Convenient Formation of Diphenylmethyl Esters Using Diphenylmethyl Trichloroacetimidate
摘要:
Diphenylmethyl trichloroacetimidate is a useful reagent for the protection of carboxylic acids as their corresponding diphenylmethyl esters. These esterifications proceed rapidly without the need for an added catalyst or promoter. A variety of carboxylic acid substrates undergo esterification in excellent yields with the trichloroacetimidate reagent, including substrates possessing acid- or base-sensitive functionality. Protection of a carboxylic acid with a highly enolizable alpha-stereocenter using diphenylmethyl imidate was also accomplished without racemization.
Ester Formation via Symbiotic Activation Utilizing Trichloroacetimidate Electrophiles
作者:Nivedita S. Mahajani、Rowan I. L. Meador、Tomas J. Smith、Sarah E. Canarelli、Arijit A. Adhikari、Jigisha P. Shah、Christopher M. Russo、Daniel R. Wallach、Kyle T. Howard、Alexandra M. Millimaci、John D. Chisholm
DOI:10.1021/acs.joc.9b00745
日期:2019.6.21
Trichloroacetimidates are useful reagents for the synthesis of esters under mild conditions that do not require an exogenous promoter. These conditions avoid the undesired decomposition of substrates with sensitive functional groups that are often observed with the use of strong Lewis or Brønsted acids. With heating, these reactions have been extended to benzyl esters without electron-donating groups. These inexpensive
Asymmetric Conjugate Additions of Chiral Phosphonamide Anions to α,β-Unsaturated Carbonyl Compounds. A Versatile Method for Vicinally Substituted Chirons
作者:Stephen Hanessian、Arthur Gomtsyan、Nadia Malek
DOI:10.1021/jo000388g
日期:2000.9.1
Reactions of anions derived from chiral nonracemic allyl, crotyl, and cinnamyl bicyclic C(2)-symmetrical phosphonamides with alpha, beta-unsaturated cyclic ketones, esters, lactones, and lactams take place at the gamma-position of the reagents. The products are diastereomerically pure or enriched beta-substituted carbonylcompounds. The method also provides easy access to vicinal substitution of as
Synthesis of Esters by in Situ Formation and Trapping of Diazoalkanes
作者:Richard A. Squitieri、Galen P. Shearn-Nance、Jason E. Hein、Jared T. Shaw
DOI:10.1021/acs.joc.6b00408
日期:2016.7.1
method has been developed for the in situ formation and trapping of diazoalkanes by carboxylic acids to form esters. The method is applicable to a large variety of carboxylic acids using diazo compounds that are formed from the hydrazones of benzaldehydes and aryl ketones. In situ reaction monitoring with IR spectroscopy (ReactIR) was used to demonstrate that slow addition of the hydrazone to a mixture
Synthesis of (E)-cinnamyl ester derivatives via a greener Steglich esterification
作者:Andrew B. Lutjen、Mackenzie A. Quirk、Allycia M. Barbera、Erin M. Kolonko
DOI:10.1016/j.bmc.2018.04.007
日期:2018.10
Cinnamic acid derivatives are known antifungal, antimicrobial, antioxidant, and anticancer compounds. We have developed a facile and mild methodology for the synthesis of (E)-cinnamate derivatives using a modified Steglich esterification of (E)-cinnamic acid. Using acetonitrile as the solvent, rather than the typical chlorinated solvent, and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) as the
Herstellung und Hydrogenolyse von Benzhydrylestern
作者:E. Hardegger、Z. El Heweihi、F. G. Robinet
DOI:10.1002/hlca.19480310220
日期:——
Die Herstellungvon Benzhydrylestern aus Carbonsäuren und Diphenyldiazomethan wurde rnit der Absicht durchgeführt, den für den Ablauf chemischer Reaktionen oft störenden Einfluss freier Carboxylgruppen vorübergehend auszuschalten. Aus den Benzhydrylestern lassen sich, von wenigen Ausnahmen abgesehen, die ursprünglichen Säuren durch Hydrogenolyse rnit Wasserstoff in Gegenwart von Palladium-Kohle regenerieren