2844-17-9Relevant articles and documents
Catalytic Amide-Base System of TMAF and N(TMS)3 for Deprotonative Coupling of Benzylic C(sp3)-H Bonds with Carbonyls
Shigeno, Masanori,Nakaji, Kunihito,Nozawa-Kumada, Kanako,Kondo, Yoshinori
supporting information, p. 2588 - 2592 (2019/04/25)
This paper describes that an amide-base generated in situ from tetramethylammonium fluoride (TMAF) and N(TMS)3 catalyzes the deprotonative coupling of benzylic C(sp3)-H bonds with carbonyls to form stilbenes. A variety of methylheteroarenes (2-methylbenzothiophene, 2-methylbenzofuran, and 2-, 3-, or 4-methylpyridines) are used as nucleophiles. Application to enamine synthesis using DMF as an electrophile is also shown. The present system is effective for toluenes (4-phenyl-, 4-bromo-, 2-bromo-, and 4-chlorotoluenes) having low reactivity.
Unconventional Langmuir-Blodgett films: Alignment of an optically nonlinear dye where the donor and π-electron bridge are hydrophobic and the acceptor is hydrophilic
Ashwell, Geoffrey J.,Maxwell, Alison A.,Green, Andrew
, p. 2192 - 2196 (2007/10/03)
The optically nonlinear dye, 5-{4-[2-(4-dibutylaminophenyl)vinyl]benzylidene}-2-(1-ethylpropyl)-5,6,7, 8-tetrahydroisoquinolinium bromide (1a), differs from other Langmuir-Blodgett (LB) film-forming materials. The molecule is amphiphilic and, therefore, may be aligned at the air-water interface but, instead of a conventional aliphatic tail, has an extended π-electron bridge. It forms non-centrosymmetric LB films which exhibit second-harmonic generation (SHG) and have a high second-order susceptibility: χ(2)zzz = 40 pm V-1 at 1.064 μm for a monolayer thickness of 1.8 nm and chromophore tilt angle of 55° from the substrate normal. The octadecyl sulfate salt (1b) also forms non-centrosymmetric films but with improved properties: χ(2)zzz = 90 pm V-1 at 1.064 μm for d = 2.4 nm and φ = 33°. Both films exhibit charge-transfer bands at 360 nm but with absorbance cut-off above 560 nm for 1a and 530 nm for 1b. The latter is fully transparent at the fundamental and harmonic wavelengths and its susceptibility is the highest to date for such a film. This results from an optimised packing arrangement, a conjugation enhanced molecular hyperpolarisability of β = 4.3 × 10-38 m4 V-1, and the proximity of the absorption band, albeit non-overlapping at 532 nm. The properties are compared with those of conventional long alkyl tailed materials (2 and 3) of the same chromophore.
Inhibition of purified and membrane-bound flavin-containing monooxygenase 1 by (N,N-dimethylamino)stilbene carboxylates
Clement, Bernd,Weide, Matthias,Ziegler, Daniel M.
, p. 599 - 604 (2007/10/03)
(E)-[2-(4-(Dimethylamino)phenyl)vinyl]benzenes bearing a nitrile or carboxyl group in the 2', 3', or 4' position were synthesized and tested for substrate activity with purified pig liver flavin-containing monooxygenase (FMO1). Although the nitrile derivatives were too insoluble to saturate the catalytic site at pH 7.4, they appeared to be substrates with K(m)'s somewhat above their maximum solubility (?0.1 mM) in the assay medium. Of the three carboxylic acid analogs, (E)-4-[2-(4-(dimethylamino)phenyl)vinyl]benzoic acid had no detectable water solubility at pH 7.4, and measurements were restricted to (E)-3-[2-(4-(dimethylamino)phenyl)vinyl]benzoic acid (DS3CO) and (E)-2-[2-(4-(dimethylamino)phenyl)vinyl]benzoic acid (DS2CO). While DS3CO and DS2CO were substrates, they also inhibited FMO1 turnover. DS3CO was the more effective inhibitor, and at 2 mM it inhibited FMO1 and microsomal- catalyzed oxidation of methimazole (N-methyl-2-mercaptoimidazole) by 80-90%. Kinetic studies indicated that the aminostilbene carboxylates were noncompetitive with both the xenobiotic substrate, methimazole, and NADPH. However, inhibition constants calculated from double reciprocal plots of velocity vs NADPH were K(i)(comp) 130 and 150 μM for DS3CO and DS2CO, respectively, whereas the uncompetitive K(i)'s were 10-15 times higher, which suggests that inhibition of NADPH binding may be primarily responsible for inhibition of FMO1 by the aminostilbene carboxylates. This model is also consistent with inhibition of cyclohexanone monooxygenase, a bacterial analog of FMO. DS3CO and DS2CO were again noncompetitive with methimazole but primarily competitive with NADPH. The aminostilbene carboxylates had no detectable effects on activity of pig or rat liver NADPH-cytochrome P450 reductase, which suggests that they are not nonspecific flavoprotein antagonists.
