Tetraepoxide

The tandem oxacydization of a triepoxide was also explored. On treatment with BF3 Et20, the famesol-derived triepoxide 84, with a tert-butylcarbonate as the nucleophilic terminating functional group, afforded the tricyclic bis-oxepane 85 as the major product (52%, Scheme 8.21). The tetraepoxide derived from geranylger-aniol was similarly converted into the corresponding tetracyclic structure [39a]. 

Figure 14.4 Chemical structures of two common epoxy chain extenders for PET (a) a diepoxide, e.g. Shell Epon 828, based on bisphenol A diglycidyl ether (b) a tetraepoxide, e.g. Ciba MY721, based on tetraglycidyl diaminodiphenyl methane (TGDDM)...

Similarly, indenes undergo dye-sensitized photooxygenation at — 78°C in acetone to yield the usual oxygenated products, namely 2,3 7,9-diepoxy-6,9-peroxy-A4,5-hexahydroindenes (93). These compounds also undergo thermal rearrangement to form indene tetraepoxides (benzene oxides) (94) and are converted to 2,3 4,9 7,8-triepoxy-A5-6-hexahydroindenes (95) on treatment with trimethyl phosphite.49... 

The diazonide 131 obtainable from furanophene (132) with singlet oxygen is isomerized to the tetraepoxide 133 when photolyzed in methylene chloride.62... 

The Shi epoxidation has found several applications in total synthesis [15]. Particularly attractive are examples in which it has been used to establish the stereochemistry of polyepoxides which can undergo cascade cyclizations to polyether products, mimicking possible biosynthetic pathways. An example is the construction of the tetahydrofuran rings of the natural product glabrescol via highly stereoselective formation of the tetraepoxide 10 from the polyene 9 (Scheme 12.6) [22]. 

As in the cyanate/epoxide compositions, polysulfone is used as an additive in cyanate/epoxide/maleimide systems. As an example, a composition for carbon-fiber composites should be mentioned. It contains BPA/DC-BMI prepolymer, epoxide resin and polyethersulfone [111-113] Zn acetate and dicumyl peroxide are added. Polyethersulfone powder was added to the three-component system with 4,4 -diamino-diphenylmethane-based tetraepoxide as one of the epoxy resins used [114]. 

Curci et a/, have reported a nice example of a highly stereospecific dioxirane-mediated epoxidation of vitamin D2 into the corresponding (all-i )-tetraepoxide 69 <1996JA11089>. 

Moreover, in the same work, the 0-labeling experiment confirmed chiral dioxiranes to be the intermediates in chiral ketone-catalyzed epoxidation reactions. Murray et al. reported the synthesis and structural characterization of cyclooctatetraene tetraepoxides 90 and 91 through the oxidation of cyclooctatetraene with excess of DMDO lb... 

Tong RB, Boone MA, MeDraiald FE (2009) Stereo- and Regioselective Synthesis of Squa-lene Tetraepoxide. J Oig Chem 74 8407... 

The synthesis of the tetraepoxide (135) in high yield (80%) by heating a mixture of [2,2](2,5)furanophane (133) and 9,10-diphenylanthraceneperoxide (134) provides one example of the value of the latter reagent as a convenient source of singlet oxygen. In addition to the high yields of product obtained,... 

Based on the results obtained by Smolinski and Halaza [39], Boutevin et al. [29] reported the synthesis of fluorine-containing tetraepoxide with the chemical structure shown in Scheme 4. 

The first step reaction example involves the preparation of water-based epoxy resins via ring-opening polymerizations of different epoxides with various diamines, dithiols or diols residing in the miniemulsion droplets at 60°C [75]. The basic requirement for successful miniemulsion polymerization is that both reactive components exhibit relatively low solubility in the continuous aqueous phase. The diepoxide Epikote E828, triepoxide Decanol EX-314, and tetraepoxide EX-411 are potential candidates for this purpose. Furthermore, incorporation of conventional costabilizers such as hexadecane into the... 

The preceding tetraepoxide is not yet a natural product, but (+)-10(R),ll(R)-epoxysqualene was isolated from Laurencia okamurai (Kigoshi et al., 1986). The presence of this epoxide is surprising to the extent that it is the enantiomer of 10(S)ll(S)-epoxysqualene identified in the Chlorophyceae Caulerpa prolijera (Chapter 12). 

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