Wilhelm Fleischhacker

Investigation of Essential Oils of Plectranthus glandulosus Hook f. (Lamiaceae) from Cameroon

Abstract The essential oil of fresh and dried leaves of Plectranthus glandulosus Hook f. [syn. Coleus laxiflorus (Benth.) Roberty] from Cameroon were analysed by GC and GC/MS. The oils were characterized by a high percentage of oxygenated monoterpenes (58.6% and 84.6% respectively) represented by cis-piperitone oxide (3.0% and 35.1%), trans-piperitone oxide (0.5% and 12.6%), fenchone (30.8% and 21.6%) and piperitenone oxide (10.9% and 6.0%). The main monoterpene hydrocarbons were terpinolene (25.2% and 7.7%), limonene (3.2% and 1.7%) and myrcene (2.2% and 1.6%). The sesquiterpene derivatives were found in a very low percentage (< 2.5%), represented mainly by germacrene D (1.4% and 1.0%).

Synthesis and optical properties of the chloroquine enantiomers and their complexes with ferriprotoporphyrin IX in aqueous solution

Chloroquine (CQ) enantiomers were prepared by a novel synthesis starting from either (S)- or (R)-pyroglutamic acid. Light-absorption spectra of CQ and of complexes of ferriprotoporphyrin IX (FP) with CQ were measured in dilute aqueous solutions at pH 7.3 and 11.3. Spectrophotometric titrations at these pH values indicated a mole ratio of FP:CQ of 2:1 for the FP-CQ aggregated complexes. Aqueous solutions of each of the CQ enantiomers (pH 7.3) and of their complexes with FP (pH 11.3) were investigated by circular dichroism (CD). At pH 11.3, the complexes of the two enantiomers showed CD-band extrema of opposite sign at 409–410 nm. CD-titrations at pH 11.3 confirmed a predominant mole ratio of FP:CQ of 2:1 in the complex. The possible origin of the optical activity of the FP-CQ complexes is discussed. Chirality 10:556–563, 1998.

Investigation of the Essential Oil and Headspace of Laggera pterodonta (DC.) Sch. Bip. ex Oliv., a Medicinal Plant from Cameroon

Abstract The essential oils of leaves and flowers of Laggera pterodonta (Asteraceae) from Cameroon were analyzed by GC and GC/MS. The oils were characterized by a high percentage of oxygenated sesquiterpenes (30–80%) and thymol derivatives (4–50%). The major components in the oils were γ-eudesmol (17–45%), α-eudesmol (4–15%), 2,5-dimethoxy-p-cymene (4–50%) and juniper camphor (4–12%). Monoterpenes are found in a high percentage in the flower headspace, represented mainly by γ-terpinene (32%), terpinen-4-ol (14.1%) and β-phellandrene (6%).

Aminoalkohole, 2. Mitt.: Ein Verfahren zur Herstellung enantiomerenreiner pharmakologisch aktiver β-Aminoalkohole

ZusammenfassungDie Reduktion enantiomerenreiner O-MBF- bzw. O-MBE-geschützter Cyanhydrine mit LiAlH4 führt unter Einhaltung definierter Reaktionsbedingungen zu den entsprechenden geschützten Aminoalkoholen, in denen der Anteil der durch Epimerisierung gebildeten Nebenprodukte kleiner als 3% ist. Die Abtrennung der unerwünschten Diastereomere erfolgt im Zuge der Reinigung der Produkte. Durch Schutzgruppenabspaltung mit Salzsäure/Methanol können die enantiomerenreinen Aminoalkohole erhalten werden. Die meist sehr guten Trennfaktoren der O-MBF- bzw. O-MBE-geschützten Verbindungen erlauben für viele Verbindungen sowohl im Cyanhydrin- als auch im Aminoalkoholstadium eine präparative Trennung und machen das Verfahren deshalb vielseitig verwendbar.SummaryA synthesis of β-aminoalcohols is described starting from racemic or enantiomerically pure α-hydroxynitriles which were O-protected using enantiomerically pure acetal type protective groups. Reduction with lithium aluminium hydride yielded O-protected β-aminoalcohols. Whenever diastereomeric O-protected cyanohydrins could not be separated, the mixture was reduced and the resulting O-protected aminoalcohols were separated. Removal of the protective group using hydrogen chloride and methanol yielded enantiomerically pure β-aminoalcohols or their corresponding hydrochlorides.

New benzofuran-type antiarrhythmic compounds related to propafenone

Synthesis of two benzofuran compounds (2a and 2b), which are structu- rally and - by their action as sodium channel blockers - also pharmaco- logically related to propafenone is described

Aminoalkohole, 3. Mitt. Ein Verfahren zur Herstellung von enantiomerenreinen pharmakologisch aktiven N-substituierten β-Aminoalkoholen

ZusammenfassungClorprenalin und Propranolol können mit dem vorgestellten Verfahren in sehr guter Ausbeute aus den O-MBF-geschützten Aminoalkoholen durch reduktive Alkylierung in enantiomerenreiner Form hergestellt werden. Bei der Synthese von enantiomerenreinem Midodrin, bei der in der letzten Stufe gemeinsam mit der O- auch die N-Schutzgruppe (BOC) abgespalten wird, müssen bestimmte Reaktionsparameter (Zeit, Temperatur) präzise eingehalten werden, um eine entsprechende Enantiomerenreinheit der Endprodukte (>95% ee) zu gewährleisten.SummaryA synthesis of N-substituted β-aminoalcohols is described starting from enantiomerically pure O-MBF- or O-MBE-protected β-aminoalcohols which can be preparedvia LiAlH4 reduction of O-protected cyanohydrines.

7,14-Cyclo-dihydro-codeinon

Abstract(5α,9α,13β,14β)-4,5-Epoxy-9-hydroxy-3-methoxy-17-methyl-hasubanan-6-one-hydrochloride (6 a·HCl) reacts with dimethyl sulfate to give the sulfate7 which yields the cyclopropane derivate10 on treatment with aqueous NaOH. The structure of 7,14-cyclo-dihydrocodeinone (10) was established on the basis of1H- and13C-NMR-spectroscopy.

Die katalytische Hydrierung von 14-Brom-codeinon-dimethylacetal

The palladium-catalyzed hydrogenation of2a mainly leads to the new dimeric compounds6,7 and8, beside3b,9, and10. The yield of dimeric compounds is decreased by increasing the volume of the solvent. Under certain conditions9 in 87% yield is formed. The structures and the configuration on C-7 of3b,6,7, and8 are also derived.ZusammenfassungDie katalytische Hydrierung von 14-Brom-codeinondimethylacetal (2a) liefert in erster Linie die drei dimeren Neopinon-acetale (bd6,7) und8, sowie Neopinon-dimethylacetal (3b), Dihydro-codeinon-dimethylacetal (9) und (7R)-7-Hydroxyneopinon-dimethylacetal (10). Die Ausbeuten an Dimeren nehmen bei Vergrößerung des Reaktionsvolumens ab. Bei einer besonderen Ausführung der Hydrierung ist9 in 87proz. Ausbeute zugänglich. Die Strukturen und die Konfiguration an C-7 von6,7,8 und3b werden bewiesen und einige Umwandlungsprodukte beschrieben.

Struktur- und Konfigurationsbeweis für das Diketon aus 14-Bromcodeinon

ZusammenfassungEs wird nachgewiesen, daß den aus 14-Brom-codeinon (1)* bzw. 7-Brom-neopinon-methoperchlorat durch einfache Hydrolyse entstehenden Diketoverbindungen die Struktur und Konfiguration von Δ8(14)-7-Oxo-thebainon (5) bzw. des entsprechenden Methoperchlorats zukommt. Das durch Kondensation von5 mit o-Phenylendiamin entstehende Chinoxalinderivat7 gibt zwei am C-6a diastereomere Dihydroverbindungen (8 und10), wobei8 das Enantiomere des Kondensationsproduktes von Sinomeninon (6) und o-Phenylendiamin darstellt.AbstractThe diketo compounds formed in the hydrolysis of 14-bromocodeinone (1) and 7-bromoneopinone methoperchlorate, resp., have been shown to possess structure and configuration of Δ8(14)-7-oxothebainone (5) and its methoperchlorate, resp. The quinoxaline derivative7, obtained by condensation of5 with o-phenylenediamine, yields two dihydro compounds (8 and10) diastereomeric at C-6a.8 has been found to be the enantiomer of the condensation product obtained from sinomeninone (6) and o-phenylenediamine.

14,17-Cyclonorcodeinondimethylacetal: Ein neues, reaktionsfrudiges Codeinonderivat, II

SummaryIn addition to a short communication describing the synthesis of 14,17-cyclonorcodeinone dimethylacetal1 a [1] we wish to present a simple alternative route together with a selection of some reactions depending on the great reactivity of this highly strained small ring system. The structure of1 a is established by X-ray analysis.