1993
DOI: 10.1002/rcm.1290070112
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Cyclic boronates in the mass spectrometry of ecdysteroids

Abstract: For the structural elucidation of ecdysteroids a reaction with phenylboronic acid has been employed. This reaction takes place exclusively on the C20,C22 diol moiety, thus facilitating fast and easy detection of this moiety in the molecule of ecdysteroid. This derivatization also redirects fragmentation to C17/C20 bond cleavage with charge retention on both fragments enabling assessment of the structure both of the steroid nucleus and of the side-chain. Possible reaction of phenylboronic acid with the diol moi… Show more

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Cited by 9 publications
(2 citation statements)
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“…As reported earlier, an enolization of the C6 carbonyl functionality of polypodine B (5-b-20-dihydroxyecdysone) 7 was determined by the formation of a bis-adduct from the reaction with phenylboronic acid, where the second adduct was found to be formed on the C5 OH and enolized C6 carbonyl. 20 In the H/D exchange experiment, polypodine B 7 exchanges additional hydrogen like other ecdysteroids to 0.6% in positive and 8.4% in negative mode. On the other hand, 22-oxo-20-hydroxyecdysone 3 shows much higher additional exchange (7.8% in positive and 23.6% in negative mode), pointing to a higher propensity of the alicyclic C22 carbonyl to enolization than the cyclic C6 enone (Scheme 2).…”
Section: Resultsmentioning
confidence: 96%
“…As reported earlier, an enolization of the C6 carbonyl functionality of polypodine B (5-b-20-dihydroxyecdysone) 7 was determined by the formation of a bis-adduct from the reaction with phenylboronic acid, where the second adduct was found to be formed on the C5 OH and enolized C6 carbonyl. 20 In the H/D exchange experiment, polypodine B 7 exchanges additional hydrogen like other ecdysteroids to 0.6% in positive and 8.4% in negative mode. On the other hand, 22-oxo-20-hydroxyecdysone 3 shows much higher additional exchange (7.8% in positive and 23.6% in negative mode), pointing to a higher propensity of the alicyclic C22 carbonyl to enolization than the cyclic C6 enone (Scheme 2).…”
Section: Resultsmentioning
confidence: 96%
“…The derivatization technique was extended to negative-ion liquid secondary ion mass spectrometry (LSIMS) where it was presumed that mixtures of boronic acids and certain trifunctional nucleophilic compounds (e.g., glycerol) reacted in situ to produce negatively charged boronate complexes which were subsequently sputtered from the liquid surface and mass analyzed . This approach has been used to study a number of polyfunctional nucleophilic compounds as their corresponding boronate esters. In situ derivatization was also used to characterize 20-hydroxyecdysteroids as their phenylboronate esters by positive-ion LSIMS, which seems to belie the mechanism of direct boronate complex ion formation (“pre-ionization”) postulated by Rose et al Subsequently, there have been broader negative-ion LSIMS studies of boron-containing compounds. The presumption that pre-ionization of a boronic acid to a boronate complex anion occurs in situ may account for the preferential use of negative LSIMS mode in conjunction with the derivatization technique. However, this assumption has apparently precluded the investigation of the positive-ion LSIMS of boronic acids and esters; no positive-ion LSIMS studies of boronic acids have been reported.…”
mentioning
confidence: 99%