Dimethyldioxirane, rearrangement using

Dinitrocubane (28) has been synthesized by Eaton and co-workers via two routes both starting from cubane-l,4-dicarboxylic acid (25). The first of these routes uses diphenylphos-phoryl azide in the presence of a base and tert-butyl alcohol to effect direct conversion of the carboxylic acid (25) to the tert-butylcarbamate (26). Hydrolysis of (26) with mineral acid, followed by direct oxidation of the diamine (27) with m-CPBA, yields 1,4-diiutrocubane (28). Initial attempts to convert cubane-l,4-dicarboxylic acid (25) to 1,4-diaminocubane (27) via a Curtins rearrangement of the corresponding diacylazide (29) were abandoned due to the extremely explosive nature of the latter. However, subsequent experiments showed that treatment of the acid chloride of cubane-l,4-dicarboxylic acid with trimethylsilyl azide allows the formation of the diisocyanate (30) without prior isolation of the dangerous diacylazide (29) from solution. Oxidation of the diisocyanate (30) to 1,4-dinitrocubane (28) was achieved with dimethyldioxirane in wet acetone. Dimethyldioxirane is also reported to oxidize both the diamine (27) and its hydrochloride salt to 1,4-dinitrocubane (28) in excellent yield. ... 

Direct oxidation of aromatics with m-CPBA in a two-phase system affords the most stable so-called K-region arene oxides in moderate yields.805 Careful control of pH is necessary to avoid acid-catalyzed rearrangement of the acid-sensitive product epoxides. The new powerful oxidants, dimethyldioxiranes,81,82 have also been used to convert arenes to arene oxides.806... 

Epoxidation of exocyclic enol lactones. Peracids, even under buffered conditions, are not useful for this epoxidation because of rearrangement and decomposition. Dimethyldioxirane effects epoxidation of y-methylene-y-butyrolactones (1) in 94-96% yield in 2-3.5 hours. It is also effective for epoxidation of endocyclic enol lactones such as 3. 

The dehydrogenation of 2 -hydroxychalcones and flavanones to flavones, of l-(2-hydroxyaryl)alk-2-en-l-ones and chroman-4-ones to chromones and of thiochroman-4-ones to thiochromones can be accomplished using iodine in hot DMSO <97HCM223>. E-3-Styrylchromones result from the oxidative rearrangement of 5-aryl-l-(2-hydroxyphenyl)penta-2,4-dien-l-ones with thallium(lll) nitrate <97LA2065>. Dimethyldioxirane converts flavanones into flavones by way of the 2-hydroxyflavanone. This approach enables flavans to be converted to a variety of flavonoids <97TL4651>. 

The VAE has also been used to generate nitrosoalkenes from a-chloro ketoximes and to accelerate Claisen rearrangements of appropriately substituted substrates. An interesting example of the remote effect on reactivity was found in the epoxidation of 4-deoxypentenosides (4-DPs) by dimethyldioxirane (DMDO) where competing directing effects can be imposed by the anomeric and allylic substituents. ... 

An in situ method for epoxidations with dimethyldioxirane using buffered aqueous acetone solutions of Oxone has been widely applied. The epoxidation of 1-dodecene is particularly impressive in view of the difficulty generally encountered in the epoxidation of relatively unreactive terminal alkenes (eq 7). A biphasic procedure using benzene as a cosolvent and a phase-transfer agent was utilized in this case. Equally remarkable is the epoxidation of the methylenecyclopropane derivatives indicated in eq 8, given the propensity of the products to rearrange to the... 

---