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Wittig Reaction: Domino Olefination and Stereoselectivity DFT Study. Synthesis of the Miharamycins’ Bicyclic Sugar Moiety

2015; American Chemical Society; Volume: 17; Issue: 22 Linguagem: Inglês

10.1021/acs.orglett.5b02849

1523-7060

Vasco Cachatra, A. Filipa Almeida, João Sardinha, Susana D. Lucas, Ana Isabel Gomes, Pedro D. Vaz, M. Helena Florêncio, Rafael Nunes, Diogo Vila‐Viçosa, Maria José Calhorda, Amélia P. Rauter,

Click Chemistry and Applications

2-O-Acyl protected-d-ribo-3-uloses reacted with [(ethoxycarbonyl)methylene]triphenylphosphorane in acetonitrile to afford regio- and stereoselectively 2-(Z)-alkenes in 10–60 min under microwave irradiation. This domino reaction is proposed to proceed via tautomerization of 3-ulose to enol, acyl migration, tautomerization to the 3-O-acyl-2-ulose, and Wittig reaction. Alternatively, in chloroform, regioselective 3-olefination of 2-O-pivaloyl-3-uloses gave (E)-alkenes, key precursors for the miharamycins' bicyclic sugar moiety.