Reductive Etherification of Aldehydes and Ketones with Alcohols and Triethylsilane Catalysed by Yb(OTf)
<sub>3</sub>
: an Efficient One‐Pot Benzylation of Alcohols
The one‐pot synthesis of symmetrical and unsymmetrical ethers from aldehydes and ketones can be conveniently performed using Yb(OTf)3 as catalyst and triethylsilane as reducing agent in presence of alcohols. This methodology leads to the synthesis of ether derivatives with good yields. Notably, this process resulted a useful tool to protect alcohols as benzyl ether derivatives using differently substituted
demethylation, debenzylation, and deallylation of aryl ethers using HPPh2 and tBuOK is reported. The reaction features mild and metal-free reaction conditions, broad substrate scope, good functional group compatibility, and high chemical selectivity towards aryl ethers over aliphatic structures. Notably, this approach is competent to selectively deprotect the allyl or benzyl group, making it a general and practical
2-methylpropionic acid derivatives and pharmaceutical compositions comprising the same
申请人:KISSEI PHARMACEUTICAL CO., LTD.
公开号:US20030166719A1
公开(公告)日:2003-09-04
The present invention provides novel 2-methylpropionic acid derivatives represented by the general formula:
1
(wherein R
1
represents a hydroxy group, a lower alkoxy group or an aralkyl group; R
2
represents a hydroxy group, a lower alkyl group or a halogen atom; A represents an oxygen atom or an imino group; the carbon atom marked with (R) represents a carbon atom in R configuration; and the carbon atom marked with (S) represents a carbon atom in S configuration) and pharmaceutically acceptable salts thereof, which have excellent &bgr;
3
-adrenoceptor stimulating effects and are useful as agents for the prevention or treatment of obesity, hyperglycemia, the diseases caused by intestinal hypermotility, pollakiuria, urinary incontinence, depression, or the diseases caused by biliary calculi or hypermotility of biliary tract.
The first and simultaneous total syntheses of cucurbitosides A, B, G, and I, seguinosides C and D, and two unnatural analogs were achieved using the technique of fluorous mixture synthesis. The eight precursors of cucurbitoside-like phenolic glycosides were prepared by glycosylation of a mixture of two glucopyranosyl acceptors bearing different fluorous benzyl groups with a mixture of four apiofuranosyl
2-Methylpropionic acid derivatives and medicinal compositions containing the same
申请人:Kissei Pharmaceutical Co., Ltd.
公开号:US06696489B1
公开(公告)日:2004-02-24
The present invention provides novel 2-methylpropionic acid derivatives represented by the general formula:
(wherein R1 represents a hydrogen atom, a lower alkyl group or an aralkyl group; R2 represents a hydrogen atom a lower alkyl group or a halogen atom; A represents an oxygen atom or an imino group; the carbon atom marked with (R) represents a carbon atom in R configuration; and the carbon atom marked with (S) represents a carbon atom in S configuration) and pharmaceutically acceptable salts thereof, which have excellent &bgr;3-adrenoceptor stimulating effects and are useful as agents for the prevention or treatment of obesity, hyperglycemia, the diseases caused by intestinal hypermotility, pollakiuria, urinary incontinence, depression, or the diseases caused by biliary calculi or hypermotility of the biliary tract.