Aluminum selenolate

Like the three-coordinate aluminum and gallium alkoxides, the corresponding thiolates, selenolates, and tellurolates require very bulky substituents at the chalcogen atom to ensure a low metal coordination number. In addition, the steric requirements associated with the preservation of the low coordination number at the metal are increased by the longer M—S and M—Se bond lengths. The ten examples of low-coordinate,... 

Metal-Sulfur, -Selenium, and -Tellurium Bond Lengths, M—E—C Angles, and Torsion Angles for Three-Coordinate Aluminum, Gallium, and Indium Thiolates, Selenolates and Tellurolates", and Related Compounds... 

Ring opening of larger cyclic ethers such as tetrahydrofuran does not normally proceed with selenolates of type 77 generated from diselenides and sodium borohydride in alcohols. If diselenides are reduced with lithium aluminum hydride in tetrahydrofuran,171 or with sodium borohydride in the presence of aluminum trichloride,172 ring-opened products 89 are obtained (Scheme 20). 

Selenolates prepared from diphenyl or dimethyl diselenide by reduction with NaBH4 smoothly transform various benzylic alcohols 24 into the corresponding selenides 25 in the presence of aluminum chloride (Scheme 30 a) [41]. AICI3 is considered to activate the alcohol substrate by coordinating to the oxygen. Similar transformations are possible by the reaction of alcohols with phenyl selenocyanate in the presence of tributyl phosphine [52]. When the selenolate is reacted with aromatic aldehydes or ketones 26 in the presence of AICI3, the corresponding benzylic selenides 27 are obtained in moderate yields (Scheme 30b) [41]. 

The addition of alcohols to N-alkylidene selenoamides generated in situ leads to N-alkoxyalkyl selenoamides [84]. The substitution reaction of alkoxy groups of selenoesters [RC(Se)OR ] with aluminum thiolates or selenolates proceeds smoothly to give the corresponding esters [RC(Se)SR, RC(Se)SeR ] [7a, 85], whereas the addition of thiols to selenoaldehydes takes place at the selenium atom to afford selenenesulfides (RCH2SeSR ) [86]. 

Selenol esters are useful as active acyl equivalents, particularly with regard to macrocycle formation. Equation (21) outlines the conversion of esters to selenol esters via aluminum reagent (48). ... 

Selenoacetals are readOy available compounds which have been prepared (i) by selenoacetalization of carbonyl compounds with selenols - in acidic media, with tris seleno)boranes > in neutral or acidic media or with trimethylsilyl selenides and aluminum trichloride (Schemes 69 and... 

The self-assembly of organoaluminum selenolates and tellurolates, by dative bonding, into supermolecules is remarkable in view of the relatively weak donor properties of selenium and tellurium (soft bases) towards aluminum (hard add). 

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