Vinyl epoxides substitution reactions

The various allylic substitution reactions are illustrated in a synthesis of Tipranavir (11), an HIV protease inhibitor. A palladium-catalyzed opening of a vinyl epoxide set the quaternary stereogenic center (Scheme 22.23). A molybdenum-catalyzed allylic nuclophilic displacement was used to access the benzylioc stereogenic center (Scheme 22.24).153... 

Vinyl epoxides can be cross-coupled with vinylstannanes <2001JOC589>. This reaction proceeds through an (if-allyOpalladium complex (Equation 57) <2001JOC589>. Similar reactivity can be observed using bismuth reagents (Equation 58) <2001SC2365>. Vinyl oxiranes react with substituted allenes to form functionalized allyl alcohols <2004JOC4686>. 

On treatment with a palladium(O) catalyst, vinyl epoxides undergo facile unimolecular rearrangement to give dienols or enones depending on the substitution pattern of the substrate. In the presence of an active methylene compound in the reaction system, however, a single alkylation product is formed. Cyclic and acyclic vinyl epoxides participate equally well. The reaction proceeds with clean alkylation from the same face as the oxygen of the epoxide, and proceeds with allyl inversion (Scheme 22). ... 

Palladium-catalyzed nucleophilic substitution reactions of allylic substrates have become useful in organic synthesis. As allylic substrates, allyl alcohols, halides, carboxylates, phosphates or vinyl epoxides can be utilized. 

The biphasic double carbonylation of phenyloxiranes under PT conditions affords 4,5-dihydro-4-phenylfuran-2,3-diones [162]. A similar reaction involving 2-phenylthiirane gives the ) -mercapto-substituted acid [163]. The PTC reaction of vinyl epoxides with CO and Mel in the presence of catalytic amounts of Co2(CO)h and TDA-1 affords /ff-hydroxy acids [164]. 

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