Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
Collection
Keywords
Publisher
Years
  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 68 (1985), S. 1828-1834 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Synthesis of Some 8-Substituted 2-Methyl-1,2,3,4-tetrahydroisoquinolinesA general route to 8-substituted tetrahydroisoquinolines is exemplified by the preparation of the 2-methyl-1,2,3,4-tetrahydroisoquinolin-8-ol (11), the -8-carbaldehyde oxime (12) and the -8-carbonitrile (13). It involves the conversion of isoquinoline (1) by partially modified Steps 1, 2, 3, and 5 (see the Scheme) into the 5-bromo-8-nitro derivative 5, reduction of the latter to the 8-amino derivative 8 and replacement of the NH2-group with an appropriate substituent by a Sandmeyer-like reaction. The selective reductions of the N-containing ring in 6 (Steps 5, 6, and 8) and of the NO2-group in 5 (Steps 4 and 7) were also studied.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 2
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Beitrag zum Problem der nucleophilen Substitutionsreaktionen am Kohlenstoffatom kleinerer Ringe mit Retention der Konfiguration.Mit Natriumiodid und mit Tetraäthylammoniumacetat in Aceton findet auch unter energischen Bedingungen keine nukleophile Substitution des Bromatoms in 4-endo-Brom-1,3,5,7-tetramethyl-anti-tricyclo[5.1.0.03,5]octane-2,6-dion (10) statt, obschon bei 10 - nach neueren Anschauungen - gute Voraussetzungen für eine solche Reaktion vorhanden sein sollten. Dies bestätigt die bekannte Trägheit von Dreiring-Kohlenstoffatomen gegenüber SN2-Reaktionen und erhöht die Wahrscheinlichkeit, dass trotz der verwendeten Bedingungen die relativ schnellen Substitutionen der Bromatome in den Ketonen 6 und 7 durch Acetat unter Retention der Konfiguration nicht SN2-Reaktionen sind. Ein Alternativmechanismus mit vorübergehender Öffnung des Dreirings wird für diese Umwandlungen in Betracht gezogen, und zwar 6 → 11 → 8 und 7 → 12 → 9.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: How valid is the proof of existence of intermediates with pentacoordinated C-atoms in aliphatic SN2-reactions?Retention of configuration in the preparative conversion of cis-3-ethoxycyclobutylbrosylate (4) with sodium iodide and with lithium bromide in boiling acetone for 5 days to cis-3-ethoxycyclobutyliodide (6) and bromide (8), respectively, has been published by Ugi et al. to be the basis of a proof that species with pentacoordinated C-atoms exist sufficiently long during aliphatic SN2-reactions that they can undergo ligand reorganizations.It is now shown that the conditions used lead to a thermodynamic control, inasmuch as the cis- and trans-halides 6 and 7, as well as 8 and 9 isomerize to ∼2:1 equilibrium mixtures. Furthermore it is shown that the reaction of kinetic control occurs with inversion, inasmuch as the trans-: cis-halide ratio during the course of the reaction starts with high values and falls slowly to the equilibrium.Thus the nucleophilic substitutions on the examined four-membered ring system do not contravene previous experience with other aliphatic and alicyclic systems, so that the existence of pentacoordinated carbon species as intermediates in aliphatic SN2-reactions cannot be considered as proven.
    Type of Medium: Electronic Resource
    Signatur Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...