Cyclic polythioether

A useful route toward heteronines is an application of 1,3-dielectrophiles when they react with O- and S-nucleophiles. The chiral (R)-l,l -bi-2-naphthol 152 was reacted with 3-chloro-2-(chloromethyl)prop-l-ene to afford dioxonine 153 (Scheme 28, Section 14.10.6.1) <1998JA5943, 1997TA2921>. A novel procedure for the preparation of cyclic polythioethers by the reaction of dithioiminium salt with 1,3-dihalopropane using phase-transfer catalyst has been reported (Equation 28) <2003PS1295>. This approach avoided the use of thiols, which are not only hard to handle, but also prone to oxidation. 

The cyclic polythioether complex [W(CO)4L] (L = 2,5,8,ll-tetrathia[12](2,5)thiophenophane was prepared by UV irradiation of [W(CO)6] in the presence of the ligand in thf. Variable-temperature H NMR studies showed that this species was fluxional, and the derived molecular structure indicated k -L-S S coordination (17). The thioether-bridged complexes [ W(CO)4)2T] (18), where L is the hexakis(alkylsulfanylmethyl)benzene, C6(CH2SR)6 (R = C5H11, Pr ) were obtained by reaction of [W(CO)4(NCMe)2] with the appropriate thioether. Reaction of [W(CO)4(tmpa)] (tmpa = V,iV,iV, iV -tetramethyl-l,3-propanediamine) with 1,5-diselenacyclooctane ([8]aneSe2) gave the cis-disubstituted produce [W(CO)4 [8]aneSe2 ]. 

This catalysis involves (l,2-ethanedithiolato)tungsten intermediate, which can be trapped by the addition of dimethyl acetylenedicarboxylate (DMAD). Interestingly, in the presence of DMAD, the formation of cyclic polydisulfides is greatly suppressed, and the cyclic polythioethers (thiacrowns) are mainly formed (Scheme 3.72). 

The chemical and physical properties of the polymers obtained by these alternate methods are identical, except insofar as they are affected by differences in molecular weight. In order to avoid the confusion which would result if classification of the products were to be based on the method of synthesis actually employed in each case, it has been proposed that the substance be referred to as a condensation polymer in such instances, irrespective of whether a condensation or an addition polymerization process was used in its preparation. The cyclic compound is after all a condensation product of one or more bifunctional compounds, and in this sense the linear polymer obtained from the cyclic intermediate can be regarded as the polymeric derivative of the bifunctional monomer(s). Furthermore, each of the polymers listed in Table III may be degraded to bifunctional monomers differing in composition from the structural unit, although such degradation of polyethylene oxide and the polythioether may be difficult. Apart from the demands of any particular definition, it is clearly desirable to include all of these substances among the condensation... 

The systems with which we have been working involve aquo-copper(II) ion reacting with a series of cyclic and open-chain polythioether ligands, each with four or more donor atoms. We first noticed that, as one increases the concentration of "inert" anions, such as CIO, BF, and CF SO, the stability of the... 

First, the sulfur atom from a thiirane is added to one of the carbon atoms of the thiirane ligand of the complex, with formation of a zwitterionic intermediate. The zwitterionic intermediate undergoes elimination of ethylene to yield a reactive alkene disulfide tungsten complex. The dithietane ligands from two or more molecules, then combine to form the cyclic polysulfides. If the macrocyclization of thiirane catalyzed by W(CO)s(SC2H4) is performed in the presence of DMAD, small quantities of polythioether macrocycles 156 and 157 are formed <1997OM1430>. 

Electrochemical studies of these polymers showed a reversible reduction couple.257 The cyclic voltammogram of an organometallic polythioether is shown in Figure 2.4 where the Em=- 0.85 V. 

A review of recent developments in synthetic organic sulphur chemistry included much valuable material pertinent to cyclic sulphur compounds, and another review covered photocycloaddition reactions of thiocarbonyl compounds with olefins to give 1,4-dithians and cycloadditions with dienes to give thian derivatives. Macrocyclic polythioethers and their complexes have been reviewed, and in other articles the conformational aspects of multisulphur heterocycles, sulphur-containing [2,2]metacyclophanes, and other cyclic sulphur compounds have been discussed. Other reviews mention configurational aspects of cyclic sulphur compounds. ... 

A novel one-pot synthesis of sulfur-containing polymers including poly(monosulfide)s (polythioethers), poly(disulfide)s, polythioesters, and poly-thiourethanes from a five-membered cyclic dithiocarbonate (5-phenoxjunethyl-l,3-oxathiolane-2-thione) and diamines has been examined. Polythioethers with Mn = 2600-17,700 were obtained by condensation of in situ forming dithiol with o ,a -dibromo-p-xylene [623-24-5] (25). A synthesis by using a bifimctional five-membered cyclic dicarbonate and benzylamine [100-46-9] has also been reported (26). 

Contrary to the extensive studies on the coordination properties of polythioether macrocycles (35-42), little information is available about cyclic... 

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