- Efficient method for the preparation of carboxylic acid alkyl esters or alkyl phenyl ethers by a new-type of oxidation-reduction condensation using 2,6-dimethyl-1,4-benzoquinone and alkoxydiphenylphosphines
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A new-type of oxidation-reduction condensation proceeded smoothly to afford carboxylic acid alkyl esters or alkyl phenyl ethers in good to high yields by combined use of alkoxydiphenylphosphines (1) having primary, bulky secondary or tertiary alkoxy groups, a mild quinone-type oxidant such as 2,6-dimethyl-1,4-benzoquinone (DMBQ) and carboxylic acids or phenols. Generally, alkoxydiphenylphosphines were prepared easily from chlorodiphenylphosphine (2) and alcohols in the presence of pyridine, and were isolated by distillation. On the other hand, the phosphines 1 were also prepared in situ from N,N-dimethylaminodiphenylphosphine (3a) and primary or secondary alcohols while primary, bulky secondary or tertiary alkoxydiphenylphosphines were alternatively formed in situ by adding 2 to the "BuLi-treated alcohols in order to perform the above reactions by a one-pot procedure from alcohols and nucleophiles. The reaction of thus formed 1, DMBQ and carboxylic acids or phenols afforded the corresponding alkylated products, including hindered secondary and tertiary alkylated ones, in good to high yields at room temperature. In the case of using chiral secondary alcohols, the corresponding carboxylic acid alkyl esters were obtained as well in high yields with perfect inversion of stereochemistry by SN2 replacement.
- Shintou, Taichi,Kikuchi, Wataru,Mukaiyama, Teruaki
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p. 1645 - 1667
(2007/10/03)
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- Preparation of various carboxylic acid esters from bulky alcohols and carboxylic acids by a new type oxidation-reduction condensation using 2,6-dimethyl-1,4-benzoquinone
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A new-type oxidation-reduction condensation by using 2,6-dimethyl-1,4-benzoquinone (DMBQ), carboxylic acids and in situ formed alkoxydiphenylphosphines (1) including the bulky alkoxy group-substituted ones proceeded smoothly to afford the corresponding carboxylic acid esters in good to high yields. Alkoxydiphenylphosphines were formed in situ by treating either N,N-dimethylaminodiphenylphosphine (Ph2PNMe2) with primary or secondary alcohols or chlorodiphenylphosphine with the lithium salts of primary, secondary and tertiary alcohols.
- Mukaiyama, Teruaki,Kikuchi, Wataru,Shintou, Taichi
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p. 300 - 301
(2007/10/03)
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- DIRECT FORMATION OF FUNCTIONALIZED KETONES VIA THE COUPLING OF FUNCTIONALIZED ORGANOCOPPER REAGENTS WITH ACID CHLORIDES
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Highly reactive copper solutions have been prepared by the lithium naphtalide reduction of copper(I) iodide/triphenyl-phosphine complex.These copper solutions react rapidly with functionalized alkyl halides to give organocopper reagents wich have been effectively trapped with acid chlorides giving functionalized ketones in good yields.Ester, nitrile, chloride, remote epoxide, and, to some degree, ketone groups can be tolerated by this approach.
- Wehmeyer, Richard M.,Rieke, Reuben D
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p. 4513 - 4516
(2007/10/02)
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- Benzoyl Trifluoromethanesulfonate. A Mild Reagent for the Benzoylation of Sterically Hindered Hydroxyls
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Benzoyl trifluoromethanesulfonate (BzOTf) is a highly efficient reagent for the benzoylation of a variety of alcohols under mild conditions.These include hindered secondary and tertiary hydroxyls, phenols, and α-glycols.Sensitive functionality is stable when the reaction is performed in the presence of pyridine.Several unique rearrangements of Lewis acidsensitive compounds were also effected.
- Brown, Lindsey,Koreeda, Masato
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p. 3875 - 3880
(2007/10/02)
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- Benzoyl Trifluoromethanesulphonate. A Highly Efficient Benzoylating Agent for Sterically Hindered Hydroxyl Groups
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Reactions of benzoyl trifluoromethanesulphonate (BzOTf) with a variety of alcohols, including some with sterically hindered secondary and tertiary hydroxy groups, with phenolic compounds, and with 1,2-diols at low temperatures provide the corresponding benzoates in high yield.
- Koreeda, Masado,Brown, Lindsey
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p. 1113 - 1115
(2007/10/02)
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