English
 
Help Privacy Policy Disclaimer
  Advanced SearchBrowse

Item

ITEM ACTIONSEXPORT
  “Site Selective” Formation of Low-Valent Titanium Reagents: An “Instant” Procedure for the Reductive Coupling of Oxo Amides to Indoles

Fürstner, A., Hupperts, A., Ptock, A., & Janssen, E. (1994). “Site Selective” Formation of Low-Valent Titanium Reagents: An “Instant” Procedure for the Reductive Coupling of Oxo Amides to Indoles. The Journal of Organic Chemistry, 59(18), 5215-5229. doi:10.1021/jo00097a024.

Item is

Files

show Files

Locators

show

Creators

show
hide
 Creators:
Fürstner, Alois1, Author              
Hupperts, Achim1, Author              
Ptock, Arne1, Author              
Janssen, Edo2, Author
Affiliations:
1Research Department Fürstner, Max-Planck-Institut für Kohlenforschung, Max Planck Society, ou_1445584              
2Research Department Lehmkuhl, Max-Planck-Institut für Kohlenforschung, Max Planck Society, ou_persistent22              

Content

show
hide
Free keywords: -
 Abstract: Aromatic acylamido carbonyl compounds are readily cyclized to indole derivatives upon treatment with low-valent titanium reagents of the formal oxidation states 0, +1, and +2. Other strong reducing agents such as SmIz and low-valent zirconium, niobium, and tungsten complexes are also capable of effecting such intramolecular alkylidenation reactions of amides. From the preparative point of view these heterocycle syntheses are best effected with an active titanium species which is prepared in the presence of the carbonyl compound upon coordination of TiCl, (n = 3,4) to the oxo amide substrate and reduction of this complex with zinc dust (“instant” method). This procedure turned out to be as effective as the titanium graphite-based methodology previously described but is much easier to perform as all hazardous reagents are avoided. “Instant” cyclizations can also be run in nonethereal solvents such as DMF, ethyl acetate, or acetonitrile and turned out to be compatible with many functional groups. The method was used to cyclize oxo amide 16 to (+Iaristoteline, and it applies nicely to the synthesis of strained indole derivatives, the formation of benzo[b]furans, conventional McMuny reactions of aldehydes and ketones, and the dimerization of alkynes. Metals such as zirconium can also be activated in situ by reduction of ZrCl4 in the presence of a carbonyl compound. On the basis of the results obtained with substrates bearing appropriate structural probes a mechanism for such intramolecular keto-amide coupling processes is proposed. Carbonyl dianions, formed upon two-electron reduction of the keto group, are the most likely reactive intermediates. Electrochemical investigations support this mechanistic interpretation.

Details

show
hide
Language(s): eng - English
 Dates: 1994-04-051994-09
 Publication Status: Published in print
 Pages: 15
 Publishing info: -
 Table of Contents: -
 Rev. Type: Peer
 Identifiers: DOI: 10.1021/jo00097a024
 Degree: -

Event

show

Legal Case

show

Project information

show

Source 1

show
hide
Title: The Journal of Organic Chemistry
  Abbreviation : J. Org. Chem.
Source Genre: Journal
 Creator(s):
Affiliations:
Publ. Info: Washington, D.C., etc. : American Chemical Society [etc.]
Pages: 15 Volume / Issue: 59 (18) Sequence Number: - Start / End Page: 5215 - 5229 Identifier: ISSN: 0022-3263
CoNE: https://pure.mpg.de/cone/journals/resource/954925416967_1