نتایج جستجو برای: wittig reaction
تعداد نتایج: 412686 فیلتر نتایج به سال:
Control of chemoselectivity is one of the most challenging problems facing chemists and is particularly important in the synthesis of bioactive compounds and medications. Herein, the first highly chemoselective tandem C(sp3)-H arylation/[1,2]-Wittig rearrangement of pyridylmethyl ethers is presented. The efficient and operationally simple protocols enable generation of either arylation products...
The imine intermediate generated by the addition of primary amine to the cinnamaldehyde is trapped by the N-isocyaniminotriphenylphosphorane (Ph3PNNC) and a carboxylic acid, and leads to the formation of the corresponding iminophosphorane intermediate. The 1,3,4-oxadiazole derivatives are formed via intramolecular aza-Wittig reaction of the iminophosphorane intermediate. The reactions were comp...
A method for the synthesis of long chain diamines and tetramines starting from natural α-amino acids is reported. Diamines and tetramines were prepared through the Wittig olefination reaction of N-protected amino aldehydes obtained from phenylalanine and lysine. A 1,2,17,18-tetramine was synthesized using (2S)-1-azido-2-[bis(tertbutoxycarbonyl)-amino]-5-oxopentane as key-intermediate compound.
A facile carbohydrate-based highly stereoselective synthetic route has been developed for the cytospolide P (1) from D-ribose for the first time. Key steps of the synthesis include Wittig homologation, regioselective epoxide ring opening, Sharpless asymmetric epoxidation, Evans aldol reaction, and Yamaguchi macrolactonization.
Since its discovery the rearrangement of R-metalated ethers, particularly the [2,3]-Wittig rearrangement, has been the subject of intensive mechanistic and synthetic investigations.1 Relative to the [2,3]-shift, the [1,2]-Wittig rearrangement has received relatively little publicity. Most studies of the [1,2]-Wittig have been mechanistic in origin, resulting in the widely accepted theory that t...
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