98078-15-0Relevant articles and documents
Intramolecular cycloaddition of O-tert-butyldimethylsilyloximes in the presence of BF3-OEt2
Tamura, Osamu,Mitsuya, Takahiro,Huang, Xin,Tsutsumi, Yoshiyuki,Hattori, Sanae,Ishibashi, Hiroyuki
, p. 10720 - 10725 (2007/10/03)
Intramolecular cycloaddition of novel 1,3-dipoles, N-boranonitrones, was examined. Treatment of O-tert-butyldimethylsilyloximes 9-12 having olefin moieties with 2 equiv of BF3·OEt2 generated N-boranonitrones, which underwent intramolecular cycloaddition to afford N-nonsubstituted cycloadducts 16 (and/or 18) after extractive workup. Despite the Lewis-acidic conditions, the olefin geometry of the substrates was retained in the cycloadducts in the present cycloaddition. The electronic nature of the N-boranonitrones appeared to be electrophilic. In the case of substrate 11c, having an electron-donating methyl group at an internal position of the olefin moiety, the cycloaddition gave the bridged cycloadduct 18b. The cycloaddition proceeded at relatively low temperature, and the diastereoselectivity was high.
Synthesis of 2-phenyl-2-cycloalkenones via palladium-catalyzed tandem epoxide isomerization-intramolecular aldol condensation
Kim, Ji-Hyun,Kulawiec, Robert J.
, p. 3107 - 3110 (2007/10/03)
We have extended the scope of our palladium-catalyzed tandem epoxide isomerization/aldol condensation reaction to encompass intramolecular condensations, which provide facile access to conjugated cycloalkenones from epoxy aldehydes or diepoxides. For example, reaction of 5,6-epoxy-6- phenylhexanal with Pd(OAc)2-PBu3 catalyst in the presence of NaHCO3 and 3A molecular sieves forms 2-phenyl-2-cyclopentenone (80%). Similarly, 1,2;5,6-diepoxy-1-phenylhexane affords 3-methyl-2-phenyl-2-cyclopentenone (72%). The observation of dicarbonyl intermediates (e.g., 1-phenyl-2,5- hexanedione in the latter case) demonstrates that the reaction proceeds via Pd-catalyzed isomerization of the diepoxide to the diketone, followed by base-catalyzed aldol condensation.
Intramolecular anodic olefin coupling reactions: A useful method for carbon-carbon bond formation
Hudson, Christine M.,Marzabadi, Mohammad R.,Moeller, Kevin D.,New, Dallas G.
, p. 7372 - 7385 (2007/10/02)
The utility of intramolecular anodic olefin coupling reactions for effecting carbon-carbon bond formation has been examined. All of the successful cyclizations studied utilized either an alkyl or silyl enol ether as one of the participating olefins. The e