- Organocatalytic selective benzoylation of alcohols with trichloromethyl phenyl ketone: Inverse selectivity in benzoylation of alcohols containing phenol or aromatic amine functionality
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Trichloromethyl phenyl ketone benzoylates primary and secondary aliphatic alcoholic groups in compounds also containing a phenolic group in the presence of 2-10 mol % of PMDETA organocatalyst at room temperature in high yields and excellent selectivity. It also shows the potential to selectively benzoylate primary alcoholic groups of aminoarylalkanols and primary-secondary diols as well as primary amino group of alkyl amines in the presence of aryl amines under similar conditions. A rationale for the selectivity and efficiency of the reaction has been provided.
- Ram, Ram N.,Soni, Vineet Kumar,Gupta, Dharmendra Kumar
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p. 9068 - 9075
(2012/11/07)
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- DMAP-organocatalyzed O-silyl-O-(or C-)-benzoyl interconversions by means of benzoyl fluoride
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A mild and efficient transprotection of alcohols from silyl ethers 1a-f to benzoates 2a-f is reported in fair to good yields (50-98%). This silyl-acyl exchange reaction proceeds readily in acetonitrile at room temperature in the presence of benzoyl fluoride and DMAP as an acyl transfer catalyst. A two-step 'one-pot' DMAP-catalyzed silylcyanation-transprotection sequence which gives the corresponding O-benzoyl cyanohydrines 2g-l in high yields (72-98%) from various benzaldehyde and ketone derivatives is also reported. This original organocatalytic acyl transfer process was also found to be effective in the O-benzoylation of trimethysilyl enolates 1m-o, providing enol esters 2m-o. Lastly, the potential of this strategy is also illustrated by a DMAP-mediated Claisen condensation between ketene silyl acetals 1p-r and benzoyl fluoride. Georg Thieme Verlag Stuttgart.
- Poisson, Thomas,Dalla, Vincent,Papamica?l, Cyril,Dupas, Georges,Marsais, Francis,Levacher, Vincent
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p. 381 - 386
(2008/01/08)
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- Efficient access to orthoquinols and their [4 + 2] cyclodimers via SIBX-mediated hydroxylative phenol dearomatization
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(Chemical Equation Presented) SIBX, the nonexplosive formulation of the λ5-iodane 2-iodoxybenzioc acid (IBX), safely and efficiently mediates the hydroxylative dearomatization of various 2-alkylphenols and napthols into orthoquinols or their [4 + 2] cyclodimers. Reactions are typically run at room temperature using SIBX as a suspension in THF. Using these conditions, natural products such as the cyclodimer of the terpene carvacrol and, for the first time, the shikimate-derived (±)-grandifloracin were prepared in one step from their respective phenolic precursor.
- Lebrasseur, Nathalie,Gagnepain, Julien,Ozanne-Beaudenon, Aurelie,Leger, Jean-Michel,Quideau, Stephane
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p. 6280 - 6283
(2008/02/10)
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- PROTECTION DES PHENOLS PAR LE GROUPEMENT AZIDOMETHYLENE APPLICATION A LA SYNTHESE DE PHENOLS INSTABLES
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Phenols are protected by the azidomethylene group in basic, nucleophilic, oxidative, weakly reductive and weakly acidic media.This group is obtained by the reaction of sodium azide with aryloxymethyl chlorides.Its utility lies in the ease with which it can be removed under very mild conditions which allows the synthesis of very unstable phenolic compounds.
- Loubinoux, Bernard,Tabbache, Samir,Gerardin, Philippe,Miazimbakana, Joseph
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p. 6055 - 6064
(2007/10/02)
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- DIALKYL ACYLPHOSPHONATES: A NEW ACYLATING AGENT OF ALCOHOLS
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Diethyl benzoylphosphonate (1) underwent facile benzoylation of alcohols in the presence of DBU.Reactions of diols containing primary and secondary hydroxyl groups with 1 gave predominantly monobenzoates in which primary hydroxyl groups were highly selectively benzoylated.Related acylations were also described.
- Sekine, Mitsuo,Kume, Akiko,Hata, Tsujiaki
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p. 3617 - 3620
(2007/10/02)
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