Gallium complexes sulfides

These complexes are the first examples of multifunctional catalysts and demonstrate impressively the opportunities that can reside with the as yet hardly investigated bimetallic catalysis. The concept described here is not limited to lanthanides but has been further extended to main group metals such as gallium [31] or aluminum [32]. In addition, this work should be an incentive for the investigation of other metal-binaphthyl complexes to find out whether polynuclear species play a role in catalytic processes there as well. For example, the preparation of ti-tanium-BINOL complexes takes place in the presence of alkali metals [molecular sieve ( )]. A leading contribution in this direction has been made by Kaufmann et al, as early as 1990 [33], It was proven that the reaction of (5)-la with monobromoborane dimethyl sulfide leads exclusively to a binuclear, propeller-like borate compound. This compound was found to catalyze the Diels-Alder reaction of cyclopentadiene and methacrolein with excellent exo-stereoselectivity and enantioselectivity in accordance with the empirical rule for carbonyl compounds which has been presented earlier. 

Gallium (II) complexes, 127 halides, 128 selenides, 128 sulfides, 128 tellurides, 128... 

The formation of P-bromohydrins and p thioalcohols from epoxides has also been reported. For example, Shibasaki has shown that the heterobimetalhc gallium lithium BINOL complex (12.138) is a good catalyst for nucleophilic ringopening of epoxides, including the use of thiols. Cyclohexene epoxide (12.116) is converted into the sulfide (12.141) with very good enantioselectivity. Indium complexes of bipyridine (12.126) are very active catalysts in the thiolysis of meso-epoxides providing between 92 and 96% ee in the reaction of ds-stilbene oxides with a range of aromatic and aliphatic sulfides. ... 

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