145025-01-0Relevant academic research and scientific papers
Mechanistic studies on the reactions of trimethylsilanide and trimethylstannylide ions with haloarenes in hexamethylphosphoramide
Postigo, Al,Vaillard, Santiago E.,Rossi, Roberto A.
, p. 108 - 115 (2002)
The large positive ρ values obtained from Me3M- ions reacting with appropriately-substituted chloroarenes (4.1+/-0.1, and 2.94+/-0.02 for M=Sn and Si respectively) can be accounted for the presence of a strong negative charge in the transition state of the substitution reaction. These ρ values for Me3Sn- and Me3Si- nucleophilic attack on ArX provide evidence for the overall larger selectivity of the former, compared with the more reactive, and less selective Me3Si- ions. When 1-allyloxy-2-halobenzenes (X=Cl, I) are allowed to react with Me3Sn- ions in HMPA, an ipso substitution product 6 is obtained, in addition to stannylated products on the allylic moiety. This reaction proceeds by a HME process, as opposed to the same reaction carried out in liquid ammonia, where (2,3-dihydro-benzofuran-3-ylmetyl)-trimetylstannane (4) is furnished in high yield through an SRN1 mechanism. Reaction of Me3Si- ions with 1-allyloxy-2-iodobenzene in HMPA, affords only the ipso-substituted product, namely 2-(allyloxyphenyl)-trimethylsilane (11), through the intermediacy of a hypervalent silicon species.
