- Alkyl Halides via Visible Light Mediated Dehalogenation
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Net selective bromination and chlorination of activated C-H bonds can be effected in generally high yield via a simple perhalogenation/dehalogenation sequence. The photochemical reductions require no photocatalyst, relying instead on the formation of an electron donor-acceptor complex of the substrate and reductant, or alternatively autophotocatalysis. Some reactions proceed despite any apparent photon absorption, serving as a cautionary tale for other photochemical reactions involving amines. Mechanistic experiments provide an explanation for this observation.
- Rathnayake, Manjula D.,Weaver, Jimmie D.
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supporting information
p. 9681 - 9687
(2019/11/28)
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- 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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- Ceric ammonium nitrate (CAN) - A useful catalyst for the rapid and high-yield esterification of carboxylic acids and alcohols with special reference to steroid and other multi-functional natural products
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Ceric ammonium nitrate (CAN) acts as a versatile catalyst for the esterification of carboxylic acids and alcohols, including steroids and other multi-functional natural products, in excellent yields under mild and convenient reaction conditions.
- Goswami,Chowdhury
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p. 955 - 957
(2007/10/03)
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- 2-SACCHARINYLMETHYL ARYL CARBOXYLATES USEFUL AS PROTEOLYTIC ENZYME INHIBITORS AND COMPOSITIONS AND METHOD OF USE THEREOF
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A compound having the formula: STR1 wherein Ar, R 4 and R 5 are defined herein have pharmaceutical utility as proteolytic enzyme inhibitors.
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- Carboxylic acids supported on silica: A smooth acylating agent for alcohols
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An alternative procedure for the esterification of alcohols by short-chain carboxylic acids supported on silica is presented.
- Da Graca Nascimento, Maria,Zanotto, Sandra Patricia,Scremin, Marivania,Rezende, Marcos Caroli
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p. 2715 - 2721
(2007/10/03)
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