Rhodium carbenoid-initiated Claisen rearrangement: scope and mechanistic observations.
[formula: see text] It has been shown that alpha-diazoketones react with allylic alcohols in the presence of Rh(II) catalysts to furnish intermediate enols which subsequently undergo Claisen rearrangement to alpha-hydroxyketones. Herein we report (1) studies into the mechanism of this transformation which establish that Claisen rearrangement is neither rhodium- nor acid-catalyzed but a reaction intrinsic to the intermediate enols that proceeds at a rate governed by enol substituents (R3, R4, R5) and (2) the reaction of alpha-diazoketones with propargylic alcohols and preliminary investigations into its scope and mechanism.
Wood,Moniz
p. 371 - 374
(2008/02/13)
Facile preparation of allenic hydroxyketones via rearrangement of propargylic alcohols
(equation presented) Treatment of tertiary propargylic alcohols 13 with 3-diazo-2-butanone 6 and catalytic dirhodium tetraacetate in benzene gave good yields of the diastereomeric allenic hydroxyketones 14, with, in some cases, good diastereocontrol. Thes
Jung, Michael E.,Pontillo, Joseph
p. 367 - 369
(2008/02/11)
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