151340-89-5Relevant articles and documents
Silanol Reactivity: Evaluation of Silanolate as a Metalation-Directing Group
Sieburth, Scott McN.,Fensterbank, Louis
, p. 6314 - 6318 (1993)
Alkali metal salts of dimethylarylsilanol and di-tert-butylphenylsilanol were treated with organometallic reagents to determine the viability of silanolates as ortho-metalation-directing groups.When dimethylphenylsilanol was treated with an excess of n-butyllithium, metalation was not observed.Heating these reactions led to substitution of the methyl and phenyl groups on silicon by n-butyl groups.When a m-methoxy group was present, metalation of the aromatic ring was observed between the two substituents.The more hindered di-tert-butylphenylsilanol was inert to excess n-butyllithium, but treatment of the potassium salt of this silanol with n-butyllithium results in metalation largely at the meta and para positions, with only traces of ortho products.Calculated deprotonation enthalpies of arylsilanes using AM1 can explain some of the observed acidities from this study as well as observations made in a related study of arylsilane metalation by Schlosser et al.
Cross-coupling reactions of aromatic and heteroaromatic silanolates with aromatic and heteroaromatic halides
Denmark, Scott E.,Smith, Russell C.,Chang, Wen-Tau T.,Muhuhi, Joseck M.
scheme or table, p. 3104 - 3118 (2009/08/07)
The alkali-metal salts (potassium and sodium) of a large number of aryl- and heteroarylsilanols undergo efficient cross-coupling with a wide range of aromatic bromides and chlorides under mild conditions to form polysubstituted biaryls. The critical feature for the success of these coupling reactions and their considerable scope is the use of bis(tri-tert-butylphosphine)palladium. Under the optimized conditions, electron-rich, electron-poor, and sterically hindered arylsilanolates afford cross-coupling products in good yields. Many functional groups are compatible with the coupling conditions such as esters, ketones, acetals, ethers, silyl ethers, and dimethylamino groups. Two particularly challenging substrates, (2-benzofuranyl)dimethylsilanolate and (2,6-dichlorophenyl)dimethylsilanolate prepared as their sodium salts showed excellent activity in the coupling reactions, in the former case also with aromatic chlorides. General methods for the efficient synthesis of a wide range of aromatic silanols are also described.
