Abstract:The naturally occurring ten-membered lactones decarestrictine B (4) and D (5), which lower cholesterol levels, were glycosylated with deoxygenated 2-selenoglycosyl acetates 7 a, 7 b, and glycal 10 (obtained from d-glucose), and glycal 13 (obtained from l-rhamnose). Depending on the glycosylation method employed, the triol decarestrictine D was glycosylated with a high degree of regioselectivity. A set of hybrid structures were yielded by O-deblocking and in most cases reductive removal of a halogen or a phenylselenyl group from C-2 of the glycosides 14 a ± f, 20 a, 20 b, and 24. These hybrids were subjected to preliminary biological tests in which the novel glycoconjugates 15 d and 15 e displayed DNA-binding properties.
Dihydro‐1,2‐oxazine 8 und 1,2‐Oxazine 12 werden aus Nitronsäuren der Addukte aus α‐Nitroolefinen und β‐Dicarbonylverbindungen (6) auf zwei Wegen hergestellt: A) Die Nitronsäuren 6 werden in einer siedenden Lösung von Harnstoff in Ethanol oder Methanol erhitzt. B) Die Nitronsäuren 6 werden mit einer wäßrigen Ammoniumchlorid/Natriumsulfid‐Lösung reduziert. 1H‐NMR‐ und 13C‐NMR‐Untersuchungen beweisen die Konstitutionen. Der Mechanismus wird diskutiert.
cc-und P-Chlor-, P-Benzylmercapto-und P-Tosyloxy-acrylnitril liefern mit Diathylphosphin cis-und trans-P-Diathylphosphino-acrylnitril, dessen Reaktionen untersucht werden. Aus Acrylnitril und Diathylchlorphosphin entsteht ein 1 : I-Additionsprodukt mit der vermutlichen Struktur eines Epiphosphoniumsalzes. *) Teil der Dissertat.
Nitronsauren der Addukte aus a-Nitroolefinen und Acetessigestern reagieren mit CH-aciden Methylengruppen zu 4,5-Dihydro-5-(methylenamino)-3-furancarbonsaureestern 8 . 13C-NMR-Untersuchungen beweisen Struktur 8b. Befunde zum Mechanismus werden mitgeteilt.
Contributions to the Nef Reaction, MI). -4,S-Dihydro-5-(methyleneamino)-3-furancarboxylatesNitronic acids of the adducts of a-nitroolefines and acetoacetates react with compounds with CHacidic methylene groups to yield 4,5-dihydro-5-(rnethyleneamino)-3-furancarboxylates 8. Structure 8b is proved by 13C NMR investigations. Facts supporting the mechanism are reported.
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