Enantioselective synthesis of 2,2-difluoro-3-hydroxycarboxylates by rhodium-catalyzed hydrogenation
摘要:
The highly enantioselective synthesis of 2,2-difluoro-3 -hydroxycarboxylates has been achieved by hydrogenating 2,2-difluoro-3-oxocarboxylates in the presence of chiral rhodium-(amidephosphine-phosphinite) complexes. Ethyl 4,4,4-triffluoroacetoacetate can be successfully transformed into the enantiomerically enriched 4,4,4-trifluoro-3-hydroxybutanoate in the same manner. (C) 2000 Elsevier Science Ltd. All rights reserved.
N-Fluoropyridinium salts provide a new system of fluorinatingagents by which a wide range of nucleophilic substrates differing in reactivity can be fluorinated due to the varying degree of fluorinating power and also fluorinated very selectively through structural alteration. The scope of selective fluorination should be broadened considerably on the basis of the present results. The N-fluoropyridinium
Apparent Electrophilic Fluorination of 1,3-Dicarbonyl Compounds Using Nucleophilic Fluoride Mediated by PhI(OAc)<sub>2</sub>
作者:Toby J. Nash、Graham Pattison
DOI:10.1002/ejoc.201500370
日期:2015.6
The apparent electrophilicfluorination of 1,3-dicarbonylcompounds using Et3N·3HF as a nucleophilic fluoride source is reported. This reaction requires PhI(OAc)2 as oxidant and can be conducted safely in standard laboratory glassware. Alternative selectivity compared to Selectfluor was observed in some cases. This approach may reduce our reliance on difficult-to-handle fluorine gas and expensive electrophilic
GLYCOSAMINOGLYCAN DERIVATIVE AND METHOD FOR PRODUCING SAME
申请人:SEIKAGAKU CORPORATION
公开号:US20160151506A1
公开(公告)日:2016-06-02
The present invention provides a glycosaminoglycan derivative in which a group derived from glycosaminoglycan and a group derived from a physiologically active substance having at least one of a carboxy group and a hydroxy group are coupled by covalent bond with a spacer therebetween, in which the spacer is selected in accordance with the decomposition rate of the covalent bond to the group derived from the physiologically active substance.
Microwave-assisted rapid electrophilic fluorination of 1,3-dicarbonyl derivatives with Selectfluor®
作者:Ji-Chang Xiao、Jean’ne M. Shreeve
DOI:10.1016/j.jfluchem.2004.10.043
日期:2005.4
A microwave-assisted fluorination method for 1,3-dicarbonyl compounds using Selectfluor® has been developed. 2-Monofluorinated products can be obtained in high yield in neutral reaction conditions with addition of 1 eq. of Selectfluor®. Treatment of 1,3-dicarbonyls with 3 eq. of Selectfluor® in the presence of tetrabutylammonium hydroxide (TBAH) as the base results in the formation of 2,2-difluorinated
Towards Greener Fluorine Organic Chemistry: Direct Electrophilic Fluorination of Carbonyl Compounds in Water and Under Solvent-Free Reaction Conditions
作者:Gaj Stavber、Stojan Stavber
DOI:10.1002/adsc.201000477
日期:2010.11.2
Selective and efficient fluorination of organic 1,3-dicarbonyl compounds was achieved using the electrophilic fluorinating reagents SelectfluorTMF-TEDA-BF4 (1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis-tetrafluoroborate) in aqueous medium or AccufluorTMNFSi (N-fluorobenzenesulfonimide) under solvent-free reaction conditions (SFRC). Under both reaction conditions cyclic 1,3-dicarbonyl