Decreasing Side Products and Increasing Selectivity in the Tandem Hydroformylation/Acyloin Reaction
作者:Karoline A. Ostrowski、Thiemo A. Faßbach、Dennis Vogelsang、Andreas J. Vorholt
DOI:10.1002/cctc.201500727
日期:2015.9.1
to a variety of olefins is enabled with comparable excellent selectivities up to >99 % for the first and second reaction step, therefore a general synthesis for the conversion of olefins into acyloins is found. Furthermore, very good to excellent yields for the intermediates and final acyloin products were observed within two catalysed reactions in one preparative step. The acyloin product was applied
V-65 as radicalinitiator, the reaction of aldehydes with allyl bromides gave β,γ-unsaturated ketones in good yields (13 examples, 45–84%). The reaction is triggered by hydrogen abstraction from the aldehyde by bromine radical to form an acyl radical, which undergoes an SH2′-type addition–elimination reaction with allyl bromides to give coupling products with liberation of bromine radical. Three-component
Pentamethylcyclopentadienide in organic synthesis: nucleophilic addition of lithium pentamethylcyclopentadienide to carbonyl compounds and carbon–carbon bond cleavage of the adducts yielding the parent carbonyl compounds
dienide (C5Me5Li, Cp*Li) reacted with aromatic aldehyde to provide the corresponding carbinol in excellent yield. The carbinol returns to the parent aldehyde and pentamethylcyclopentadiene upon exposure to acid or due to heating. Chlorodimethylaluminum is essential as an additive to attain the nucleophilic addition of Cp*Li to aliphatic aldehyde. The carbinol derived from aliphatic aldehyde returns
五甲基环戊二烯化锂(C 5 Me 5 Li,Cp * Li)与芳族醛反应以优异的产率提供相应的甲醇。甲醇在暴露于酸中或加热后会返回为母体醛和五甲基环戊二烯。氯二甲基铝对于实现Cp * Li向脂肪族醛的亲核加成反应至关重要。衍生自脂族醛的甲醇在催化量的2,3-二氯-5,6-二氰基苯并醌(DDQ)的作用下返回母体醛和五甲基环戊二烯。Cp *基团的可逆加成/消除可表示对醛的保护。还公开了碳-碳键裂解的机理细节。
Straightforward Synthesis of Fluorinated Enals <i>via</i> Photocatalytic α-Perfluoroalkenylation of Aldehydes
作者:Christian Wulkesch、Constantin Czekelius
DOI:10.1021/acs.joc.1c00383
日期:2021.6.4
(Per)fluorinated substances represent an important compound class with regard to drug design and material chemistry. We found a mild, operationally simple, and inexpensive photocatalytic perfluoroalkenylation reaction giving tetrasubstituted, highly electron-deficient enals straight from aldehydes. This one-step reaction tolerates various functional groups and can be applied to a wide range of substrates
Cerium(III) Chloride-Mediated Reactions of Sulfonamide Dianions
作者:David C. Johnson、Theodore S. Widlanski
DOI:10.1021/jo034001w
日期:2003.6.1
5'-aldehyde, 3'-ketouridine, and 3'-ketothymidine. The reaction was chemoselective for aldehydes in the presence of nitriles. Acetoxy groups are labile and thus not suitable protecting groups for alcohols under these conditions. N-Benzyl-alpha, N-dilithio methanesulfonamide was found to be of sufficient basicity to cause enolate formation with sensitive substrates, such as 1-phenylacetone. However, the