Magnesium alkylating agents

Reaction of Various Aldimine and Ketimine Magnesium Bromide Salts with Alkylating Agents in Tetrahydrofuran... 

Standard Nd-based catalysts comprise binary and ternary systems. Binary systems consist of Nd chloride and an aluminum alkyl or a magnesium alkyl compound. In ternary catalyst systems a halide free Nd-precursor such as a Nd-carboxylate is combined with an Al- or Mg-alkyl plus a halide donor. By the addition of halide donors to halide-free catalyst systems catalyst activities and cis- 1,4-contents are significantly increased. In quaternary catalyst systems a solubilizing agent for either the Nd-salt or for the halide donor is used in addition to the components used in ternary systems. There are even more complex catalyst systems which are described in the patent literature. These systems comprise up to eight different catalyst components. 

As discussed in Sects. 2.1 and 2.2.8 control of molar mass is an important aspect in the large-scale polymerization of dienes. In Nd-catalyzed polymerizations the control of molar mass is unique amongst Ziegler/Natta catalyst systems as standard molar mass control agents such as hydrogen, 1,2-butadiene and cyclooctadiene which are well established for Ni- and Co-systems do not work with Nd catalysts [82,206,207]. The only known additives which allow for the regulation of molar mass without catalyst deactivation are aluminum alkyls, magnesium alkyls, and dialkyl zinc. 

Preparative Methods the synthesis of this compound was first reported by methylation of (R)-(+)-t-Butyl 2-(p-Tolylsulfinyl)acetate via enolate generation with lithium bases such as n-Butyllithium or t-Butyllithium at 0 °C and with only lodomethane as the alkylating agent (eq 1). The diastereomeric ratio was shown by H NMR to be 50 50 with BuLi and 42 58 with t-BuLi. The title compound was also prepared from (-)-(1R,2S,5R)-Menthyl (S)-p-Toluenesulfinate and the magnesium enolate of t-butyl propionate in 68% yield as a 1 1 ratio of the two possible diastereomers (eq 2). ... 

Alkylations Allyl and benzyl acetates serve as adequate alkylating agents to nucleophiles such as silyl ketene acetals when magnesium triflimide is used to activate them. In most cases this reagent is superior to magnesium perchlorate. 

Alkylating agents that have been used include organo compounds of alkali metals, magnesium, aluminum, mercury, and zinc. The following equations illustrate some examples ... 

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