133435-76-4Relevant articles and documents
Gas-phase fragmentation of γ-lactone derivatives by electrospray ionization tandem mass spectrometry
Crotti, Antonio E. M.,Bronze-Uhle, Erika S.,Nascimento, Paulo G. B. D.,Donate, Paulo M.,Galembeck, Sergio E.,Vessecchi, Ricardo,Lopes, Norberto P.
, p. 1733 - 1741 (2009)
Fragmentation reactions of β-hydroxymethyl-, β-acetoxymethyl- and β-benzyloxymethyl-butenolides and the corresponding γ-butyrolactones were investigated by electrospray ionization tandem mass spectrometry (ESI-MS/MS) using collision-induced dissociation (CID). This study revealed that loss of H2O [M+H-18]+ is the main fragmentation process for β-hydroxymethylbutenolide (1) and β-hydroxymethyl-γ- butyrolactone (2). Loss of ketene ([M+H-42]+) is the major fragmentation process for protonated β-acetoxymethyl-γ-butyrolactone (4), but not for β-acetoxymethylbutenolide (3). The benzyl cation (m/z 91) is the major ion in the ESI-MS/MS spectra of β-benzyloxymethylbutenolide (5) and β-benzyloxymethyl-γ-butyrolactone (6). The different side chain at the β-position and the double bond presence afforded some product ions that can be important for the structural identification of each compound. The energetic aspects involved in the protonation and gas-phase fragmentation processes were interpreted on the basis of thermochemical data obtained by computational quantum chemistry. Copyright
Application of the palladium-catalysed norbornene-assisted catellani reaction towards the total synthesis of (+)-linoxepin and isolinoxepin
Qureshi, Zafar,Weinstabl, Harald,Suhartono, Marcel,Liu, Hongqiang,Thesmar, Pierre,Lautens, Mark
, p. 4053 - 4069 (2014/07/08)
Our ongoing effort towards the development of highly selective transition-metal-catalysed C-H activation processes has led to the expansion of the Catellani reaction. In a Pd0/PdII/Pd IV-catalysed domino reaction, an aryl iodide, alkyl iodide and tert-butyl acrylate were combined to synthesize the carbon framework of the novel lignan (+)-linoxepin. The enantioselective synthesis highlights the work accomplished in our group and provides an excellent procedure for the reliable and scalable synthesis of architecturally complex scaffolds. This report outlines the synthetic approaches towards this interesting class of biologically active molecules. After the key Catellani/Heck reaction, our synthesis features a Leimeux-Johnson oxidation and a titanium tetrachloride mediated aldol condensation. Finally, a tuneable Mizoroki-Heck reaction was performed to furnish not only the natural product (+)-linoxepin but also its isoform, which we have named isolinoxepin. The enantioselective total synthesis of the natural product (+)-linoxepin has been accomplished in eight steps starting from commercial materials. The key Pd-catalysed Catellani step served to combine aryl iodide, alkyl iodide and tert-butyl acrylate in a domino sequence. By tuning the final Heck reaction, both the natural product and its structural isomer were synthesized. Copyright
