4542-76-1Relevant academic research and scientific papers
A new class of bifunctional chiral phase transfer catalysts for highly enantioselective asymmetric epoxidation of α,β-unsaturated ketones at ambient temperature
Ashokkumar, Veeramanoharan,Balasaravanan, Rajendiran,Sadhasivam, Velu,Jenofar, Seenisultanmaideen Mehtob,Siva, Ayyanar
, p. 127 - 136 (2015/09/15)
A new type of bis-quaternary ammonium bromide as chiral multifunctional phase transfer catalysts derived from readily available inexpensive cinchona alkaloids has been developed and evaluated for the enantioselective asymmetric epoxidation of various chalcones in the presence of lower concentrations of various oxidants, bases, solvents and ambient temperature conditions. Under optimized reaction conditions, highest chemical yields of up to 98% along with the excellent enantioselectivities of about 99% were obtained by using the cinchona based chiral multifunctional phase transfer catalysts.
Synthesis and structure-activity analysis of new phosphonium salts with potent activity against African trypanosomes
Taladriz, Andrea,Healy, Alan,Flores Pérez, Eddysson J.,Herrero García, Vanessa,Ríos Martínez, Carlos,Alkhaldi, Abdulsalam A. M.,Eze, Anthonius A.,Kaiser, Marcel,De Koning, Harry P.,Chana, Antonio,Dardonville, Christophe
scheme or table, p. 2606 - 2622 (2012/06/01)
A series of 73 bisphosphonium salts and 10 monophosphonium salt derivatives were synthesized and tested in vitro against several wild type and resistant lines of Trypanosoma brucei (T. b. rhodesiense STIB900, T. b. brucei strain 427, TbAT1-KO, and TbB48). More than half of the compounds tested showed a submicromolar EC50 against these parasites. The compounds did not display any cross-resistance to existing diamidine therapies, such as pentamidine. In most cases, the compounds displayed a good selectivity index versus human cell lines. None of the known T. b. brucei drug transporters were required for trypanocidal activity, although some of the bisphosphonium compounds inhibited the low affinity pentamidine transporter. It was found that phosphonium drugs act slowly to clear a trypanosome population but that only a short exposure time is needed for irreversible damage to the cells. A comparative molecular field analysis model (CoMFA) was generated to gain insights into the SAR of this class of compounds, identifying key features for trypanocidal activity.
Donor-acceptor-donor fluorene derivatives for two-photon fluorescence lysosomal imaging
Yao, Sheng,Ahn, Hyo-Yang,Wang, Xuhua,Fu, Jie,Van Stryland, Eric W.,Hagan, David J.,Belfield, Kevin D.
experimental part, p. 3965 - 3974 (2010/08/19)
As part of a strategy to achieve large two-photon absorptivity in fluorene-based probes, a series of donor-acceptor-donor (D-A-D) type derivatives were synthesized and their two-photon absorption (2PA) properties investigated. The synthesis of D-A-D fluorophores was achieved by efficient preparation of key intermediates for the introduction of central electron acceptor groups. To accomplish the synthesis of two of the new derivatives, a high-yield method for a one-step direct dibromomethylation of phenyl sulfide was developed. The linear and nonlinear optical properties, including UV-vis absorption, fluorescence emission, fluorescence anisotropy, and two-photon absorption (2PA), of the new D-A-D compounds were measured and compared to their D-A or D-D counterparts. Fully conjugated acceptor moieties in the center of the D-A-D fluorophore led to the greatest increase in the 2PA cross section, while weakly conjugated central acceptors exhibited only a modest increase in the 2PA cross section relative to D-A diploar analogs. Encapsulation of the new probes in Pluronic F 108NF micelles, and subsequent incubation in HCT 116 cells, resulted in very high lysosomal colocalization (>0.98 colocalization coefficient) relative to commercial Lysotracker Red, making the micelle-encapsulated dyes particularly attractive as fluorescent probes for two-photon fluorescence microscopy lysosomal imaging.
Synthesis and photovoltaic properties of novel solution-processable triphenylamine-based dendrimers with sulfonyldibenzene cores
Li, Kunpeng,Qu, Jiali,Xu, Bin,Zhou, Yinhua,Liu, Leijing,Peng, Ping,Tian, Wenjing
experimental part, p. 2120 - 2127 (2009/12/25)
Three conjugated dendrimers containing electron-accepting sulfonyldibenzene (SDB) cores and electron-donating triphenylamine dendrons have been synthesized through a convergent synthetic strategy without any protection/deprotection chemistry. The dendrimers were highly soluble in common organic solvents, and could form good quality optical films by spin coating. Their thermal, optical and electrical properties are manipulated by attaching different peripheral dendrons. Using these dendrimers as donors and [6,6]-phenyl C61-butyric acid methyl ester (PCBM) as acceptor, the bulk heterojunction solar cells with a structure of ITO-PEDOT-dendrimers:PCBM-LiF-Al were fabricated. The cell based on dendrimer G0 shows a relatively high power-conversion efficiency (PCE) of 0.34% under AM 1.5 illumination of 100 mW cm-2.
Synthesis of cyclic polymers: Ring-expansion reaction of cyclic s-dithioester with thiiranes
Kudo, Hiroto,Makino, Shinya,Kameyama, Atsushi,Nishikubo, Tadatomi
, p. 5964 - 5969 (2008/02/01)
The ring-expansion reaction of equimolar cyclic dithioester 1 with 3-phenoxypropyrene sulfide (PPS) (cyclic dithioester 1/PPS = 1/2) was examined in the presence of TBAC as a catalyst in NMP for 24 h, It was found that intermodular ester-exchange reaction
Strong binding of alkylguanidinium ions by molecular tweezers: An artificial selective arginine receptor molecule with a biomimetic recognition pattern
Schrader, Thomas
, p. 1537 - 1541 (2007/10/03)
Bisphosphonates 2 and 3 represent the first artificial receptor molecules for alkylguanidinium ions. They bind to the guanidinium moiety by forming a 1:l chelate complex, stabilized by a planar network of electrostatic interactions and hydrogen bonds. Thi
