as they can act as potent carbophilic Lewis acids to activate the ? bonds of alkynes, allenes, and alkenes. Many impressive applications for the formation of C-C or C-heteroatom bonds have been found due to the excellent functional group compatibility of these catalysts and the air and moisture tolerance of their reactions. Here, we have developed gold-catalyzed novel intramolecular cycloisomerizations of nitrogen or oxygen-tethered cyclopropenes with propargylic esters. The reaction proceeded through different pathways according to different substituent styles, affording 5-azaspiro[2.5]oct-7-enes and bicyclo[4.1.0]heptanes.

| S-EPMC4906491 | biostudies-literature

Intramolecular rhodium-catalyzed [2+2+2] cyclizations of diynes with enones.

Project description:The Rh(I)-catalyzed inter- and intramolecular [2+2+2] cyclization of diynes with alpha,beta-unsaturated enones proceeds with microwave promotion in good yields. This chemistry was applied to the synthesis of (-)-alcyopterosin I.

| S-EPMC2739116 | biostudies-literature

Silver(I)-Catalyzed Intramolecular Cyclizations of Epoxide-Propargylic Esters to 1,4-Oxazine Derivatives.

Project description:An interesting silver(I)-catalyzed, one-pot intramolecular cyclization of epoxide-propargylic esters is described. A variety of 1,4-oxazine derivatives were obtained through a novel domino sequence, including three-membered ring-opening, 3,3-sigmatropic rearrangement, 6-exo-cycloisomerization and subsequent intramolecular elimination in moderate yields under mild conditions.

| S-EPMC5288764 | biostudies-literature

Phosphine-catalyzed enantioselective intramolecular [3+2] annulations to generate fused ring systems.

Project description:Substantial progress has been described in the development of asymmetric variants of the phosphine-catalyzed intermolecular [3+2] annulation of allenes with alkenes; however, there have not been corresponding advances for the intramolecular process, which can generate a higher level of complexity (an additional ring and stereocenter(s)). In this study, we describe the application of chiral phosphepine catalysts to address this challenge, thereby providing access to useful scaffolds that are found in bioactive compounds, including diquinane and quinolin-2-one derivatives, with very good stereoselectivity. The products of the [3+2] annulation can be readily transformed into structures that are even more stereochemically rich. Mechanistic studies are consistent with β addition of the phosphepine to the allene being the turnover-limiting step of the catalytic cycle, followed by a concerted [3+2] cycloaddition to the pendant olefin.

| S-EPMC4433041 | biostudies-literature

Asymmetric palladium-catalyzed intramolecular alpha-arylation of aldehydes.

Project description: Not available

| S-EPMC2748771 | biostudies-literature

Rhodium-catalyzed intramolecular C-H insertion of alpha-aryl-alpha-diazo ketones.

Project description:Direct diazo transfer proceeds smoothly with alpha-aryl ketones. The derived alpha-aryl-alpha-diazo ketones cyclize efficiently with Rh catalysis to give the corresponding alpha-aryl cyclopentanones.

| S-EPMC3248813 | biostudies-literature

Phosphine-catalyzed β'-umpolung addition of nucleophiles to activated α-alkyl allenes.

Project description:Highly functionalized alkenes can be prepared through phosphine-catalyzed β'-umpolung additions of nucleophiles (carbon-, oxygen-, nitrogen-, and sulfur-centered) to activated α-disubstituted allenes, providing many potentially useful synthetic intermediates in good to excellent yields, often with high levels of stereoselectivity for the product olefin geometry. Various substitution patterns around the allene are compatible with the process, showcasing the synthetic utility of allenes under the conditions of nucleophilic phosphine catalysis.

| S-EPMC3094471 | biostudies-literature

Phosphine-catalyzed intramolecular ?-umpolung addition of ?-aminoalkylallenic esters: facile synthesis of 3-carbethoxy-2-alkyl-3-pyrrolines.

Project description:An array of N-tosylated ?-aminoalkylallenic esters was prepared and their cyclization under the influence of nucleophilic phosphine catalysts was explored. The ?-aminoalkylallenic esters were prepared through aza-Baylis-Hillman reactions or novel DABCO-mediated decarboxylative rearrangements of allenylic carbamates. Conversion of these substrates to 3-carbethoxy-2-alkyl-3-pyrrolines was facilitated through Ph(3)P-catalyzed intramolecular ?-umpolung addition.

| S-EPMC4128507 | biostudies-literature

Enantioselective Synthesis of α,α-Disubstituted Lactones via a Chiral Bronsted Acid Catalyzed Intramolecular Cyclization.

Project description: Not available

| S-EPMC5198840 | biostudies-literature