237753-20-7Relevant articles and documents
Facile one-pot fabrication of a silica gel-supported chiral phase-transfer catalyst - N-(2-cyanobenzyl)-O(9)-allyl-cinchonidinium salt
Feng, Dandan,Xu, Jinghan,Wan, Jingwei,Xie, Bing,Ma, Xuebing
, p. 2141 - 2148 (2015/04/14)
A novel type of silica gel-supported cinchona alkaloid-based quaternary ammonium salt was prepared by available one-pot synthesis for the first time through the free radical addition of the sulfhydryl group of 3-mercaptopropyltrimethoxysilane to an exocyc
9-Amino-(9-deoxy)cinchona alkaloid-derived new chiral phase-transfer catalysts
Peng, Wenwen,Wan, Jingwei,Xie, Bing,Ma, Xuebing
, p. 8336 - 8345 (2015/01/08)
A new class of 9-amino-(9-deoxy)cinchona alkaloid-derived chiral phase-transfer catalysts bearing amino groups was developed by using known cinchona alkaloids as the starting materials. Due to the transformation of the 9-hydroxyl group into a 9-amino functional group, the catalytic performances were significantly improved in comparison with the corresponding first generation phase-transfer catalysts, and excellent yields (92-99%) and high enantioselectivities (87-96% ee) were achieved in the benchmark asymmetric α-alkylation of glycine Schiff base. Based on the special contribution of the amino group to the high yield and enantioselectivity, the possible catalytic mechanism was conjectured. This journal is
Preparation of chiral amino esters by asymmetric phase-transfer catalyzed alkylations of schiff bases in a ball mill
Nun, Pierrick,Perez, Violaine,Calmes, Monique,Martinez, Jean,Lamaty, Frederic
, p. 3773 - 3779 (2012/04/23)
The asymmetric alkylation of Schiff bases under basic conditions in a ball mill was performed. The starting Schiff bases of glycine were prepared beforehand by milling protected glycine hydrochloride and benzophenone imine, in the absence of solvent. The Schiff base was then reacted with a halogenated derivative in a ball mill in the presence of KOH. By adding a chiral ammonium salt derived from cinchonidine, the reaction proceeded asymmetrically under phase-transfer catalysis conditions, giving excellent yields and enantiomeric excesses up to 75 %. Because an equimolar amount of starting material was used, purification was greatly simplified. Copyright
Highly efficient polymer supported phase-transfer catalysts containing hydrogen bond inducing functional groups
Shi, Qinghua,Lee, Yeon-Ju,Kim, Mi-Jeong,Park, Mi-Kyung,Lee, Kyoungyim,Song, Hongrui,Cheng, Maosheng,Jeong, Byeong-Seon,Park, Hyeung-geun,Jew, Sang-sup
, p. 1380 - 1383 (2008/09/18)
Merrifield resin supported cinchona ammonium salts bearing 2′-fluorobenzene, 2′-cyanobenzene and 2′-N-oxypyridine groups were prepared and applied to the phase-transfer catalytic alkylation of N-(diphenylmethylene)glycine tert-butyl ester for the enantios
Asymmetric phase-transfer catalysis of homo- and heterochiral quaternary ammonium salts: development and application of conformationally flexible chiral phase-transfer catalysts
Ooi, Takashi,Uematsu, Yukitaka,Kameda, Minoru,Maruoka, Keiji
, p. 11425 - 11436 (2007/10/03)
Inspired by the considerable difference of catalytic activity and stereocontrolling ability between the conformationally rigid, homo- and heterochiral quaternary ammonium bromides 1, conformationally flexible, N-spiro chiral quaternary ammonium bromides o
Catalytic asymmetric phase-transfer reactions using tartrate-derived asymmetric two-center organocatalysts
Ohshima, Takashi,Shibuguchi, Tomoyuki,Fukuta, Yuhei,Shibasaki, Masakatsu
, p. 7743 - 7754 (2007/10/03)
A new highly versatile asymmetric two-center catalyst, tartrate-derived diammonium salt (TaDiAS), was designed and a catalyst library containing more than 70 new two-center catalysts was constructed. A variety of (S,S)- and (R,R)-TaDiAS were easily synthesized from diethyl L- and D-tartrate, respectively, using common and inexpensive reagents under operationally simple reaction conditions. TaDiAS was used in phase-transfer alkylations and Michael additions to afford various optically active α-amino acid equivalents in up to 93% yield. Moreover, dramatic counter anion effects were observed in phase-transfer catalysis (PTC) for the first time, making it possible to further improve reactivity and selectivity. These findings validate the usefulness of three-dimensional fine-tuning of the catalyst (acetal, Ar, and counter anion) for optimization. Recovery and reuse of the catalyst was also possible using simple procedures. The present asymmetric PTC was successfully applied to enantioselective syntheses of serine protease inhibitor aeruginosin 298-A and its analogues.
Design of N-spiro C2-symmetric chiral quaternary ammonium bromides as novel chiral phase-transfer catalysts: Synthesis and application to practical asymmetric synthesis of α-amino acids
Ooi, Takashi,Kameda, Minoru,Maruoka, Keiji
, p. 5139 - 5151 (2007/10/03)
A series of C2-symmetric chiral quaternary ammonium bromides 10 and 11 have been designed as a new, purely synthetic chiral phase-transfer catalyst, and readily prepared from commercially available optically pure 1,1′-bi-2-naphthol as a basic c
Substituent effect of binaphthyl-modified spiro-type chiral phase-transfer catalysts
Hashimoto, Takuya,Maruoka, Keiji
, p. 3313 - 3316 (2007/10/03)
Binaphthyl-modified spiro-type phase-transfer catalysts possessing 4,4′-diaryl substituents are shown to exhibit high asymmetric induction in asymmetric benzylation of benzophenone imine glycine tert-butyl ester under phase-transfer conditions.
Enantioselective syntheses of aeruginosin 298-A and its analogues using a catalytic asymmetric phase-transfer reaction and epoxidation
Ohshima, Takashi,Gnanadesikan, Vijay,Shibuguchi, Tomoyuki,Fukuta, Yuhei,Nemoto, Tetsuhiro,Shibasaki, Masakatsu
, p. 11206 - 11207 (2007/10/03)
We developed a versatile synthetic process for aeruginosin 298-A as well as several attractive analogues, in which all stereocenters were controlled by a catalytic asymmetric phase-transfer reaction and epoxidation. Furthermore, drastic counteranion effects in phase-transfer catalysis were observed for the first time, making it possible to three-dimensionally fine-tune the catalyst (ketal part, aromatic part, and counteranion). Copyright
Optically active quarternary ammonium salt with axial chirality, method for producing thereof, and application thereof for asymmetric synthesis of α-amino acid
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Example 18, (2010/01/30)
A novel optically active quarternary ammonium salt with an axial chirality is provided. The quarternary ammonium salt can act as a phase-transfer catalyst to convert glycine derivatives into optically active α-amino acid derivatives by stereoselectively a
