Metal-free Bronsted acids catalyzed synthesis of functional 1,4-dihydropyridines

International audienc

Synthesis of Tetrahydroisoquinoline Alkaloids and Related Compounds through the Alkylation of Anodically Prepared α-Amino Nitriles

International audienceα-Amino nitrile 2a was conveniently prepared in two individual steps from chiral hexafluorophosphate salt isoquinolinium (−)-8b including anodic cyanation as an efficient means to activate the sp3 C1–H bond of the THIQ nucleus. The lithiation of 2a was carried out in THF at −80 °C in the presence of LDA to produce a stable α-amino carbanion which was condensed on a large variety of alkyl halides. The resulting quaternary α-amino nitriles were subjected to a stereoselective reductive decyanation in ethanol in the presence of NaBH4 as the hydride donor to yield N-Boc-1-alkyl-THIQs (+)-10a–g in up to 97:3 er’s after removal of the chiral auxiliary group. Examination of the ORTEP view of THIQ (+)-1f revealed that the newly created stereogenic center had an absolute S configuration. Likewise, (−)-xylopinine was synthesized in four workup steps in an overall 63% yield from α-amino nitrile (+)-2b. In this process, crystallization of an enantioenriched mixture (90:10) of (−)-norlaudanosine with 1 equiv of (−)-N-acetyl-l-leucine afforded the leucinate salt (+)-13 (99:1 dr). Similarly, (+)-salsolidine was displaced from its (−)-DBTA salt (−)-12 in 99:1 er, which was determined by proton and carbon NMR spectroscopy in the presence of thiophosphinic acid (+)-14 as the chiral solvating agent

Ferroceneboronic Acid and Derivatives Synthesis, Structure, Electronic Properties, and Reactivity in Directed C-H Bond Activation

International audienceKnown since 1959, ferroceneboronic acid (1) and its derivatives have been mainly used as polyol sensors and in cross-coupling reactions. However, a literature survey revealed that there is not a paper describing the full characterization of ferroceneboronic acid derivatives and that useful boron protecting groups have not been studied in the ferrocene series. Here, we present an optimized multigram-scale synthesis of the known ferroceneboronic acid (1) using a phase-switch purification process. It was furthermore functionalized to reach the diaminonaphthalene (FcB(dan), 15), anthranilamides (FcB(aam), 16; FcB(Me-aam), 17 and 18), potassium trifluoroborate (FcBF3K, 19), triolborate (FcB(triolborate), 20) and N-methyliminodiacetic acid (FcB(MIDA), 21) derivatives. Their structures were unambiguously assigned by NMR and X-ray analysis, and the data collected provided a general overview of the electronic and structural features of these compounds. From the data obtained, B(dan) and B(amm) were classified as electron-withdrawing groups, whereas trifluoroborate and triolborate behave as electron-donating groups. We report the first catalytic silylation of ferrocene C-H bonds to access di- and trisubstituted derivatives. Catalytic borylation was also attempted, highlighting a switch in regioselectivity that was unambiguously assigned by X-ray analysis

Anodic cyanation of (S)-(–)-1-(1-phenetyl)piperidine: an expedition synthesis of (S)(+)-Coniine

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Synthesis of tetrahydroisoquinoline alkaloids via anodic cyanation as key step.

International audienc

Bronsted acids catalyzed synthesis of Pyrans via a formal [3+3] cycloaddition

International audienc

Metal-free Bronsted Acids Catalyzed Formal [3+3] Annulation Straightforward Synthesis of Dihydro-2H-Chromenones, Pyranones and Tetrahydroquinolinones

International audienc

Synthesis of Alkaloids of galipea officinalis by Alkylation of an Α- aminonitrile

International audienc

Lethality of Red Imported Fire Ant Venom to Argentine Ants and Other Ant Species

International audienc