60045-27-4Relevant articles and documents
Expeditious synthesis of carboxylic esters and high-yielding macrolactones using trifluoromethyl-substituted benzoic anhydrides with 4-(dimethylamino)pyridine: An evaluation of the reactivities of aromatic acid anhydrides as dehydration reagents compared with 2-methyl-6-nitrobenzoic anhydride
Shiina, Isamu,Tonoi, Takayuki
, p. 255 - 275 (2017)
Trifluoromethyl-substituted benzoic anhydrides as structural congeners of 2-methyl-6-nitrobenzoic anhydride (MNBA) were prepared and investigated for comparative reactivity in the synthesis of carboxylic esters and macrolactones. 2-Fluoro-6-(trifluoromethyl)benzoic anhydride (FTFBA) was found to be a promising dehydrating agent in the presence of 4-(dimethylamino)pyridine (DMAP), and was successfully employed in the synthesis of threo-aleuritic acid lactone in good yield with high chemoselectivity.
Selective Reduction of Carboxylic Acids to Alcohols in the Presence of Alcohols by a Dual Bulky Transition-Metal Complex/Lewis Acid Catalyst
Gr?mer, Bendik,Saito, Susumu,Yoshioka, Shota
, p. 1957 - 1964 (2022/02/10)
Here, we report a molecular method for the generally applicable reduction of mono-and dicarboxylic acids that selectively furnishes a diverse variety of alcohols, including mono-and diols. One of the inherent drawbacks of the direct hydrogenation of carboxylic acids to alcohols is the in situ formation of the corresponding esters via condensation of the carboxylic acids with the produced alcohols. Especially, the hydrogenation of polycarboxylic acids frequently suffers from the formation of a complex mixture of oligomeric esters. This issue was successfully overcome by the combined use of a dual catalyst that consists of a bulky (PNNP)iridium complex and a Lewis acid. Owing to the steric bulk and robustness of the iridium catalyst, the main role of the Lewis acid is to independently catalyze the esterification, albeit the cooperative activation of (a resting state of) the iridium catalyst by the Lewis acid also seems to be implied.
Development of effective bidentate diphosphine ligands of ruthenium catalysts toward practical hydrogenation of carboxylic acids
Saito, Susumu,Wen, Ke,Yoshioka, Shota
supporting information, p. 1510 - 1524 (2021/06/18)
Hydrogenation of carboxylic acids (CAs) to alcohols represents one of the most ideal reduction methods for utilizing abundant CAs as alternative carbon and energy sources. However, systematic studies on the effects of metal-to-ligand relationships on the catalytic activity of metal complex catalysts are scarce. We previously demonstrated a rational methodology for CA hydrogenation, in which CA-derived cationic metal carboxylate [(PP)M(OCOR)]+ (M = Ru and Re; P = one P coordination) served as the catalyst prototype for CA self-induced CA hydrogenation. Herein, we report systematic trial- and-error studies on how we could achieve higher catalytic activity by modifying the structure of bidentate diphosphine (PP) ligands of molecular Ru catalysts. Carbon chains connecting two P atoms as well as Ar groups substituted on the P atoms of PP ligands were intensively varied, and the induction of active Ru catalysts from precatalyst Ru(acac)3 was surveyed extensively. As a result, the activity and durability of the (PP)Ru catalyst substantially increased compared to those of other molecular Ru catalyst systems, including our original Ru catalysts. The results validate our approach for improving the catalyst performance, which would benefit further advancement of CA self-induced CA hydrogenation.
