Tandem Β-elimination Research Articles

Selective enrichment tandem β-elimination assisted strategy for N-phosphorylation analysis

N-phosphorylation modifications are crucial for prokaryotic signal transduction and verified as intermediate for several metabolic enzymes, yet the landscape of N-phosphorylation remains an obstacle due to the lack of effective identification strategies. One of the difficulties derives from the labile phosphoramidate bond (P–N) under acidic conditions, making it easily hydrolyze during the routine analysis. Meanwhile, O-phosphopeptides influence the accurate identification of N-phosphorylation sites during mass spectrometry (MS) analysis. Herein, a selective enrichment tandem β-elimination assisted identification (abbreviated as EnaBe) strategy was established to address the difficulties. Firstly, N-phosphoproteins could be captured within 10 min by SiO2@DpaZn microspheres under neutral conditions, which was benefited from rapid mass transfer. Secondly, the β-elimination efficiency could reach over 92% within 3 h under the optimized condition, and MS signals of N-phosphopeptides were significantly enhanced by integrating the β-elimination treatment. Finally, N-phosphoproteins from E. coli lysates were analyzed by EnaBe approach and 16 N-phosphoproteins with high confidence were identified. Furthermore, functional analysis showed that the proteins played vital roles in phosphorylation process and bacterial primary metabolic processes including glucose, purine and ADP metabolism. All above results demonstrated the superiority of the EnaBe strategy.

Efficient and Benign One-Pot Conversion of N-Tosyl-1,4,5,6-tetrahydropyrimidines to Pyrimidines via Tandem β-Elimination and Aromatization

An efficient, mild, benign, and practical method for one-pot conversion of N-tosyl-1,4,5,6-tetrahydropyrimidines into pyrimidines is discussed in detail. In this method, N-tosyl-1,4,5,6-tetrahydropyrimidines are first prepared via N-tosylation of tetrahydropyrimidines with TsCl and then treated with 1.5 equivalents of NaOH in dimethylsulfoxide (DMSO) under air at 60 °C to afford corresponding pyrimidines in 70–95% yields via cascade β-elimination and aromatization. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resources: Full experimental and spectral details.]

Samarium Diiodide Promoted Tandem β-Elimination and Cross-Pinacol Coupling: A New Access to 1-Vinyl-1,2-diols with Two Adjacent Quaternary Carbon Centers

A samarium diiodide promoted tandem β-elimination/cross-pinacol coupling was developed. A series of novel 1-vinyl-1,2-diols with two adjacent quaternary carbon centers were obtained in moderate to good yields. Possible reaction pathways are proposed.

Synthesis of N-substituted iminosugars from 2′-carbonyl-C-glycofuranosides

Under basic conditions 2′-carbonyl 5-N-substituted-C-glycofuranosides undergo a tandem β-elimination and intramolecular hetero-Michael addition to form N-substituted iminosugar derivatives in good to excellent yields.

Synthesis of thio- C-glycosides from 2′-carbonylalkyl C-glycosides by a tandem β-elimination and intramolecular hetero-Michael addition

2′-Carbonyl 5- S-acetyl- C-glycofuranosides and 2′-carbonyl 4- S-acetyl- C-glycopyranosides were converted in good yields to respective 5-thio- C-glycopyranosides and 4-thio- C-glycofuranosides under base treatment. The transformation was resulted from β-elimination on 2′-carbonyl C-glycoside to form α,β-conjugated aldehyde (or ketone) and following intramolecular hetero-Michael addition by the thiol group.