I have seen quite a literature for the synthesis of grignard reagent for creating C-C bong having EWG directly attached to the molecule using Turo grignard reagnet (Isopropylmagnesium chloride lithium chloride complex solution) via exchange reaction at low temperature (-40, -10 etc) to avoid side reaction (Wurtz coupling reaction etc), or molecule having sensitive groups like nitrile,
Can we use this reagent for the synthesis of grignard reagent of molecule without EWG directly attached to molecule? and this synthesized grignard reagent can further be used for the reaction with carbon disulphide (synthesis of dithiobenzoate compund)?
any useful suggestions ?
Yes, metallation with TurboGrignard (and related Knochel-Hauser-Base) proceed also in presence of electro-donating groups: 1) phenol salts http://pubs.rsc.org/en/Content/ArticleLanding/2004/CC/b409664a#!divAbstract ; 2) http://www.sigmaaldrich.com/chemistry/chemical-synthesis/technology-spotlights/chemetall.html
Presence of EWG and halogens allows to direct and stabilize some selected position in molecule but is not strong demand in presense in reacting ring; it is sufficient to have C-H acidity in selected position. Old "receipts" as tert-BuOK+BuLi, tert-BuLi or addition of TMEDA to BuLi can help in metallation for critical cases.
Metallated positions are subject to electrophilic attack - including CS2. As reported, dithiobenzoic acids are not suitable to purification. IMHO, addition of Me3SiCl to reaction will produce distillable silyl esters. Deprotection of silyl from sulfur is very simple by reaction with water ( especially with F- catalysis)
Nadeem, if you could let me know which substrate you are planning to use, I think I would be able to give you more precise advice concerning the conditions - I was among those who have developed these reagents. it depends a lot on whether you take bromide or iodide and is your substrate a heterocycle or a usual arene.
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