Grignard reagents theoretical studies

Thus, early theoretical and experimental studies of low-temperature reactions in the magnesium-organic halide films allowed one to formulate the problem of obtaining cluster Grignard reagents inaccessible for classical organometallic synthesis but provided no actual evidence of their formation and stabilization. 

The theoretical study by Khan et al. [13] on the stereochemistry of nucleophilic addition of organometallics to unsaturated substrates can also be applied to conjugated systems. Of the three major factors affecting the orientation of the nucleophile to the substrate (see Chapter 16), the ability of the substrate to discriminate between the nucleophilic and electrophilic character of the Grignard reagent is the one most susceptible to influence by conjugation with an adjacent 7r-system. They concluded that the accessible electrophilic site (the metal) is the source of the stereochemical preference for the electron-rich olefin face. 

Aitken, D. J., Beaufort, V., Chalard, P., Cladiere, J.-L., Dufour, M., Pereira, E., Thery, V. Theoretical and model studies on the chemoselectivity of a Grignard reagent s reaction with a combined aminonitrile-oxazolidine system. Tetrahedron 2002, 58, 5933-5940. 

A series of symmetrical aromatic 1,3-diols has been efficiently synthesized fl-om substituted aryl Grignard reagents and isopropenyl acetate in a one-step reaction that formed anti products as the major species (Scheme 8). Both experimental and theoretical studies suggested that the reaction involves the formation of a relatively stable intermediate containing a six-membered ring (17). 

Kulinkovich himself proposed that the dialkoxytitanacyclopropanes as the key intermediate in the Kulinkovich cyclopropanation. Extensive theoretical study on mechanism was published in 2001. Eisch also provided detailed exploration of the mechanism for the Kulinkovich reaction in 2003. In 2007, Kulinkovich proposed a modified ate complex mechanism for titanium-mediated cyclopropanation of carboxylic esters with Grignard reagents. 

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