83500-75-8Relevant academic research and scientific papers
Evidence for intermolecular interaction between sulfonium and sulfide sulfur atoms and its application to synthesis of cyclic bis(disulfide) dimer
Kobayashi,Koyama,Kono,Namatame,Nakamura,Furukawa
, p. 2085 - 2090 (2007/10/03)
On the basis of the remote Pummerer reaction of p-bis(alkylthio)-aromatic S-oxide, the intermolecular interaction between the sulfonium and sulfide sulfur atoms is described. (1) In marked contrast to the Pummerer reaction of 1b-d3 with (CF3CO)2O (J. Org. Chem. 1999, 64, 3190-3195), the reaction of 3,3′,5,5′-tetramesityl-4-(trideuteriomethylsulfinyl)-4′- (methylthio)biphenyl (1a-d3) as a sterically hindered analogue of 1b gave only 2a-d2. (2) Both reactions of the two unsymmetrical regioisomers of 1-(ethylthio)-4-(methylthio)benzene S-oxide (5a and 5b) with (CF3CO)2O afforded a mixture of the mono-Pummerer products 6a and 6b, the bis-Pummerer product 7, and the bissulfide 8 in a similar ratio. The quenching at the initial stage of both reactions produced 5a, 5b, 8, and the bis-sulfoxide 10 in a similar ratio. These results indicate the equilibrium in the intermolecular interaction between the sulfur atoms. (3) The reaction of the p-bis(benzylthio)aromatic S-oxide 16 with (CF3SO2)2O gave the cyclic bis(disulfide) dimer 17 for the diphenyl sulfide and diphenylmethane spacers or the cyclic tetrakis(disulfide) tetramer 19 for the benzene and biphenyl spacers via the debenzylation of an intermolecular dithia dication. The cyclic bis(dithia dication) dimer A resulting from the intermolecular interaction between the sulfonium and sulfide sulfur atoms is proposed as an intermediate throughout the present reactions.
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.
