α-Amino nitrile 2a was conveniently prepared in two individual steps from chiral hexafluorophosphate salt isoquinolinium (-)-8b including anodic cyanation as an efficient means to activate the sp(3) C1-H bond of the THIQ nucleus. The lithiation of 2a was carried out in THF at -80 °C in the presence of LDA to produce a stable α-amino carbanion which was condensed on a large variety of alkyl halides. The resulting quaternary α-amino nitriles were subjected to a stereoselective reductive decyanation in ethanol in the presence of NaBH4 as the hydride donor to yield N-Boc-1-alkyl-THIQs (+)-10a-g in up to 97:3 er's after removal of the chiral auxiliary group. Examination of the ORTEP view of THIQ (+)-1f revealed that the newly created stereogenic center had an absolute S configuration. Likewise, (-)-xylopinine was synthesized in four workup steps in an overall 63% yield from α-amino nitrile (+)-2b. In this process, crystallization of an enantioenriched mixture (90:10) of (-)-norlaudanosine with 1 equiv of (-)-N-acetyl-l-leucine afforded the leucinate salt (+)-13 (99:1 dr). Similarly, (+)-salsolidine was displaced from its (-)-DBTA salt (-)-12 in 99:1 er, which was determined by proton and carbon NMR spectroscopy in the presence of thiophosphinic acid (+)-14 as the chiral solvating agent.
We have recently reported the antibacterial activity of the essential oils of the stems and the seeds of the endemic species Pituranthos scoparius (Coss. & Dur) Schinz (=Deverra scoparia Coss.& Dur), commonly known as "guezzah" [1]. It is a Saharian species [2] used in traditional medicine for the treatment of asthma and rheumatism [3,4] and in food as a flavoring [3]. Two isocoumarins have been reported from the roots of Pituranthos scoparius [5]. To our knowledge, the aerial parts of this plant have not been the subject of any study. We report here, for the first time, the identification and the antibacterial activity of the flavonoids of the aerial parts of Pituranthos scoparius.Pituranthos scoparius, an endemic species of the Pituranthos genus (Apiaceae), was collected from Ghardaia in April 2003. The plant material was authenticated by Prof. Gerard De Belair (University of Annaba, Algeria) and a voucher specimen (ZKNAPs04/01) was deposited at the Herbarium of the Faculty of Sciences, University Mentouri-Constantine and at the Musee Botanique de la ville d'Angers, France (MBAng2005.13).Air-dried and powdered aerial parts (1 kg) of Pituranthos scoparius were macerated in a methanolic solution (70%), the residue was filtered, concentrated, then successively extracted with petroleum ether, dichloromethane, ethyl acetate and n-butanol. The butanolic extract was concentrated under reduced pressure and column chromatographed on polyamid SC6 with a gradient of toluene-MeOH with increasing polarity. Fraction F 3 was chromatographed on silica gel preparative TLC plates eluted with the system ethylacetate-formic acid-H 2 O (8:1:1), affording compounds 1-3. Fractions F 5 and F 7 were subjected to preparative TLC on polyamid DC6 using H 2 O-MeOH-methylethyl ketone-acetylacetone (13:3:3:1) and flash column chromatography purification with Sephadex LH-20 eluted with methanol, leading to two compounds 4, 5.Acid Hydrolysis. The pure compounds were treated with 2 M HCl at 100°C for 1 h. The hydrolysates were extracted with EtOAc and the aglycones were identified by their UV spectra in methanol and by comparison of their R f with authentic samples.Sugars were identified in the aqueous residue by comparison with authentic samples on silica gel TLC impregnated with 0.2 M NaH 2 PO 4 , solvent Me 2 CO-H 2 O (9:1) revealed with aniline malonate.Compound 1, C 21 H 20 O 10 , mp 227-228°C identified as apigenin 7-O-glucoside or apigetrin [6]. Compound 2, C 21 H 20 O 9 , mp 284°C identified as apigenin 7-O-rhamnoside [6, 7]. Compound 3, C 28 H 32 O 16 , mp 171-173°C. UV (λ max , nm), MeOH: 356, 300sh, 254; +NaOH: 412, 329, 275; + AlCl 3 : 396sh, 361, 300, 267; +HCl: 402, 359, 302sh, 267; +NaOAc: 382, 320, 273; +H 3 BO 3 : 359, 305sh, 270sh, 259.FAB + -MS (m/z): 624 [M+H] + . 1 H NMR (250 MHz, CD 3 OD, δ, ppm, J/Hz): 7.92 (1H, d, J = 2.0, H-2′), 7.68 (1H, dd, J = 8.5, J = 2.0, H-6′), 6.92 (1H,d, J = 8.5, H-5′), 6.40 (1H, d, J = 2.0, H-8), 6.25 (1H, d, J = 2.0, H-6), 5.25 (1H, d, J = 7.5, H-1″glucose), 4.50 (1H, d, J = 1.2, H-1′″rhamnose...
In the title compound, C16H12Cl2O2, the dichlorophenyl and methoxyphenyl groups are linked by a prop-2-en-1-one group. The C=C double bond is trans configured. The molecule is not planar, as can be seen from the dihedral angle of 6.21 (7)° between the planes of the two rings. The crystal structure can be described by two types of crossed layers which are parallel to (110) and (10).
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