An efficient and general procedure was developed for the direct alkylation of H-phosphinate esters with LiHMDS at low temperature. 1084 CHAPTER 22 • THE CHEMISTRY OF ENOLATE IONS, ENOLS, AND a,b-UNSATURATED CARBONYL COMPOUNDS Provide a curved-arrow mechanism for this reaction, using B3 as a base (which is part of the enzyme) and | BH as its conjugate acid.
There have been numerous reports on alkylation of aromatics using olefins, alcohols, alkyl esters, and alkyl halides. Enolate alkylations usually work with unhindered primary alkyl iodides, and especially well with S n 2 reactive substrates like methyl, allyl, benzyl and propargyl iodides and bromides, chloromethyl ethers and α-halo esters. Carboxylic acid derivatives, such as esters and amides, are valuable intermediates and products in industry and academia. Journal of the American Chemical Society 2000 , 122 … Alkylation. Reaction type : Nucleophilic substitution.
The simplicity of the reaction allows the use of various H-phosphinate esters and takes place with a wide range of electrophiles. Ester names are derived from the parent alcohol and the parent acid, where the latter may be organic or inorganic. Acylation provides imides, closer to esters than amides in terms of acidity, enolate nucleophilicity and cleavage chemistry: O NH O H3C CH3 O N O H3C CH3 CH2CH3 O n-BuLi, THF, –78˚C; PrCOCl, 80-90% Evans, D. A.; Bartroli, J.: Shih, T. L. J. 18-8C Alkylation of Ester Anions The anions of esters such as ethyl 3-oxobutanoate and diethyl propanedioate can be alkylated with alkyl halides. A useful approach to modify amides and esters is α-alkylation by alcohols. However, alkylations of these compounds have proved to be challenging. Alkylation is the process by when an alkyl group is added to a substrate molecule. Enantioselective Total Syntheses of Ptilomycalin A, Crambescidin 657 and Its Methyl Ester (Neofolitispates 2), and Crambescidin 800. This allows alkylgroups to be introduced in the a-positions. The alkylation reactions involve modification due to the addition of alkyl group in place of hydrogen species. N -alkyl amino acids find widespread application as highly valuable, renewable building blocks. We report the first powerful catalytic strategy for the direct N-alkylation of unprotected α-amino acids with alcohols.
1981, 103, 2127-2129. Ethers from esters; from exceptional transformation to synthetic method ... Alkylation of an alkoxy anion with an alkylhalide/sulfonate under basic conditions, known as the Williamson synthesis,11,12 is the most frequently used method for the preparation of ethers. Esters derived from the simplest carboxylic acids are commonly named according to the more traditional, so-called "trivial names" e.g.