34233-75-5Relevant articles and documents
Catalytic asymmetric difunctionalization of stable tertiary enamides with salicylaldehydes: Highly efficient, enantioselective, and diastereoselective synthesis of diverse 4-chromanol derivatives
He, Ling,Zhao, Liang,Wang, De-Xian,Wang, Mei-Xiang
, p. 5972 - 5975 (2014)
Catalyzed by a chiral BINOL-Ti(OiPr)4 complex, various stable tertiary enamides reacted with salicylaldehydes to afford diverse cis,trans-configured 4-chromanols that contain three continuous stereogenic centers in good yields with excellent diastereoselectivity and enantioselectivity. The reaction proceeded through the addition of enamide to aldehyde followed by the intramolecular interception of the resulting iminium by the hydroxy group. Oxidation of the resulting 4-chromanols yielded almost quantitatively chroman-4-one derivatives which underwent diastereospecific reduction with NaBH4 to produce cis,cis-configured 4-chromanols.
Monoacylation of Symmetrical Diamines in Charge Microdroplets
Ansu-Gyeabourh, Emelia,Amoah, Enoch,Ganesa, Chandrashekar,Badu-Tawiah, Abraham K.
, p. 531 - 536 (2021/01/13)
Monoacylation of symmetrical diamine is achieved when the primary α,ω-diamines (carbon numbers n = 3, 5 and 12) are diluted in ethyl acetate, and the resultant mixture is electrosprayed across a 10 mm distance in ambient air toward a mass spectrometer. The N-acylated product is formed in charged microdroplets without acidifying and activating agents and in the absence of heat. This result provided an insight into the orientation of the amines in the droplets, suggesting that the ester is activated to react with the amine at the droplet surface due to the high abundance of protons at the air-droplet interface.
Axially Chiral Enamides: Substituent Effects, Rotation Barriers, and Implications for their Cyclization Reactions
Clark, Andrew J.,Curran, Dennis P.,Fox, David J.,Ghelfi, Franco,Guy, Collette S.,Hay, Benjamin,James, Natalie,Phillips, Jessica M.,Roncaglia, Fabrizio,Sellars, Philip B.,Wilson, Paul,Zhang, Hanmo
, p. 5547 - 5565 (2016/07/14)
The barrier to rotation around the N-alkenyl bond of 38 N-alkenyl-N-alkylacetamide derivatives was measured (ΔG∞ rotation varied between -1). The most important factor in controlling the rate of rotation was the level of alkene substitution, followed by the size of the nitrogen substituent and, finally, the size of the acyl substituent. Tertiary enamides with four alkenyl substituents exhibited half-lives for rotation between 5.5 days and 99 years at 298 K, sufficient to isolate enantiomerically enriched atropisomers. The radical cyclizations of a subset of N-alkenyl-N-benzyl-α-haloacetamides exhibiting relatively high barriers to rotation round the N-alkenyl bond (ΔG∞ rotation >20 kcal mol-1) were studied to determine the regiochemistry of cyclization. Those with high barriers (>27 kcal mol-1) did not lead to cyclization, but those with lower values produced highly functionalized γ-lactams via a 5-endo-trig radical-polar crossover process that was terminated by reduction, an unusual cyclopropanation sequence, or trapping with H2O, depending upon the reaction conditions. Because elevated temperatures were necessary for cyclization, this precluded study of the asymmetric transfer in the reaction of individual atropisomers. However, enantiomerically enriched atropsiomeric enamides should be regarded as potential asymmetric building blocks for reactions that can be accomplished at room temperature.
