A mechanistic study of fragmentation of deprotonated N,2‐diphenyl‐acetamides in electrospray ionization tandem mass spectrometry

Abstract

The characteristic fragment ions of deprotonated N,2-diphenylacetamides were proposed to be produced via an ion-neutral complex mechanism, which was proved by deuterium-labeling experiments, theoretical calculations and substituent effects.

Benzyl anion transfer in the fragmentation of N-(phenylsulfonyl)-benzeneacetamides: a gas-phase intramolecular SNAr reaction

“…This route is similar to that discussed by Lu et al 30 On the other hand, calculations show that the product ion C.o, resulting from the ortho-channel, stabilizes the negative charge by cyclization (as shown in parentheses), whereby it is placed in an extremely deep potential well compared with the meta-Scheme 3 Gas-phase fragmentation reaction mechanisms proposed for the INC-involved product ions from deprotonated compound 1; ortho-position selected as an example for clear illustration; the italic suffix represents the reaction position of the phenyl ring. As proposed in the upper reaction route in Scheme 3, within INC-1, the benzyl anion captures an ortho proton from the neutral counterpart leading to the formation of C.o.…”

“…The benzyl anion is so highly electron-rich that it can act as an electron donor to undergo a single electron transfer reaction. 30 In view of its well-known nucleophilicity, here we question if it could undergo intramolecular transfer to achieve gas-phase nucleophilic substitution reactions. 30 In view of its well-known nucleophilicity, here we question if it could undergo intramolecular transfer to achieve gas-phase nucleophilic substitution reactions.…”

Friedel‐Crafts dealkylation reaction mediated by a stereoselective proton transfer in the fragmentation of protonated cyclic indolyl α‐amino esters

“…Ion‐neutral complexes (INCs) frequently exist as reactive intermediates in gas‐phase ionic reactions, in which various chemical reactions including proton transfer reactions may occur either between the two partners or inside the ion moiety alone prior to the final separation . Since the proton affinities of cyclic N ‐sulfonyl ketimino esters ( f ) are significantly higher than those of indoles ( e ) based on theoretical calculations shown in Table , they can easily snatch a proton from the C 4 atom protonated indoles in the ion‐neutral complex INC‐2 to form INC‐3.…”

Ortho‐hydroxyl effect and proton transfer via ion–neutral complex: the fragmentation study of protonated imine resveratrol analogues in mass spectrometry

“…Ion‐neutral complexes (INCs) are important intermediates and widely observed in unimolecular fragmentation reactions in mass spectrometry . An INC consists the ionic fragment and neutral species that are binding together by electrostatic interactions and maintain their individual mobility.…”

“…[5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] Ion-neutral complexes (INCs) are important intermediates and widely observed in unimolecular fragmentation reactions in mass spectrometry. [17,[21][22][23][24][25][26][27][28][29][30][31][32][33][34] An INC consists the ionic fragment and neutral species that are binding together by electrostatic interactions and maintain their individual mobility. In this temporary system, various chemical reactions can take place before its final decomposition.…”