Phenyloxiranes thermal reactions

The Rli2(OAc)4-catalysed reactions of ethyl diazoacetate with substituted benzalde-hydes yielded 1,3-dioxolanes via an initially formed carbonyl yhde. Catalyst-dependent diastereo-control was observed only when /rnitrobcnzaldchydc was used as catalyst.104 The intramolecular cycloaddition of carbonyl yhde dipoles with tethered alkenyl 71-bonds is greatly enhanced by placing an sp2 centre on the tethered side-chain.105 The thermal reaction of 3-phenyloxirane-2,2-carbonitrile and 2-phenyl-3-thia-l-azaspiro-[4,4]non-l-ene-4-thione yields cis- and /raw.v-cycloadducts via a regioselective 1,3-dipolar cycloaddition of an intermediate carbonyl yhde.106... 

Thermal and Photochemical Reactions of Oxirans. - Isotopic labelling has been used to prove that the thermal rearrangement of phenyloxiran proceeds via a 1,2-shift of hydrogen, and not phenyl migration (Scheme 13). The epoxide (202), labelled with at C-2, gives entirely C(2)-labelled phenyl-ethanol (203) and 3,3- H2-labelled (202) gives (203) with at both C-1 and C-2. The method does not, however, distinguish between the transfer of H and of H. ... 

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See also in sourсe #XX -- [ ]

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