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Rieke barium

As barium is in the same periodic row as calcium, it was anticipated that active barium could be prepared by essentially the same approach as used for preparing Rieke calcium. This turned out to be the case, and highly reactive Rieke barium was readily prepared essentially by the identical approach used for preparing Rieke calcium. [Pg.391]

The resulting Rieke barium was found to undergo oxidative addition to a wide variety of organic halides. [Pg.391]

Oxidative Addition of Rieke Barium to Allylic Halides Preparation of Stereochemically Homogeneous Allylic Barium Reagents... [Pg.392]

Xiong and Corey also used Rieke barium in an enantioselective total synthesis of glabrescol, a chiral C2-symmetric pentacyclic oxasqualenoid. The first step is shown in Scheme 10.4 [5]. [Pg.392]

Conditions (a) Rieke barium, THF, -78°C, 1 h (56%) Scheme 10.4 Coupling ofallylic barium reagent . [Pg.393]

The soluble and homogeneous forms [2] of highly reactive metals such as Rieke calcium, barium, or strontium are effective reagents for this type of polymerization. The polymerization failed when insoluble highly reactive metal powders such as Rieke magnesium [31] were used (Equation 9.2). The soluble biphenyl complexes M(biphenyl)2 (M = Ca, Sr, or Ba) were sufficiently active to facilitate polymerization. In contrast only oxidative addition of Mg into the carbon-chlorine bond occurred, and upon workup only a-chlorotolu-ene and a,a-dichlorotoluene were recovered quantitatively as products after 24 h of reflux. No coupling reaction or polymerization occurred. [Pg.384]


See other pages where Rieke barium is mentioned: [Pg.391]    [Pg.391]    [Pg.392]    [Pg.392]    [Pg.391]    [Pg.391]    [Pg.392]    [Pg.392]    [Pg.374]    [Pg.175]    [Pg.177]   
See also in sourсe #XX -- [ Pg.391 ]




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