Reactions of dilithiobutadienes with monochlorosilanes: Observation of facile loss of organic groups from silicon

Reductive Lithiation and Multilithiated Compounds in Synthesis

“…The intermediate organodimetal was quenched with different electrophiles, leading to the recovery of a series of 2,2 ′ -disubstituted biphenyls, 35, in satisfactory to good yields. Formation of silafluorene, 36, is in agreement with a previous literature report for the reaction of 34, generated by a different procedure, with the same chlorosilane (Scheme 12.10) [31].…”

Computational Studies on the Reaction from Silyl 1,4‐Dilithio 1,3‐butadiene to Lithio Silole

“…In the experimental work, 16 Xi and coworkers reported that 2 was not formed, and when the reaction was carried out without hexamethyl-phosphoramide (HMPA), 5 or related isomers could not be detected. 28,29 On the other hand, this has been in disagreement with some related studies conducted without HMPA. For example, 7 was produced from 6 in 88% yield, as shown in Scheme 5.…”

“…Nevertheless, the isomerization mechanism for 1,1‐dimetalloalkenes is unclear at present, because isomerization could occur via many different mechanisms. Therefore, it is essential to determine if the first step in path (b) is a plausible process. In the experimental work, Xi and coworkers reported that 2 was not formed, and when the reaction was carried out without hexamethyl‐phosphoramide (HMPA), 5 or related isomers could not be detected . On the other hand, this has been in disagreement with some related studies conducted without HMPA.…”

Reaction of Dilithio Reagents with PhSiH3: Formation of Siloles and 3-Silacyclopentenes

“…Thus, the intermolecular substitution process could not proceed smoothly due to the inefficient substitution of the hydride ion of trisubstituted silanes. 14 Since both the solubility of the generated LiH and the reactivity of Si−H bonds will become enormously greater in more polar solvents, 15 we then turned to investigate the reaction of dilithio reagents with PhSiH 3 in THF. Although all other dilithio reagents afforded a mixture of products, the 1,4-bis(silyl)-2,3-diphenyl dilithio reagents 1g (Si = SiMe 3 ) and 1g′ (Si = Si t BuMe 2 ) reacted with PhSiH 3 relatively cleanly, affording 3-silacyclopentenes 3a and 3b with perfect selectivity in moderate yields, respectively (Scheme 3).…”