78308-00-6Relevant academic research and scientific papers
Use of Highly Cross-Linked Polystyrene Supports for Acylation and Alkylation of an Ester Enolate at Room Temperature
Chang, Young H.,Ford, Warren T.
, p. 5364 - 5371 (1981)
The enolate of polystyrene-bound 3-phenylpropanoic ester is prepared with (triphenylmethyl)lithium in tetrahydrofuran at room temperature and is trapped with carboxylic acid chlorides and alkyl bromides.Gas chromatographic yields exceed 90percent, and isolated yields are 73-87percent with a partially esterified 10percent divinylbenzene-cross-linked gel copolymer containing 0.67 mmol of ester/g of copolymer.Yields of p-nitrobenzoylation and self-condensation depend upon the degree of cross-linking of the polystyrene support, the gel or macroporous morphology of the polymer, the degree of functionalization of the polymer, the percent conversion of the chloromethyl polystyrene to ester, the structure of the base used to form the enolate, the time between enolate generation and trapping with p-nitrobenzoyl chloride, and the temperature.Yields of acylation product increase, and self-condensation of the ester decreases as percent cross-linking increases from 2percent to 20percent and as the concentration of ester in fully esterified polymers decreases from 1.08 to 0.18 mmol/g of polymer.When the original esterification of the polymer is carried to only partial conversion, the subsequent enolate acylation yields increase, conversion, the subsequent enolate acylation yields increase, self-condensation yields decrease, and unreacted ester yields decrease.Macroporous 20percent cross-linked polymers gave better site isolation than 10percent cross-linked gel polymers but lacked the physical stability necessary for recycling.One sample of 10percent cross-linked gel polymer in three esterification/enolate acylation/hydrolysis cycles showed no decrease in acylation yield but a decrease in the degree of functionalization.The higher degrees of cross-linking and functionalization of the polystyrene in this work than in similar experiments with a conventional 2percent cross-linked polystyrene enable ester enolate acylation in 77percent yield at room temperature on a 0.1-mol scale in just 1400 mL of reaction mixture.
Indium-catalyzed coupling reaction between silyl enolates and alkyl chlorides or alkyl ethers
Nishimoto, Yoshihiro,Saito, Takahiro,Yasuda, Makoto,Baba, Akio
experimental part, p. 5462 - 5471 (2009/12/01)
The coupling reactions of alkyl chlorides with silyl enolates catalyzed by InBr3, and the coupling reactions of alkyl ethers with silyl enolates catalyzed by the combined Lewis acid of InBr3/Me3SiBr are described. In both reaction systems, various types of silyl enolates were used to give corresponding α-alkylated esters, ketones, carboxylic acids, amides, thioesters, and aldehydes.
A novel type of structurally simple nonpeptide inhibitors for α- chymotrypsin. Induced-fit binding of methyl 2-allyl-3-benzene-propanoate to the S2 subsite pocket
Kim, Dong H.,Li, Zhi-Hong,Lee, Soo Suk,Park, Jeong-Il,Chung, Sang J.
, p. 239 - 249 (2007/10/03)
Unexpectedly, methyl and benzyl esters of 2-allyl-3-benzenepropanoic acid were found to be not substrates but potent competitive inhibitors for α-chymotrypsin. The inhibitory property of the structurally simple nonpeptidic compounds is ascribed to their high binding affinity to the enzyme at the S2 rather than S1 subsite pocket. These inhibitors exist in a flexible form in solution, but as they bind to the enzyme bulky contrained conformers present in a minute concentration play an important role, forming tighter enzyme-inhibitor complexes by binding to the large hydrophobic S2 pocket. The contrained conformers are thought to be resulted from intramolecular CH/π interactions between a vinylic proton and the aromatic π-electron cloud in the inhibitor molecules. These compounds constitute novel examples of the induced-fit binding inhibitor of possibly simplest structure.
Acylations and Alkylations of an Ester Enolate in High Yield at Room Temperature on Polystyrene Supports
Chang, Young H.,Ford, Warren T.
, p. 3756 - 3758 (2007/10/02)
Polymer-bound esters of 3-phenylpropanoic acid are converted to enolates at room temperature and acylated and alkylated in 73-87percent isolated yields with little or no self-condensation of ester.
