R-Butylmagnesium chloride

Addition of RMgBr to nitriles. Grignard reagents react with nitriles slowly if at all, but even r-butylmagnesium chloride will add to nitriles in refluxing THF when catalyzed by a copper(I) salt. The adduct can be converted to a ketimine by anhydrous protonation, to a primary amine by reduction (Li/NH,), or to a ketone by hydrolysis. The actual reagent may be a cuprate such as R3Cu(MgX)2. 

Bouveault reactionDMF is recommended for formylation of tertiary Grig-nard reagents. Thus pivaldehyde can be obtained in 57-61% yield by reaction of r-butylmagnesium chloride with twofold excess of DMF in ether. 

Preparation of Chiral Sulfinates. Optically active sulfinates can be prepared by reaction of a symmetrical sulfite with t-Butylmagnesium Chloride in the presence of an optically active amino alcohol. The best enantioselectivity has been observed using quinine as the optically active amine (eq 2)3 An alternative approach to this new enantioselective asymmetric synthesis of alkyl t-butylsulfinates would be reaction of a racemic sulfinate with r-butylmagnesium chloride complexed by optically active alkaloids (eq 3). In this case, kinetic resolution of the racemic sulfinate leads to an optically active sulfinate and an optically active sulfoxide. 

Temperature effects on the equilibrium between monomeric complexes have also been documented. An H-NMR investigation of r-butylmagnesium chloride in either THF or diethyl ether showed that low temperature shifts the equilibrium toward the dialkyl complex [18]. 

Grignard reagents add to enynes with electron-donor substituents in the allylic position. The highly hindered olefin in Eq. (10) gave simple addition of r-butylmagnesium chloride [21]. 

Reactions which have rate-determining ET have transition states with charge development and should be accelerated in the more polar solvent THE. Since the various coordination equilibria existing in the reaction mixtures are seriously shifted, reactivity changes have to be carefully analysed. Although the ET reaction with azobenzene is accelerated in THE. the ET reaction between r-butylmagnesium chloride and di-/-butylperoxide is extremely slow in THE 4.ij. 

Attempts ha e been made to correlate the viscosity of the solvent with the product distribution and the behaviour of radical probes in the reaction of r-butylmagnesium chloride w ith benzophenone 137). 

The two diastereoisomers of (134) can be readily resolved by column chromatography and react in THF with a 3 -0-acetylnucleoside in the presence of r-butylmagnesium chloride to give a dinucleoside methylphosphonate in about 65% yield with inversion of configuration (Scheme 22). When the reaction was repeated in pyridine a higher yield (- 80%) was obtained, but a considerable amount of epimerisation was observed. 

The nature of the polymerization initiated by r/-butylmagnesium chloride is still subject to some controversy. Initially Guyot and Tho [197], stated that while there was no direct evidence for an anionic polymerization mechanism, such a process was indicated by the nature of the end groups of the polymer chain, the high degree of crystallinity of the resin formed, and its low molecular weight. 

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