Rieke calcium

Oxidative Addition Reactions of Rieke Calcium with Organic Halides and Some Subsequent Reactions... 

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. 

Chemical Modification of Halogenated Polystyrenes Using Rieke Calcium or Rieke Copper... 

Rieke calcium and copper, which are highly soluble reactive metals, undergo direct oxidative addition to halogenated cross-linked polystyrene resins as shown in Schemes 9.2 and 9.3 [33]. The resulting insoluble polymeric aryl-calcium or aryl-copper reagents can be used to carry out a number of usefiil transformations on the polymers by reacting them with various electrophiles as shown in Table 9.5 and Table 9.6 [22]. 

Rieke calcium is exceptionally highly reactive. Thus, fluorinated, chlorinated, brominated, and chloromethylated cross-linked polystyrene resins are all successfully converted to the corresponding calcium reagents. It should be noted that few metals undei o oxidative addition to aryl fluorides. Thus, it is noteworthy that Ca reacts with / -fluoropolystyrene at room temperature to... 

Scheme 9.2 Modifications of halogenated polystryene resin using Rieke calcium or copper.

Scheme 9.3 Reactions of organocalcium and calcium cuprate reagents prepared from chloromethylated polystyrene and Rieke calcium.

Table 9.6 Reactions of calcium cuprate reagents from chloromethylated polystyrene and Rieke calcium with various electrophiles.

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. 

R. D. Rieke, T.-C. Wu, and L. 1. Rieke 147 HIGHLY REACTIVE CALCIUM FOR THE PREPARATION OF ORGANO-CALCIUM REAGENTS PREPARATION OF 1-ADAMANTYL CALCIUM HALIDES AND THEIR ADDITION TO KETONES 1 -(1 -ADAMANTYLJCYCLOHEXANOL... 

Duncan, J.L., Yang, H., Doan, T., Silverstein, R.S., Murphy, G.J., Nune, G., Liu, X., Copenhagen, D., Tempel, B.L., Rieke, F., Krizaj, D., 2006, Scotopic visual signaling in the mouse retina is modulated by high-affinity plasma membrane calcium extrusion. J Neurosci 26, 7201—7211. 

Wu T-C, Xiong H, Rieke RD (1990) Organocalcium chemistry preparation and reactions of highly reactive calcium. J Org Chem 55 5045-5051... 

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