Alpha,beta-unsaturated esters and acids by stereoselective dehydration
申请人:Deng Xiaohu
公开号:US20060004195A1
公开(公告)日:2006-01-05
There are provided by the present invention certain pyrazole based CCK-1 receptor modulators which have the general formula:
wherein Ar is an aromatic or heteroaromatic group, X is a hydrocarbon linker, Y is a bond or hydrocarbon linker and R
1
, R
2
, R
3
, R
4
and R
5
are certain organic substituents, methods for making the same, and stereoselective dehydration methods for generally making α,β-unsaturated esters, acids and their derivatives.
Compounds of formula (I) described herein are inhibitors of the phosphodiesterase 4 (PDE4) enzyme and muscarinic M3 receptor antagonists and are useful for the prevention and/or treatment of diseases of the respiratory tract characterized by airway obstruction.
Metal‐Free Hydrosilylation of Ketenes with Silicon Electrophiles: Access to Fully Substituted Aldehyde‐Derived Silyl Enol Ethers
作者:Avijit Roy、Martin Oestreich
DOI:10.1002/chem.202100877
日期:2021.6.4
catalysts is reported. The boron Lewis acid tris(pentafluorophenyl)borane accelerates the slow uncatalyzed reaction of ketenes and hydrosilanes, thereby providing a convenient access to the new class of β,β-di- and β-monoaryl-substituted aldehyde-derived silyl enolethers. Yields are moderate to high, and Z configuration is preferred. The corresponding silyl bis-enol ethers are also available when using
Highly Enantioselective Direct Alkylation of Arylacetic Acids with Chiral Lithium Amides as Traceless Auxiliaries
作者:Craig E. Stivala、Armen Zakarian
DOI:10.1021/ja205107x
日期:2011.8.10
A direct, highly enantioselective alkylation of arylacetic acids via enediolates using a readily available chiral lithium amide as a stereodirecting reagent has been developed. This approach circumvents the traditional attachment and removal of chiralauxiliaries used currently for this type of transformation. The protocol is operationally simple, and the chiral reagent is readily recoverable.