The alkylation of the enolates of methyl bis-(pentamethylphenyl)acetate and of isopropyl bis(pentachlorophenyl)acetate occurs exclusively on oxygen to yield the diarylketene acetals; the extreme steric hindrance of these groups is also responsible for the stability of these ketene acetals in acid....
To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option.doi:10.1002/chin.199320147S. GHOSHDep. Org. Chem., Solid State Phys., Indian Ass. Cultiv. Sci., Jadavpur, Calcutta...
The diastereoselectivities of the alkylated products were similar to those observed in the deprotonation steps. The stereochemical outcome can be interpreted by an intramolecular complexation of the lithium cation of the carbohydrate ester enolates.doi:10.1080/07328309608005685...
Parameters obtained from the analysis of proton magnetic resonance spectra of several alkylethylenes are reported. From these values and others previously reported, it may be deduced that: (1) the spin-spin coupling constant between prot... AA Bothner-By,C Naar-Colin - 《Journal of the America...
A second substrate- directed alkylation with bromomethyl hydantoin 4 was carried out at the t-butyl ester enolate position to afford intermediate 5. There is a pronounced cation effect on the diastereoselectivity. For example, use of LDA resulted in a 15:85 ratio of anti-5:syn-5 diastereomers...
19. Reactions of Aromatics: EAS and Beyond5h 1m 20. Phenols55m 21. Aldehydes and Ketones: Nucleophilic Addition4h 56m 22. Carboxylic Acid Derivatives: NAS2h 51m 23. The Chemistry of Thioesters, Phophate Ester and Phosphate Anhydrides1h 10m 24. Enolate Chem...
The stereochemistry of the reaction is interpreted in terms of a conformational shift on deprotonation of the ester.关键词: benzylisobornyl esters alkylations stereoselectivity lithium enolates steric hindrance DOI: 10.1055/s-2002-33115 被引量: 1 ...
Xu Jiayi.Asymmetric allylic alkylation of cyclic vinylogous esters and thioesters by Pd-catalyzed decarboxylation of enol carbonate and-keto ester substrates. ... BM Trost,RN Bream,J Xu - 《Angewandte Chemie》 被引量: 0发表: 2006年 Asymmetric Allylic Alkylation of Cyclic Vinylogous Esters and ...
In principle, this is an attractive strategy in comparison to the traditional alkylation of stoichiometrically formed enolates using alkyl halides: alcohol substrates are commercially abundant and stable, the process is catalytic in a weaker base, and water is generated as the sole by-product (Fig....
Enantioselective palladium-catalyzed decarboxylative allylic alkylations 中科院上海有机化学研究所 SL You,LX Dai - 《Angewandte Chemie》 被引量: 158发表: 2010年 Palladium-catalyzed asymmetric allylic alkylation of 2-acylimidazoles as ester enolate equivalents. A broad range of highly enantioenriched 2-ac...