Diethyl isopropyl and isopropenyl phosphate via differently generated ketyl radicals of acetone reacting with diethyl phosphoric acid

Schole, J.; Schole, C.; Eikemeyer, J.; Krebs, Hans C.

doi:10.1016/s0040-4020(01)80823-1

Cited by 6 publications

(1 citation statement)

References 17 publications

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“…The depletion of 24 and the appearance of released diethyl phosphoric acid were determined from the NMR signals for the methylene protons of the phosphate ester and methylene hydrogens of diethyl phosphoric acid at δ 5.30 ppm and 3.88 ppm, respectively. The photolysis sample was spiked with an authentic sample of diethyl phosphoric acid synthesized from diethyl chlorophosphate [ 66 ]. A dramatic increase in the intensities of the new methylene and methyl signals at 3.88 and 1.19 ppm, respectively, confirmed the presence of diethyl phosphate.…”

Section: Methodsmentioning

confidence: 99%

Photorelease of phosphates: Mild methods for protecting phosphate derivatives

Senadheera¹,

Yousef²,

Givens³

2014

Beilstein J. Org. Chem.

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SummaryWe have developed a new photoremovable protecting group for caging phosphates in the near UV. Diethyl 2-(4-hydroxy-1-naphthyl)-2-oxoethyl phosphate (14a) quantitatively releases diethyl phosphate upon irradiation in aq MeOH or aq MeCN at 350 nm, with quantum efficiencies ranging from 0.021 to 0.067 depending on the solvent composition. The deprotection reactions originate from the triplet excited state, are robust under ambient conditions and can be carried on to 100% conversion. Similar results were found with diethyl 2-(4-methoxy-1-naphthyl)-2-oxoethyl phosphate (14b), although it was significantly less efficient compared with 14a. A key step in the deprotection reaction in aq MeOH is considered to be a Favorskii rearrangement of the naphthyl ketone motif of 14a,b to naphthylacetate esters 25 and 26. Disruption of the ketone-naphthyl ring conjugation significantly shifts the photoproduct absorption away from the effective incident wavelength for decaging of 14, driving the reaction to completion. The Favorskii rearrangement does not occur in aqueous acetonitrile although diethyl phosphate is released. Other substitution patterns on the naphthyl or quinolin-5-yl core, such as the 2,6-naphthyl 10 or 8-benzyloxyquinolin-5-yl 24 platforms, also do not rearrange by aryl migration upon photolysis and, therefore, do not proceed to completion. The 2,6-naphthyl ketone platform instead remains intact whereas the quinolin-5-yl ketone fragments to a much more complex, highly absorbing reaction mixture that competes for the incident light.

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Section: Methodsmentioning

confidence: 99%