Enyne alcohols can react as precursors of either dienes or dienophiles with different substrates after hydroxylation and isomerization by gold catalysis. As such, oxa-bridged tricyclo[5.2.2.02,6]-undec-8-ene-3,5-dione derivatives have been obtained by the Diels–Alder reaction and tetrahydro-1H-furo[3,4-c]pyran derivatives could be accessed by the hetero-Diels–Alder cycloaddition.

An unexpected copper(II)-catalyzed three-component reaction of quinazoline-3-oxide, alkylidenecyclopropane and water under mild conditions is reported. This transformation including [3+2] cycloaddition and intramolecular rearrangement leads to N-(2-(5-oxa-6-azaspiro[2.4]hept-6-en-7-yl)phenyl)formamides in good yields.

Abstract Quinobenzazepines are useful in medicinal chemistry, but their synthesis is very challenging. Herein, we designed and synthesized a range of multi‐functional chalcone‐based quinolinium salts; synthetic application the rapid straightforward construction quinobenzazepines was successfully explored. A wide oxa‐bridged quinobenzazepine polycycles were afforded serendipitously through dearo...

Theoretical and experimental studies of the reaction of isoxazoles with diazo compounds show that the formation of 2H-1,3-oxazines proceeds via the formation of (3Z)-1-oxa-5-azahexa-1,3,5-trienes which undergo a 6π-cyclization. The stationary points corresponding to the probable reaction intermediates, isoxazolium N-ylides, were located by DFT calculations at the B3LYP/6-31G(d) level only for d...

It has been suggested that carcinogenesis associated with chronic inflammation involves DNA damage by nitric oxide (NO) and other reactive species secreted from macrophages and neutrophils. The guanine moiety of DNA reacts with NO, yielding two major deamination products: xanthine (Xan) and oxanine (Oxa). Oxa reacts further with polyamines and DNA binding proteins to form cross-link adducts. In...

The bismuth-mediated two-component hemiacetal oxa-conjugate addition of γ-hydroxy-α,β-unsaturated ketones with paraformaldehyde affords anti-4,5-disubstituted-1,3-dioxolanes in an efficient and stereoselective manner. The reaction provides a practical, inexpensive and atom-economical approach to these types of heterocycles, which represent useful intermediates for target-directed synthesis and ...

Our study determines the resistance gene profile of a set of Acinetobacter baumannii hospital isolates. A. baumannii is responsible for nosocomial outbreaks and sporadic infections. We extracted and PCR amplified bacterial DNA isolated from patients with ages below 60 years (23.36%) and above 60 years (76.64%). Most of the patients were admitted in the ICU (36.13%) and pneumology departments (2...

Oxanine (Oxa) is a deaminated base lesion derived from guanine in which the N(1)-nitrogen is substituted by oxygen. This work reports the mutagenicity of oxanine as well as oxanine DNA glycosylase (ODG) activities in mammalian systems. Using human DNA polymerase beta, deoxyoxanosine triphosphate is only incorporated opposite cytosine (Cyt). When an oxanine base is in a DNA template, Cyt is effi...