Epoxy sulphones

The major product of the reaction between the 3)8-acetoxy-la,2a-epoxy-6j8-yl mesylate (216) and HCl-ether-MeOH was established as la,2/3-dihydroxy-cholesterol and not the epoxide (217) as had previously been reported. The epimeric 2-hydroxy-3-methylenecholestanes (219) were synthesized by reaction of the epoxy-sulphones (218) with Na/Hg in methanol. The 14a-hy-droxycholestanes (220), (221), and (222) have been synthesized and the key step in each case was the Se02 oxidation of the 6-oxo-A -compound. The key step in the synthesis of 3j8,5-dihydroxy-5/3-cholestan-19-ol (223) was the HOBr addition to the 19-formyloxy-A -compound (224) which gave the 5j8-hydroxy-... 

A simple one-pot synthesis of the bicyclobutanes (178 R = H, = R" = H or Me R = Me, R = H, R = Pr ) (> 50%) from (177) has been reported. Sequential treatment of (177) in THF at 0°C with one equivalent each of BuLi, methanesulphonyl chloride, and then BuLi again, to give (17 ), may be accomplished in 10 minutes. Terminal 7-epoxy-sulphones, on treatment with two equivalents of MeMgl, give c/s-3-phenylsulphonylcyclo-butanols thus (179) yields (180). This reaction contrasts with that of (179) with MeLi or with LiNPr 2, which gives derivatives of cyclopropyl-methanol. 

An extensive article on the importance of chalcone oxides in flavonoid chemistry contains 346 references. Other specialised reviews have appeared on the chemistry of juvenile hormones (up to 1974), epoxy-sulphones, and epoxyderivatives of dicyclopentadiene. ... 

The reduction of /Sy-epoxy-sulphones has been used as a new synthesis of a-methylene-carbinols. "" The epoxy-sulphone (153), prepared from 1-cyclo-hexenylmethanol, was reductively eliminated by Na(Hg) in THF-MeOH to methylenecyclohexanol (154). The same reduction/elimination procedure comprises part of that for a general synthetic sequence of allylic alcohols (156 R ,R, R" = H or Me, R = hexyl), via )3y-epoxy-sulphones (155), in 60—90% yields. "" Any group R" may be introduced by alkylation of (155 R" = H). 

The base-catalysed isomerization of /3-epoxy-sulphones (126) to y-hydroxy-ajS-unsaturated sulphones (127) was shown by kinetic data, an isotope effect, and stereochemistry to involve an intramolecular suprafacial 1 -> 3 hydrogen migration, with a carbanion-like transition state. " 4-Hydroxy-2-sulpholen, 3-hydroxy-4-chlorosulpholan, and 3,4-epoxysulpholan were found to react with thiolates to give mixtures of cis- and tran5-3-hydroxy-4-(alkylthio)sulpholans in a ratio of 2 3." ... 

The easily formed cp-chloro-cr-phenylsulphinyl cr-lithio-compounds (74) provide the starting point for syntheses of epoxy-sulphones (76 R = = H), enones... 

Methanolysis of the glycopeptides of antibiotic A 82846 gave 4-epi-vancosamine in the first isolation of this compound from a natural product. Treatment of epoxy-sulphones (37) and (38) with sodium azide afforded the azoaldehydes (39) and (40) respectively. Condensation of 2,3-Q-isopropylidene-D-... 

Acyclic y-epoxy-sulphones have been converted into cyclobutenones (Scheme 28)while cyclic /8-epoxy-sulphones have been used for the synthesis of a,/8-disubstituted cyclopentenones (Scheme 29). 

Rautenstrauch has shown that the cyclobutane ring system found in the monoterpenes fragranol and grandisol can be produced by intramolecular cyclization from an epoxy-sulphide of the type (43), and Corbel et al have demonstrated the use of epoxy-sulphones [viz. (44)] in the elaboration of cyclobutanols. 

Figure 10.7 Comparison of the damping peaks of tetraglycidyl methylene diamine and diamino diphenyl sulphone (TGMDA-DDS epoxy network) (O) and poly(bismaleimide) (BMI network) ( ).

The antiplasticization phenomenon is presumably common to all the polymers exhibiting a relatively strong (5 transition, well separated from the a transition. It has been observed for both linear (PVC, polycarbonate, poly-sulphones) and network polymers (amine-crosslinked epoxies). For the case of thermosets, the phenomenon may be a consequence of both internal (change of the network structure) and external (incorporation of miscible additives) modifications of the structure or the composition but it always seems to be a consequence of the plasticization, as shown in Fig. 11.7. 

POLY(BISPHENOL CARBONATE) -EPOXY RESINS CELLULOSE ACETATE - POLY(Bisphenol-A/Bisphenol sulphone)... 

Full details have been given28 of the previously reported29 synthesis of ( )-prephytoene alcohol (47) by a route involving condensation of the Qo sulphone (48) with the C20 ester (49). Lycopersene 1,2-epoxide [1,2-epoxy-... 

A group of reactions involving 16,17-epoxy-pregnane derivatives illustrates the facility of C(is) methyl migration to an electron deficient C(i ). The i6a,i7a-epoxypregnan-20-ones (13) react with acetic anhydride and toluene- -sulphonic acid [24], hydrogen fluoride [23], and other acidic reagents [23,26], to form i7a-acetyl-i7/5f-methyl-i8-nor-olefins (14) and (15). The preferred position of the double bond apparently... 

The previously observed backbone rearrangement of cholest-5-ene to cholest-13(17)-ene in acetic acid-toluene-p-sulphonic acid and the subsequent slow epi-merization at C-20 were shown by a deuterium incorporation study to involve a series of carbo-cation-olefin equilibria.101 The full account was reported for the BCl3-catalysed backbone rearrangement of 4,4-dimethyl-6,20-epoxy-5a-andro-stane.102 The oxetane (96) was reported103 to react with RCN-HBF4 to give the... 

Selective removal of bromine from 3/3,5,6/3-tribromo-5a-cholestane to give 3/3-bromocholest-5-ene was achieved by reaction with [T -C5H5Cr(N02)2]2. The reactions of 11/3-hydroxy-steroids with dialkylaminosulphur trifluorides depend on the substitution at C-9 and involve the formation of intermediate (11) (Scheme 1) (see ref. 232). Selective dehydration with FeCls adsorbed on silica gel allowed the conversion of 5a-cholestane-3/3,5-diol into cholesterol (80%) and 3i3-acetoxy-5a-cholestane-5,25-diol into 3/S-acetoxycholest-5-en-25-ol (72%). Other examples and additionally the hydrolysis of 5,6a-epoxy-5o -cholestan-3/3-ol to the 3/3,5a,6/8-triol (90%) were reported. Chromatographic alumina is reported to effect smooth elimination of sulphonic acids from the esters with less than normal rearrangement. Thus lanosteryl tosylate and cycloartenyl tosylate gave the respective A -compounds in yields of 90% and 45% respec-... 

The lability of 11-hydroxyolean-12-ene derivatives, observed during the course of this investigation, was employed in the conversion of dihydropriverogenin A (148) into the thermodynamically less stable priverogenin B (149). The triacetate of 18 -olean-3jS, 12/i, 13/ ,28-tetraol yielded the 13, 28-epoxy-derivative (150) on treatment with toluene-p-sulphonic acid. 

Super-hydride (LlBEt H) has been shown to be more effective than other reagents (e.g.. LAH) for reductive cleavage of epoxides and sulphonate esters. Thus methyl a-abequioslde (3) was obtained in 94 yield on reduction of the epoxy-sugar sulphonate (4), while... 

Cole, K.C. Hecher, J.J. Noel, D. (1991). A new approach to modeling the cure kinetics of epoxy amine thermosetting resins 2. Application to a typical system based onbis[4-(diglycidylamino)phenyl]methane and bis(2-aminophenyl) sulphone. Macromolecules, Vol.24, No.ll, (May 1991), pp. 3098-3110, ISSN 0024-9297. 

An extensive study on anticorrosion properties of PANI, PPy and PEDOT used as additives was reported in [88]. Results indicate that the protection against corrosion imparted by the formulations modified by the addition of poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulphonate), PANI-ES and, especially, PANI-EB is significantly higher than that of the unmodified epoxy paint. Thus, results evidence that some CP compositions can inhibit the steel corrosion and, therefore, small concentrations of these materials would be used to replace conventional inorganic corrosion inhibitors currently used in primer paints. In Table 10.6, some examples of the... 

A variety of poly/dihydric oils are used for the preparation of glyddyl ether-type epoxy resins. These include bisphenols, namely bisphenol-A (BPA), bisphenol-F (BPF), bisphenol-S (BPS) and bisphenol-H (BPH) and so on. Other aromatic diols and polyols such as phenolic resin, MF resins and hyperbranched polyol may also be used in the preparation of vegetable oil-based epoxy resins. Bisphenol-A (2,2-bis(4-hydroxyphenyl)propane) is one of the most widely used aromatic diols for the synthesis of epoxy resin. The resins are commonly used as lacquers for coated metal products such as food cans, bottle tops and water pipes. There are also reports on the use of bisphenol-S (BPS) (bis(4-hydroxyphenyl) sulphone), in the synthesis of epoxy resin. The advantages of resistance to deformation by heat and improvement of thermal stability were observed for such epoxy resins. The presence of sulphone group (BPS-based epoxy resin) in the epoxy resin exhibits better gel time than BPA-based epoxy. Another important diol, namely bis(4-hydroxydiphenyl)methane or bisphenol-F (BPF) is used for the synthesis of low viscosity epoxy resins. BPF generally comprises several isomers such as bis(2-hydroxylphenyl)methane (i.e. ortho-ortho isomer), bis(4-hydroxylphenyl)methane (i.e. para-para isomer) and... 

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