Synthese des racemats eines seco-furoeremophilans aus euryops hebecarpus [1]

Starting with 6-amino-5-cyano-3-methyl benzofuran the structure of a seco-furoeremophilane has been established by synthesis.     

Übergangsmetall-Carbin-Komplexe LXXXVII. Synthese neuer, thermisch stabiler, kationischer Diethylaminocarbin-Komplexes des wolframs

trans-I(CO)₂L₂WCNEt₂ complexes (L₂ = 2,2′-bipyridyl (2,2′-bipy); 1,10-phenanthroline (ophen)) react with PR₃ (R = Me, Et) and thus undergo substitution of the iodine ligand by the phosphine to yield the new, thermostable, cationic carbyne complexes, [(PR₃)(CO)₂L₂WCNEt₂]⁺ I⁻. The ionic character of the compounds has been established from electrical conductivity studies of their solutions. Spectroscopic investigations of the complexes, whose composition has been determined by elemental analysis, indicate that in this reaction the halogen ligand in the trans position has been displaced by the chelate ligand, while the phosphine ligand occupies a cis coordination site, relative to carbyne moiety.     

Über den einfluss von chlor-substituenten auf die bildungstendenz und bindungsverhältnisse des tricarbonyl(buta-1,3-dien)eisen: Tricarbonyl(2,3-dichlorbuta-1,3-dien)eisen und tricarbonyl(2-chlorbuta-1,3-dien)eisen

Frequencies of carbonyl stretching vibrations and relative yields in syntheses of tricarbonyl(2,3-dichlorobuta-1,3-diene)iron and tricarbonyl(2-chlorobuta-1,3-diene)iron are discussed with respect to possible steric effects of chloro-substituents on the formation of tricarbonyl(hexachlorobuta-1,3-diene)iron.     

Synthese des (±)-Oncinotins

(±)-Oncinotin ( 19 ) is synthesized through the crucial intermediates 11 and 15 . By comparison of the synthetic product with natural (?)-oncinotin, it is found that the latter contains an isomeric substance, represented by structure 20 .     

Synthese des (±)-Lasiodiplodins

Synthesis of (±)-Lasiodiplodin The synthesis of the plant growth inhibitor (±)-lasiodiplodin (VII), a 12 membered lactone of a substituted resorcylic acid is described. Condensation of methyl acetoacetate and methyl 11-hydroxy-2-undecenoate followed by treatment of the product with benzyl alcohol lead to the benzyl ether II which was aromatized via the benzeneselenenyl derivative. Methylation of the phenolic hydroxyl in III and conversion of the primary alcohol in the side chain into the secondary alcohol provided the hydroxy ester IV. The corresponding hydroxy acid V was transformed into the S-(2-pyridyl) carbothioate which cyclized under the influence of silver ions to yield 68% of 4-benzyl-lasiodiplodin (VI). Removal of the benzyl group by catalytic hydrogenation gave (±)-lasiodiplodin (VII).     

Über eine Synthese des angulären Di(cyclobuteno)benzols

On a Synthesis of the angular Di(cyclobuteno)benzol In the course of our studies aimed at better understanding the Mills-Nixon effect, we have also prepared the angular di(cyclobuteno)benzene ( 1 ), the synthesis of which has been recently described by another group [3]. Our completely different and essentially simpler synthetic approach will be pointed out. A special pyrolysis apparatus is designed.     

Synthese des Pyrrolizidin-Alkaloides (±)-Trachelanthamidin

Synthesis of the Pyrrolizidine Alkaloid (±)-Trachelanthamidine The important intermediate in the synthesis of the title compound 8 is the diastereoisomer mixture of ethyl 2-[2-(1,3 dioxolan-2-yl)ethyl]-5-oxopyrrolidine-3-carboxylate ( 3a/3b ) which was prepared from nitromethane, acrylaldehyde, and diethyl fumarate (Scheme). Its reduction (NaBH₄, t-BuOH, MeOH) gave exclusively the trans-alcohol 4a , which was converted to the protected pyrrolidine derivative 6 . The deprotection and reduction of 6 gave the pyrrolizidine alkaloid 8 , characterized as its hydrochloride.     

Zur Synthese des 1-Guajacyl-propandiols-(1,3)

Zusammenfassung Einige Darstellungsweisen des 1-Guajacyl-propandiols-(1,3), ausgehend vom Benzylvanilloyl-essigester (VI), der durch verschiedene Hydrierungsschritte in obige Verbindung übergeführt wurde, werden beschrieben. Im Zusammenhang damit werden Resultate japanischer Autoren diskutiert.