A Novel Synthesis of 1-Aryl-9-alkyl-2, 3, 3a, 4, 9, 9a-hexahydro-1H-pyrrolo[2, 3-b] quinoxalines by lithium aluminium hydride reduction of N-phenyl-1-benzimidazolyl-succinimides

The N-substituted 1-benzimidazolyl-succinimides 6a – v (Scheme 1, Table 1 and 2) have been prepared by the reaction of benzimidazole and its derivatives with maleimides. Reduction of the N-cyclohexyl and N-cyclo-octyl substituted 1-benzimidazolyl-succinimides 6i – k with lithium aluminium hydride gives the normally expected substituted (N-alkyl-3-pyrrolidinyl)benzimidazoles 14i – k . However by LiAlH₄-reduction of the N-phenyl substituted 1-benzimidazolylsuccinimides 6a – h mainly the 1-aryl-9-alkyl-2, 3, 3a, 4, 9, 9a-hexahydro-1H-pyrrolo[2, 3-b]quinoxalines 7a – h are obtained. The mechanism of this unusual reduction has been elucidated.     

Monothiohydrochinonäther als Vermittler einer oxydativen Synthese von Adenosin-di- und-triphosphat (ADP undATP)

Zusammenfassung Durch Oxydation von S-Methylmonothio-durohydrochinon (1) oder S-Methylmonothio-2,3-dimethyl-1,4-naphthohydrochinon (2) mit Brom in wasserfr. Pyridin entstehen aus den Tetrabutyl-ammoniumsalzen der Phosphorsäure und des Adenosinmonophosphats: Adenosindiphosphat (ADP) und Adenosintriphosphat (ATP), aus Phosphat und Adenosindiphosphat: etwa 25%ATP.

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By oxidation with bromine of S-methylmonothio-durohydroquinone (1) or of S-methylmonothio-2,3-dimethyl-1,4-naphthohydroquinone (2) in dry pyridine in presence of tetrabutyl-ammonium salts of inorganic phosphate and of adenosine-monophosphate, adenosine-diphosphate (ADP) and adenosine-triphosphate (ATP) are formed. Inorganic phosphate andADP give 25%ATP under the same conditions.

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Fritz Wessely mit freundschaftlichem Gruß zum 70. Geburtstag gewidmet.     

The Synthesis of Spiro[tetrahydroisoquinoline-piperidines] and related compounds

The reaction of 3,4-dimethoxyphenethylamine with some cyclic aminoketones in the presence of polyphosphoric acid afforded 1-spiro-tetrahydroisoquinolines. A two-step procedure starting from veratrylamine and amino-ketones gave 3-spiro-tetrahydroisoquinolin-4-ones. The Schmidt rearrangement of 5,6-dimethoxy-3-spiro-indan-1-ones yielded 4-spiro-tetrahydroisoquinolin-1-ones.     

Rearrangement of Cephem Bromohydrins to Thiazepine Derivatives

A new rearrangement of cephem bromohydrins 2 – 5 to thiazepine derivatives 7 – 8 is described. The structure of the rearrangement product is established by an independent synthesis. The probable mechanism of the above rearrangement is discussed.     

Methine (CH) transfer via a chlorine atom abstraction/benzene-elimination strategy: molybdenum methylidyne synthesis and elaboration to a phosphaisocyanide complex

Methine (CH) transfer to an open coordination site was achieved in one pot by titanium(III) abstraction of Cl from 7-chloronorbornadiene, radical capture by Mo, and benzene extrusion. This efficient Mo methylidyne synthesis permitted elaboration to an anionic phosphaisocyanide derivative upon deprotonation, functionalization with dichlorophenylphosphine, and ultimate reduction.     

Lewis Acid Accelerated Aryl Ether Bond Cleavage with Nickel: Orders of Magnitude Rate Enhancement Using AlMe3

Study of the kinetics of intramolecular aryl ether C?O bond cleavage by Ni was facilitated by access to a family of metal complexes supported by diphosphines with pendant aryl‐methyl ethers. The nature of the aryl substituents was found to have little effect on the rate of cleavage. In contrast, soluble Lewis acidic additives accelerate the aryl ether cleavage dramatically. The effect of AlMe ₃ was studied in detail, and showed an increase in rate by several orders of magnitude. Low temperature NMR spectroscopy studies demonstrate quantitative coordination of ether to Al. From the Lewis acid‐bound precursor, the activation parameters for ether cleavage are significantly lower. These findings provide a mechanistic basis for milder catalyst design for the activation of strong bonds.