70398-91-3Relevant academic research and scientific papers
SELECTIVE DEALKYLATIONS OF ARYL ALKYL ETHERS AND THIOETHERS BY SODIUM IN HMPA
Testaferri, L.,Tiecco, M.,Tingoli, M.,Chianelli, D.,Montanucci, M.
, p. 3687 - 3692 (2007/10/02)
The reaction of sodium with bis- and tris(alkoxy)benzenes in HMPA gives selectively the products of monodealkylation.The reaction proceeds through a dianion which fragments into an alkyl and an aryloxy anion.The positional selectivity of this fragmentation is governed by the structure of both the alkyl and aryloxy groups.With bis- and tris(alkoxy)benzenes which for symmetry reasons can afford aryloxy anions having the same basicity, the dealkylation involves exlusively the less substituted alkyl group.On the contrary, in the asymmetric terms, the positional selectivity of the dealkylation process is governed by the basicity of the aryloxy anion.On the basis of these concepts several efficient and synthetically useful reactions have been developed.In most cases the selectivity obtained in the present reactions in different from that observed with other previously developed methods which use sodium methoxide or sodium alkenethiolates in HMPA.It is shown that the appropriate choice of the reagent allows selective dealkylation of the desired alkoxy group of a poly(alkoxy)benzene.The reaction of sodium with bis(alkylthio)benzenes in HMPA gives the bis(mercapto)benzenes.If the reduction is carried out with a solution of sodium in HMPA, the reaction gives instead the products of monodealkylation.This however is not selective.It is suggested that in the case of thioethers the dealkylation products originate from the fragmentation of the radical anions.
Reactions of Polychlorobenzenes with Alkanethiol Anions in HMPA. A Simple, High-Yield Synthesis of Poly(alkylthio)benzenes
Testaferri, Lorenzo,Tingoli, Marco,Tiecco, Marcello
, p. 4376 - 4380 (2007/10/02)
Reactions of the isomeric trichlorobenzenes and tetrachlorobenzenes and of pentachloro- and hexachlorobenzene with an excess of the sodium salt of the isopropanethiol, in HMPA, afforded the products of complete displacement of all the chlorine atoms present in the molecule.Similar substitutions were also obtained with EtSNa.The reactions with MeSNa were in some cases complicated by the competitive nucleophilic attack at the methyl group of the initially formed aryl methyl thioethers which are thus demethylated to afford thiophenols.
