The O,O-dibenzyl-S-glycosyl phosphothioite derived from 3,4,6-tri-O-acetyl-2-acetamido-2-deoxy-1-thio-alpha-D-glucopyranose rearranges under the influence of triethylborane and air to provide the corresponding 1-C-pyranosyl-O,O-dibenzylphosphonothioate, a new type of carbohydrate derivative. The isomeric beta phosphothioite is compared, and evidence of a radical chain mechanism for the Pudovik rearrangement is presented.
Download full-text PDF |
Source |
---|---|
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2712301 | PMC |
http://dx.doi.org/10.1016/j.tetlet.2007.01.081 | DOI Listing |
J Org Chem
October 2024
Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India.
An approach involving the use of a bifunctional aminocatalyst containing Brønsted base and iminium activation sites for asymmetric multicomponent reactions involving [1,2]-phospha-Brook rearrangement has yet to be realized. Herein, we present an aminocatalytic enantioselective conjugate addition of α-phosphonyloxy enolates formed [1,2]-phospha-Brook rearrangement to α,β-unsaturated ketones. The methodology unfolds a simple one-pot operation consisting of a robust additive-free catalytic system providing a series of oxindole derivatives having two contiguous stereocenters in high yields with excellent stereoselectivities.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
May 2024
Key Laboratory of Green Chemistry & Technology of Ministry of Education, College of Chemistry, Sichuan University, 29 Wangjiang Road, Chengdu, 610064, P. R. China.
Despite the significance of chiral allene skeletons in catalysis, organic synthesis and medicinal chemistry et al., there is a scarcity of reports on axially chiral allenyl phosphorus compounds. Here, we disclosed an efficient and straightforward cascade reaction between ethynyl ketones and phosphine oxides, resulting in a broad array of trisubstituted allenes incorporating a phosphorus moiety in high yields with excellent stereoselectivities facilitated by peptide-mimic phosphonium salt (PPS) catalysis, Additionally, comprehensive series of mechanistic experiments have been conducted to elucidate that this cascade reaction proceeds via an asymmetric Pudovik addition reaction followed by a subsequent phospha-Brook rearrangement that occurs concomitantly with kinetic resolution, representing a stereospecific rearrangement and protonation process facilitating central-to-axial chirality transfer in a cascade manner.
View Article and Find Full Text PDFMolecules
August 2023
Department of Organic Chemistry and Technology, Faculty of Chemical Technology and Biotechnology, Budapest University of Technology and Economics, 1521 Budapest, Hungary.
New hydroxy-methylenebisphosphonic derivatives were prepared with different P-functions. The outcome of the reaction of α-oxophosphonates (YC(O)P(O)(OR)) and dialkyl phosphites or diarylphosphine oxides depended on the Y substituent of the oxo-compound, the nature of the P-reagent and the amount of the diethylamine catalyst. Starting from dimethyl α-oxoethylphosphonate, in the presence of 5% of diethylamine, the corresponding Pudovik adduct was the single product.
View Article and Find Full Text PDFOrg Lett
September 2023
Key Laboratory of Green Chemistry and Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, China.
The multicomponent catalytic asymmetric Pudovik addition/[1,2]-phospha-Brook rearrangement/Michael reaction sequence of isatins, phosphites, and 4-oxobutenoates was realized. A series of oxindole derivatives containing two contiguous stereocenters was obtained in high yields and excellent stereoselectivities (up to >99% yield, >95:5 dr, >99% ee) using a chiral Lewis acid catalyst. A possible catalytic model is presented to illustrate the stereocontrol.
View Article and Find Full Text PDFJ Org Chem
July 2023
Key Laboratory of Green Chemistry & Technology, Ministry of Education, College of Chemistry, Sichuan University, Chengdu 610064, China.
Pudovik addition/[1,2]-phospha-Brook rearrangement as an efficient tool for generation of anionic nucleophiles is an attractive strategy for the construction of C-C bonds in organic synthesis. Herein, we report organocatalytic 1,6-conjugate addition of -quinone methides utilizing Pudovik addition/[1,2]-phospha-Brook rearrangement. Chiral guanidine-sulfonamide catalyzed the three-component reaction efficiently, providing biologically active oxindole/biaryl/phosphorus-based structures in high yields with excellent diastereo- and enantioselectivities.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!