676121-63-4Relevant academic research and scientific papers
Asymmetric Catalysis with Ethylene. Synthesis of Functionalized Chiral Enolates
Biswas, Souvagya,Page, Jordan P.,Dewese, Kendra R.,RajanBabu
, p. 14268 - 14271 (2015)
Trialkylsilyl enol ethers are versatile intermediates often used as enolate surrogates for the synthesis of carbonyl compounds. Yet there are no reports of broadly applicable, catalytic methods for the synthesis of chiral silyl enol ethers carrying latent functionalities useful for synthetic operations beyond the many possible reactions of the silyl enol ether moiety itself. Here we report a general procedure for highly catalytic (substrate:catalyst ratio up to 1000:1) and enantioselective (92% to 98% major enantiomer) synthesis of such compounds bearing a vinyl group at a chiral carbon at the β-position. The reactions, run under ambient conditions, use trialkylsiloxy-1,3-dienes and ethylene (1 atm) as precursors and readily available (bis-phosphine)-cobalt(II) complexes as catalysts. The silyl enolates can be readily converted into novel enantiopure vinyl triflates, a class of highly versatile cross-coupling reagents, enabling the syntheses of other enantiomerically pure, stereodefined trisubstituted alkene intermediates not easily accessible by current methods. Examples of Kumada, Stille, and Suzuki coupling reactions are illustrated.
Development of highly stereoselective asymmetric 6π- azaelectrocyclization of conformationally flexible linear 1-azatrienes. From determination of multifunctional chiral amines, 7-alkyl cis-1-amino-2-indanols, to application as a new synthetic strategy: Formal synthesis of 20-epiuleine
Tanaka, Katsunori,Kobayashi, Toyoharu,Mori, Hajime,Katsumura, Shigeo
, p. 5906 - 5925 (2007/10/03)
The highly stereoselective asymmetric 6π-azaelectrocyclization was achieved as a general synthetic method based on the reaction between the (E)-3-carbonyl-2,4,6-trienal compounds and the (-)-7-alkyl-cis-l-amino-2-indanol derivatives which are effective chiral amines. The 7-alkyl-substituted 2-indanol moiety of the cyclized products was efficiently removed by the novel manganese dioxide oxidation under remarkably mild conditions, and the method was successfully applied to the formal synthesis of optically active 20-epiuleine.
Synthesis of new chiral auxiliaries for 6π-azaelectrocyclization: 4- and 7-alkyl substituted cis-1-amino-2-indanols
Kobayashi, Toyoharu,Tanaka, Katsunori,Miwa, Junichi,Katsumura, Shigeo
, p. 185 - 188 (2007/10/03)
The synthesis of new chiral auxiliaries, 7-alkyl substituted cis-1-amino-2-indanol derivatives, was established by the Diels-Alder reaction of 1-substituted dienes with cyclopentenone followed by the asymmetric epoxidation of the resulting indene derivatives and then the Ritter reaction. These bulky cis-aminoindanol derivatives are very effective as chiral auxiliaries and nitrogen sources in the asymmetric 6π-azaelectrocyclization. The corresponding 4-alkyl derivative was also prepared using a similar method.
