200615-25-4Relevant academic research and scientific papers
Coupling-isomerization synthesis of chalcones
Braun, Roland U.,Ansorge, Markus,Mueller, Thomas J. J.
, p. 9081 - 9094 (2007/10/03)
The Sonogashira coupling of electron-deficient (hetero)aryl halides 1 and (hetero)aryl or alkenyl 1-propargyl alcohols 2 does not terminate at the stage of the expected internal propargyl alcohols, but rather gives rise to the formation of α,β-unsaturated ketones 3 with a variety of acceptor substituents. This new domino reaction, a coupling-isomerization reaction (CIR), can be rationalized as a sequence of rapid Pd/Cu-catalyzed alkynylation followed by a slow amine-base-catalyzed propargyl alcohol-enone isomerization. Performing the CIR in deuterated protic solvents or with a selectively deuterated propargyl alcohol revealed that the base-catalyzed isomerization step proceeds through a formal 1,3-H shift with minimal H/D exchange with the surrounding solvent. Additionally, 19F NMR kinetic measurements on the isomerization step with the fluorinated propargyl alcohol 4r support the mechanistic rationale.
Julia-Colonna asymmetric epoxidation reactions under non-aqueous conditions: Rapid, highly regio- and stereo-selective transformations using a cheap, recyclable catalyst
Allen, Joanne V.,Bergeron, Sophie,Griffiths, Matthew J.,Mukherjee, Shubhasish,Roberts, Stanley M.,Williamson, Natalie M.,Wu, L. Eduardo
, p. 3171 - 3179 (2007/10/03)
The asymmetric oxidation of some enones (Table 1), selected dienones 3-5, and a trienone 13 is accomplished using poly-L-leucine or poly-D-leucine and urea hydrogen peroxide under non-aqueous conditions. One of the resultant epoxy ketones 6 has been converted into the δ-lactones 19 and 22.
Stereoselective epoxidation of electron poor dienes using poly(L-leucine)
Allen, Joanne V.,Cappi, Michael W.,Kary, Pierre D.,Roberts, Stanley M.,Williamson, Natalie M.,Wu, L. Eduardo
, p. 3297 - 3298 (2007/10/03)
Poly(L-leucine) catalysed oxidation of dienes 2, 3, 10, 16 and 18 and the triene 17 furnishes the corresponding epoxides 4, 5, 11, 19, 21 and 20 respectively in good to excellent yield and in states of high optical purity. Some regioselective reactions of the saturated epoxy ketones 5 and 11 are described.
