Synthesis and E-Beam-Mediated Gas Phase Fragmentation of Thiol-Containing Furoxans for Nanopatterned Alkyne Formation on Gold Surface

Abstract

Furoxanthiols PFT and BPFT possessing thiomethyl or thiobenzyl groups in the furoxan ring were designed and synthesized as potential light-sensitive alkyne precursors on a gold surface. The synthesis of thiofuroxans PFT and BPFT was performed from the corresponding halofuroxans 1b and 2c, respectively, by the substitution with potassium thioacetate in ethyl acetate/ethanol or DMF, followed by basic hydrolysis as the key reactions. Electron-beammediated fragmentation of furoxans 1c and 2d in a mass spectrometer afforded the corresponding aryl alkyne fragments, with the evolution of NO in high preference. In the cases of thiofuroxans PFT and BPFT, carbon-sulfur bond cleavage was observed as a representative fragmentation, producing M-SH and M-SAc peaks, which competed with the release of NO. In the fragmentation of mono-aryl furoxan 1c, the release of molecule of NO was predominately observed to produce an M-NO fragment as a base peak by the formation of trimembered thiiranium or azirine intermediate.

The mechanism of water loss from protonated cathinones

“…To the best of our knowledge, only Qian et al have proposed the formation of azirine structure for the [M + H − H 2 O] + ion of one cathinone, namely mexedrone . On the contrary, the formation of azirine‐ring‐containing ions has been proposed for fragmentation processes of N‐heterocyclic compounds that occurred under EI conditions, under fast atom bombardment (FAB) conditions, and under ESI conditions …”

“…[15][16][17][18][19] This mechanism (scheme 2) is disputable because (a) it indicates that the loss of H 2 O occurs also for those compounds that contain Table S1 (supporting information). In the experimental part, it is explained 21 On the contrary, the formation of azirine-ring-containing ions has been proposed for fragmentation processes of N-heterocyclic compounds that occurred under EI conditions, [22][23][24][25] under fast atom bombardment (FAB) conditions, 26 and under ESI conditions. 27 We also obtained the product ion spectra of Figure 1), and the calculated exact mass is 147.0810, so the mass accuracy is −6.1 ppm.…”