13148-18-0Relevant articles and documents
Asymmetric epoxidation of a geminally-disubstituted and some trisubstituted enones catalysed by poly-L-leucine
Bentley, Paul A.,Bickley, Jamie F.,Roberts, Stanley M.,Steiner, Alexander
, p. 3741 - 3743 (2001)
Epoxidation of a range of enones derived from tetralone or related cyclic ketones, employing poly-L-leucine, urea-H2O2 and DBU in iso-propyl acetate is reported. The corresponding epoxides were isolated in 63-85% yield and 59-96% ee.
A porphyrin-inspired iron catalyst for asymmetric epoxidation of electron-deficient olefins
Dai, Wen,Li, Guosong,Chen, Bo,Wang, Lianyue,Gao, Shuang
, p. 904 - 907 (2015)
An in situ formed porphyrin-inspired iron complex that catalyzes asymmetric epoxidation of di- and trisubstituted enones is described. The reaction provides highly enantioenriched α,β-epoxyketones (up to 99% ee). The practical utility of the new catalyst
Asymmetric Epoxidation of Olefins Catalyzed by Substituted Aminobenzimidazole Manganese Complexes Derived from L-Proline
Tian, Jing,Lin, Jin,Zhang, Jisheng,Xia, Chungu,Sun, Wei
supporting information, p. 593 - 600 (2021/11/16)
A family of manganese complexes [Mn(Rpeb)(OTf)2] (peb=1-(1-ethyl-1H-benzo[d]imidazol-2-yl)-N-((1-((1-ethyl-1H-benzo[d]imidazol-2-yl)methyl) pyrrolidin-2-yl)methyl)-N-methylmethanamine)) derived from L-proline has been synthesized and characterized, where R refers to the group at the diamine backbone. X-ray crystallographic analyses indicate that all the manganese complexes [Mn(Rpeb)(OTf)2] exhibit cis-α topology. These types of complexes are shown to catalyze the asymmetric epoxidation of olefins employing H2O2 as a terminal oxidant with up to 96% ee. Obviously, the R group of the diamine backbone can influence the catalytic activity and enantioselectivity in the asymmetric epoxidation of olefins. In particular, Mn(i-Prpeb)(OTf)2 bearing an isopropyl arm, cannot catalyze the epoxidation reaction with H2O2 as the oxidant. However, when PhI(OAc)2 is used as the oxidant instead, all the manganese complexes including Mn(i-Prpeb)(OTf)2 can promote the epoxidation reactions efficiently. Taken together, these results indicate that isopropyl substitution on the Rpeb ligand inhibits the formation of active Mn(V)-oxo species in the H2O2/carboxylic acid system via an acid-assisted pathway.
Br?nsted Base-Catalyzed Transformation of α,β-Epoxyketones Utilizing [1,2]-Phospha-Brook Rearrangement for the Synthesis of Allylic Alcohols Having a Tetrasubstituted Alkene Moiety
Kondoh, Azusa,Tasato, Naoko,Aoki, Takuma,Terada, Masahiro
supporting information, p. 5170 - 5175 (2020/07/04)
A stereoselective transformation of α,β-epoxyketones into alkenylphosphates having a hydroxymethyl group on the β-carbon was established by utilizing the [1,2]-phospha-Brook rearrangement under Br?nsted base catalysis. The reaction involves the catalytic generation of an α-oxygenated carbanion located at the α-position of an epoxide moiety through the [1,2]-phospha-Brook rearrangement and the following epoxide opening. Further transformation of the alkenylphosphates by the palladium-catalyzed cross-coupling reaction with Grignard reagents provided allylic alcohols having a stereodefined all-carbon tetrasubstituted alkene moiety.
Synthesis of xylal- and arabinal-based crown ethers and their application as asymmetric phase transfer catalysts
Nemcsok, Tamás,Rapi, Zsolt,Bagi, Péter,Keglevich, Gy?rgy,Bakó, Péter
, p. 107 - 119 (2019/11/16)
New xylal- and arabinal-based monoaza-15-crown-5 ethers were synthesized starting from l- and d-xylose, and l- and d-arabinose, respectively. These monosaccharide-based chiral macrocycles were tested as phase transfer catalysts in a few asymmetric reactions. The xylal-based crown compounds proved to be efficient catalysts in a few liquid-liquid phase reactions. The epoxidation of trans-chalcone and the Darzens condensation of α-chloroacetophenone with benzaldehyde took place with complete diastereoselectivity and up to 77% ee and 58% ee, respectively. It was found that the substituents in the aromatic ring of the chalcone and the α-chloroacetophenone had an influence on the enantioselectivity. The highest ee values were obtained in the epoxidation of 4-chlorochalcone (81% ee) and in the reaction of a 2-naphthyl analogue (96% ee), while in the Darzens condensation of 4-phenyl-α-chloroacetophenone with benzaldehyde, a maximum ee of 91% was detected. The configuration of the monosaccharide unit in the crown ring influenced the absolute configuration of the epoxyketones synthesized.
