0000000000379460
AUTHOR
Reijo Sillanpaeae
Preparation and Structure of Bicycloalkane-Condensed Aryldiaziridines Accompanied by Pyrimidines
Di-exo- and di-endo-2-aminonorbomane/enemethanamines 1-3, di-exo-oxanorbomene derivative 4 and cis-cyclohexane and trans-4-cyclohexene analogues 5, 6 were reacted with p-chlorobenzaldehyde in the presence of N-bromosuccinimide in dichloromethane. Via the reactions of 1-6, condensed diaziridines 7-12 accompanied by pyrimidine derivatives 13-16 were prepared after isolation with column chromatography. The mechanisms proposed for alternative transformations were supported by DFT calculations. The structures of the new compounds were proved by IR and NMR spectroscopy and, for 7, 9 and 12, also by means of X-ray crystallography.
Hybrid compounds generated by the introduction of a nogalamycin-producing plasmid into Streptomyces argillaceus
The combination of genetic material from different antibiotic-producing organisms is a versatile and ever-expanding approach for the production of novel, hybrid compounds possessing bioactivity. The introduction of a plasmid (pSY21b) derived from Streptomyces nogalater and encoding PKS for nogalamycin production into the host strain S. argillaceus A43 led to the production of three new compounds in addition to the normally produced mithramycin. The new compounds are hybrids in the sense that they share features associated with the genes of both the host and the introduced plasmid. The structural elucidation of the novel compounds relied primarily on NMR spectroscopy, which revealed the thre…
Facile Regio- and Diastereoselective Syntheses of Hydroxylated2-Aminocyclohexanecarboxylic Acids
By means of total regio- and diastereoselective functionalizations of cis- and trans-2-amino-4-cyclohexenecarboxylic acid derivatives 1, 9, 12 and 16, isomers of 2-amino-4-hydroxycyclohexanecarboxylic acid 8 and 11, and 2-amino-5-hydroxycyclohexanecarboxylic acid 15 and 19 were prepared in good yields, via 1,3-oxazine or γ-lactone intermediates. The enantiomers of 8 and 15 were also prepared by the same pathway, resulting in products with ee > 99 %. The structures, stereochemistry and relative configurations of the synthesized compounds were proved by NMR, using some key vicinal couplings and characteristic NOEs. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Synthetic transformation of hydroxymatairesinol from Norway spruce (Picea abies) to 7-hydroxysecoisolariciresinol, (+)-lariciresinol and (+)-cyclolariciresinol
We have developed a method for the transformation of hydroxymatairesinol to optically pure (+)-lariciresinol and (+)-cyclolariciresinol via the hitherto unreported lignan 7-hydroxysecoisolariciresinol. The two naturally occurring isomers of hydroxymatairesinol were reduced with LiAlH4 to a mixture of two epimers of 7-hydroxysecoisolariciresinol, which were further selectively transformed to (+)-lariciresinol and (+)-cyclolariciresinol by an acid catalysed intramolecular cyclisation reaction. The structure of the major isomer of 7-hydroxysecoisolariciresinol was confirmed by X-ray crystallography and thereby also the absolute configurations of the two isomers of hydroxymatairesinol were unam…
Synthesis of bi- and tricyclic β-lactam libraries in aqueous medium
Water as a solvent is not only inexpensive and environmentally benign, but may allow good reactivity. The present work focuses on the application of a modified Ugi reaction, i.e. the Ugi four-centre three-component reaction (U-4C-3CR), in aqueous medium to construct β-lactam libraries. All the attempted reactions could be successfully performed in water. The reaction conditions under which the precipitation process was effective were investigated; no further work-up or purification was necessary. In several cases when less water-soluble β-amino acids were used, the precipitated products were isolated easily by simple filtration. In other cases, evaporation of the solvent was appropriate for…