82823-89-0Relevant academic research and scientific papers
Reaction of Trimethyl- and Triphenylstannate, (CH3)3Sn(-) and Ph3Sn(-), with Optically Active 2-Octyl Bromide, Chloride, and Tosylate
Filippo, Joseph San,Silbermann, Joseph
, p. 2831 - 2836 (1982)
The reaction of lithium, sodium, and potassium trimethylstannate, (CH3)3SnLi, -Na, and -K, and triphenylstannate, Ph3SnLi, -Na, and -K, with optically active 2-octyl tosylate, chloride, and bromide is reported.Alkylation of (CH3)3SnM with 2-octyl tosylate proceeds with complete inversion at carbon.The corresponding reactions with 2-octyl chloride and especially 2-octyl bromide show considerably greater variations in reaction stereoselectivity.These variations depend on a variety of reaction parameters, including the order of reagent addition, i.e., normal vs. inverse addition of reagents, reaction temperature, solvent, gegenion, concentration, and additives.Thus, for example, at 0 deg C the normal addition reaction of 2-octyl chloride with (CH3)3SnM in THF proceeds with 100percent inversion of configuration, while the equivalent reactions with 2-octyl bromide proceed with 34percent (M = Na), 33percent (M = K), and 53percent (M = Li) net inversion.The latter reactions are more stereoselective when carried out at lower temperatures: at -70 deg C the corresponding values are 62percent (M = Na) and 83percent (M = Li) net inversion.Stereoselectivity in these reactions is dramatically influenced by the order of reagent addition.Thus, under inverse-addition conditions, for example, the reaction of (CH3)3SnM with 2-octyl bromide in THF at 0 deg C occurs with high stereoselectivity (97percent and 98percent net inversion, respectively, for M = Li and Na) and with minor adjustment of other parameters can be made to occur stereospecifically.Both the normal and indirect addition of Ph3SnLi and -Na to 2-octyl bromide occur with complete inversion of configuration at carbon.A comparison of the reactivity of (CH3)3SnM and Ph3SnM reveals that the latter is significantly less reactive than the former; triphenylstannate, however, is the more stereoselective reagent, its reaction with optically active 2-bromooctane being essentially stereospecific, irrespective of the order of reagent addition.The results of this study and those from earlier investigations involving the cis- and trans-4-tert-butylcyclohexyl and cyclopropylcarbinyl systems are compared and discussed as well as the reliability of recently reported trapping experiments for discerning between the SN2 and free radical components of such reactions.
Reaction of (Triphenylmethyl)-, (Triphenylsilyl)-, (Triphenylgermyl)-, and (Triphenylstannyl)lithlum with Optically Active 2-Octyl Tosylate, Chloride, and Bromide
Lee, Kang-Wook
, p. 1496 - 1501 (2008/10/08)
The reaction of (triphenylmethyl)-, (triphenylsilyl)-, (triphenylgermyl)-, and (triphenylstannyl)lithium
