120053-18-1Relevant articles and documents
Radical Cyclization Followed by the Fragmentation of Carbonyl Compounds: Effect of an α-Benzoyl Group
Chien, Li-An,Chang, Che-Chien
, p. 11294 - 11301 (2015)
To study a recently developed radical cyclization reaction followed by a fragmentation process in more detail, a series of α-benzoyl carbonyl compounds were prepared, including precursors with aldehyde and ketone moieties. Initiated by tributyltin hydride
Synthesis of an Enantiomerically Pure Inherently Chiral Calix[4]Arene Phosphonic Acid and Its Evaluation as an Organocatalyst
Karpus, Andrii,Yesypenko, Oleksandr,Boiko, Vyacheslav,Daran, Jean-Claude,Voitenko, Zoia,Kalchenko, Vitaly,Manoury, Eric
, p. 1146 - 1153 (2018/02/09)
A facile method for the preparation of enantiomerically pure inherently chiral calix[4]arene phosphonic acid (cR,pR)-7 in four steps starting from the readily available and previously synthesized (cS)-enantiomer of calix[4]arene acetic acid 1 or its methyl ester 2 was developed. The first tests of this unique calixarene Br?nsted acid with inherent chirality in organocatalysis of the aza-Diels-Alder reaction of imines with Danishefsky's diene and epoxide ring opening by benzoic acid were performed. The calixarene phosphonic acid (cR,pR)-7 shows good catalytic activities but with low enantioselectivities in these reactions.
The Activation of Carboxylic Acids via Self-Assembly Asymmetric Organocatalysis: A Combined Experimental and Computational Investigation
Monaco, Mattia Riccardo,Fazzi, Daniele,Tsuji, Nobuya,Leutzsch, Markus,Liao, Saihu,Thiel, Walter,List, Benjamin
, p. 14740 - 14749 (2016/11/18)
The heterodimerizing self-assembly between a phosphoric acid catalyst and a carboxylic acid has recently been established as a new activation mode in Br?nsted acid catalysis. In this article, we present a comprehensive mechanistic investigation on this activation principle, which eventually led to its elucidation. Detailed studies are reported, including computational investigations on the supramolecular heterodimer, kinetic studies on the catalytic cycle, and a thorough analysis of transition states by DFT calculations for the rationalization of the catalyst structure-selectivity relationship. On the basis of these investigations, we developed a kinetic resolution of racemic epoxides, which proceeds with high selectivity (up to s = 93), giving the unreacted epoxides and the corresponding protected 1,2-diols in high enantiopurity. Moreover, this approach could be advanced to an unprecedented stereodivergent resolution of racemic α-chiral carboxylic acids, thus providing access to a variety of enantiopure nonsteroidal anti-inflammatory drugs and to α-amino acid derivatives.
