Histidine is an important natural amino acid, involved in many relevant biological processes, which, because of its physical properties, proved difficult to characterize experimentally in its neutral form. In this work, neutral histidine has been generated in the gas phase by laser ablation of solid samples and its N(ε)H tautomeric form unraveled through its rotational spectrum. The quadrupole ...

The idea of the enol form of nucleotides being responsible for the formation of some noncanonical pairs was put forward by Watson and Crick in their first paper on DNA structure [1]. In the context of this hypothesis, the GU pair may contain either the enol form of uracil and the keto form of guanine or the enol form of guanine and the keto form of uracil. Later, in 1966, Francis Crick proposed...

Viral lethal mutagenesis is a strategy whereby the innate immune system or mutagenic pool nucleotides increase the error rate of viral replication above the error catastrophe limit. Lethal mutagenesis has been proposed as a mechanism for several antiviral compounds, including the drug candidate 5-aza-5,6-dihydro-2'-deoxycytidine (KP1212), which causes A-to-G and G-to-A mutations in the HIV geno...

Photodecarboxylation of p-benzoylphenylacetic acid in aqueous solution produces the elongated enol 5, whose strength as an oxygen acid (pQ(E/a)= 7.67) makes it more acidic than simple enol analogs by several orders of magnitude.

Key words palladium catalysis - silyl enol ethers α,β-unsaturated carbonyls

Abstract Tautomerism is one of the most important phenomena to consider when designing biologically active molecules. In this work, we use NMR spectroscopy, IR, and X-ray analysis as well quantum-chemical calculations in gas phase a solvent study tautomerism 1- (2-, 3- 4-pyridinecarbonyl)-4-substituted thiosemicarbazide derivatives. The tautomer containing both carbonyl thione groups turned out...

A novel alkyl chain-functionalized manganese complex with dioxolene ligands shows a bimodal three-membered valence tautomerism, one of which synchronizes with a cooperative solid-melt phase transition and the other occurs in the melt noncooperatively.

We report a state-of-the-art spectroscopic study of an archetypical barbaralone, conclusively revealing the valence tautomerism phenomena for this bistable molecular system. The two distinct 1- and 5-substituted tautomers have been isolated in supersonic expansion first time successfully characterized by high-resolution rotational spectroscopy. This work provides irrefutable experimental eviden...

The titular compound was characterized for the first time using a full range of spectroscopic methods, including UV, IR, 1H, and 13C NMR spectra. In solution, all methods showed keto–enol equilibrium strongly shifted to enol form. X-ray structures determined simple 2-oxosuccinates only form packed as hydrogen-bonded dimer stacks.