69626-40-0Relevant academic research and scientific papers
Fe-Catalyzed Cycloisomerization of Aryl Allenyl Ketones: Access to 3-Arylidene-indan-1-ones
Teske, Johannes,Plietker, Bernd
, p. 2257 - 2260 (2018/04/27)
A cycloisomerization of aryl allenyl ketones to 3-arylidene-indan-1-ones using a cationic Fe-complex as a catalyst is reported. The catalyst opens a synthetically interesting reaction pathway to this surprisingly underrepresented class of indanones that are not accessible using alternative catalytic systems.
Metal-catalyzed 1,2-shift of diverse migrating groups in allenyl systems as a new paradigm toward densely functionalized heterocycles
Dudnik, Alexander S.,Sromek, Anna W.,Rubina, Marina,Kim, Joseph T.,Kel'in, Alexander V.,Gevorgyan, Vladimir
, p. 1440 - 1452 (2008/10/09)
A general, mild, and efficient 1,2-migration/cycloisomerization methodology toward multisubstituted 3-thio-, seleno-, halo-, aryl-, and alkyl-furans and pyrroles, as well as fused heterocycles, valuable building blocks for synthetic chemistry, has been developed. Moreover, regiodivergent conditions have been identified for C-4 bromo- and thio-substituted allenones and alkynones for the assembly of regioisomeric 2-hetero substituted furans selectively. It was demonstrated that, depending on reaction conditions, ambident substrates can be selectively transformed into furan products, as well as undergo selective 6-exo-dig or Nazarov cyclizations. Our mechanistic investigations have revealed that the transformation proceeds via allenylcarbonyl or allenylimine intermediates followed by 1,2-group migration to the allenyl sp carbon during cycloisomerization. It was found that 1,2-migration of chalcogens and halogens predominantly proceeds via formation of irenium intermediates. Analogous intermediate can also be proposed for 1,2-aryl shift. Furthermore, it was shown that the cycloisomerization cascade can be catalyzed by Bransted acids, albeit less efficiently, and commonly observed reactivity of Lewis acid catalysts cannot be attributed to the eventual formation of proton. Undoubtedly, thermally induced or Lewis acid-catalyzed transformations proceed via intramolecular Michael addition or activation of the enone moiety pathways, whereas certain carbophilic metals trigger carbenoid/oxonium type pathway. However, a facile cycloisomerization in the presence of cationic complexes, as well as observed migratory aptitude in the cycloisomerization of unsymmetrically disubstituted aryl- and alkylallenes, strongly supports electrophilic nature for this transformation. Full mechanistic details, as well as the scope of this transformation, are discussed.
Metal-catalyzed [1,2]-alkyl shift in allenyl ketones: Synthesis of multisubstituted furans
Dudnik, Alexander S.,Gevorgyan, Vladimir
, p. 5195 - 5197 (2008/03/27)
(Chemical Equation Presented) Even fused furans can be prepared by cycloisomerization of substituted allenyl ketones. The cascade reaction involves a [1,2]-migration of alkyl or aryl groups in allenyl ketones as the key step. Facile reaction in the presence of cationic complexes, as well as migratory aptitude in the cycloisomerization of unsymmetrically substituted allenes, strongly supports an electrophilic mechanism for this transformation.
