A facile and efficient protocol for esterification and acetalization in a PEG1000-D(A)IL/toluene thermoregulated catalyst–media combined systems
摘要:
A novel efficient and recyclable temperature-dependent biphasic catalyst and reaction media combined system comprised of PEG-1000 linked dicationic acidic ionic liquid and toluene was developed and applied in esterification of aromatic acids and acetalization of aromatic aldehydes with good to excellent yields. This system is characteristic of temperature-dependent reversible biphasic property, simple and facile recyclability, high catalytic activity and extensive substrate and reaction adaptability. (C) 2013 Elsevier B.V. All rights reserved.
The nickel-catalyzed reductive coupling of alkynes and imines with Et(2)Zn as a reductant by using electron-rich phosphine ligands has been developed, affording various allylic amines with high yields and excellent chemoselectivities. Chiralinduction was also achieved in this reductive coupling reaction when a nickel catalyst containing a chiral spiro phosphine ligand was used.
Process for preparing 3,5:4,6- protected derivatives of L- or D- gulonic acid, their use in preparing 2- keto-L- or D- gulonic acid or their esters or L- or D- ascorbic acid, and certain novel 2-nitrato-gulonate intermediates
申请人:PFIZER INC.
公开号:EP0000243A1
公开(公告)日:1979-01-10
The invention relates to a process in which a 3,5:4,6-protected derivative of L- or D-glulonic acid is prepared by contacting L- or D-gulono-1,4-lactone with an aldehvde dialkyl acetal, or with an aldehyde and an alcohol, in the presence of an acid having a pKa of less than 3. This protected derivative may be oxidised and hydrolysed to 2-keto-L- or D-gulonic acid or ester thereof, which in turn may be hydrolysed to L- or D-ascorbic acid. L-ascorbic acid is of course Vitamin C. The invention also relates to the novel intermediates produced by the above processes.