83822-64-4Relevant academic research and scientific papers
Highly Acidic Conjugate-Base-Stabilized Carboxylic Acids Catalyze Enantioselective oxa-Pictet–Spengler Reactions with Ketals
Zhu, Zhengbo,Odagi, Minami,Zhao, Chenfei,Abboud, Khalil A.,Kirm, Helmi Ulrika,Saame, Jaan,L?kov, M?rt,Leito, Ivo,Seidel, Daniel
supporting information, p. 2028 - 2032 (2019/12/24)
Acyclic ketone-derived oxocarbenium ions are involved as intermediates in numerous reactions that provide valuable products, however, they have thus far eluded efforts aimed at asymmetric catalysis. We report that a readily accessible chiral carboxylic acid catalyst exerts control over asymmetric cyclizations of acyclic ketone-derived trisubstituted oxocarbenium ions, thereby providing access to highly enantioenriched dihydropyran products containing a tetrasubstituted stereogenic center. The high acidity of the carboxylic acid catalyst, which exceeds that of the well-known chiral phosphoric acid catalyst TRIP, is largely derived from stabilization of the carboxylate conjugate base through intramolecular anion-binding to a thiourea site.
High-pressure-promoted uncatalyzed ketalization of ketones and oxy-Michael/ketalization of conjugated enones
Kumamoto, Koji,Ichikawa, Yoshiyasu,Kotsuki, Hiyoshizo
, p. 2254 - 2256 (2007/10/03)
A new practical method for ketalization or oxy-Michael/ketalization was developed using the high-pressure-promoted condensation of ketones or α,β-unsaturated ketones with alcohols in the presence of trialkyl orthoformates as water scavengers. Georg Thieme Verlag Stuttgart.
