828933-86-4Relevant articles and documents
Asymmetric Hydroesterification of Diarylmethyl Carbinols
Tian, Duanshuai,Xu, Ronghua,Zhu, Jinbin,Huang, Jianxun,Dong, Wei,Claverie, Jerome,Tang, Wenjun
, p. 6305 - 6309 (2021/02/09)
An efficient asymmetric hydroesterfication of diarylmethyl carbinols is developed for the first time with a Pd-WingPhos catalyst, resulting in a series of chiral 4-aryl-3,4-dihydrocoumarins in excellent enantioselectivities and good yields. The method features mild reaction conditions, a broad substrate scope, use of easily accessible starting materials, and low palladium loadings. A plausible stereochemical model is also proposed with the Pd-WingPhos catalyst. This method has enabled a 4-step asymmetric synthesis of (R)-tolterodine from readily available starting materials.
Computationally-Led Ligand Modification using Interplay between Theory and Experiments: Highly Active Chiral Rhodium Catalyst Controlled by Electronic Effects and CH–π Interactions
Korenaga, Toshinobu,Sasaki, Ryo,Takemoto, Toshihide,Yasuda, Toshihisa,Watanabe, Masahito
, p. 322 - 333 (2018/01/22)
A chiral ligand for the rhodium-catalyzed asymmetric 1,4-addition of an arylboronic acid to a coumarin substrate that could markedly reduce catalyst loading was developed using interplay between theoretical and experimental approaches. Evaluation of the transition states for insertion and for hydrolysis of intermediate complexes (which were emphasized in response to the experimental results) using DFT calculations at the B97D/6-31G(d) level with the LANL2DZ basis set for rhodium revealed that: (i) the electron-poor nature of the ligands and (ii) CH–π interactions between the ligand and coumarin substrates played significant roles in both acceleration of insertion and inhibition of ArB(OH)2 decomposition (protodeboronation). The computationally-designed ligand, incorporating the above information, enabled a decrease in the catalyst loading to 0.025 mol% (S/C=4,000), which is less than one one-hundredth relative to past catalyst loadings of typically 3 mol%, with almost complete enantioselectivity. Furthermore, the gram-scale synthesis of the urological drug, (R)-tolterodine (l)-tartrate, was demonstrated without the need of intermediate purification. (Figure presented.).
Coumarins from free ortho -hydroxy cinnamates by Heck-Matsuda arylations: A scalable total synthesis of (R)-tolterodine
Barancelli, Daniela A.,Salles, Airton G.,Taylor, Jason G.,Correia, Carlos Roque D.
, p. 6036 - 6039 (2013/02/23)
Free ortho-hydroxy cinnamate ester derivatives are evaluated in the synthesis of structurally diverse 4-aryl-coumarins via a tandem Heck-Matsuda cyclization reaction. Free phenolic groups were considered incompatible with such a reaction, which usually provide the corresponding diazo dyes. A concise and scalable route employing a ligand-free, Pd-catalyzed Heck-Matsuda arylation under aerobic conditions for the preparation of (R)-Tolterodine in high overall yield and ee is also presented.