Scope of the directed dihydroxylation: application to cyclic homoallylic alcohols and trihaloacetamides
作者:Timothy J. Donohoe、Lee Mitchell、Michael J. Waring、Madeleine Helliwell、Andrew Bell、Nicholas J. Newcombe
DOI:10.1039/b303081d
日期:——
The synthesis and directed dihydroxylation of a range of cyclic alkenes was investigated. Both homoallylic alcohols and homoallylic trihaloacetamides were found to be efficient directing groups, giving rise to good to excellent levels of remote asymmetric induction with OsO4–TMEDA. Interestingly, in all cases examined, trifluoroacetamides were found to be superior to trichloroacetamides as directing groups and an argument is presented which rationalises this observation.
A general synthesis of 5-unsubstitutedbenzylpyrrole-2-carboxylates was developed based on the reaction of β-nitroacetates with benzylisocyanoacetate. The advantage of this route over other pyrrole syntheses was the regiochemical control of the substitution pattern on the pyrrole ring.
Free radical addition reactions of allylic sulfones to alkenes
作者:Iain W. Harvey、Eifion D. Phillips、Gordon H. Whitham
DOI:10.1016/s0040-4020(97)00306-2
日期:1997.5
Intermolecular radicalreactionsinvolving formal addition of the sulfonyl and allyl fragments of an allylic sulfone across the double bond of an alkene are described. Reactions are most successful when the allylic sulfone has an electron withdrawing group at the 2-position. Only monosubstituted alkenes give useful yields of adducts, though both electron withdrawing and electron donating substituents
Construction of Multisubstituted Tetrahydropyrans by a Domino Oxa-Michael/Tsuji–Trost Reaction
作者:Liang Wang、Dirk Menche
DOI:10.1021/jo302102x
日期:2012.12.7
Biologically significant tetrahydropyrans (THP) were synthesized by a Tandemoxa-Michael/Tsuji–Trostreaction. Different Michael acceptors were investigated, and optimal results in terms of diastereoselectivities and yields were obtained with nitro olefins. The influence of the reaction parameters, substrate patterns, and type of metal counterions on the yield and stereochemical outcome of this process
β-Sulfonylnitroolefins as very reactive alkyne-equivalents in Diels-Alder reactions
作者:Noboru Ono、Akio Kamimura、Aritsune Kaji
DOI:10.1016/s0040-4039(00)84323-3
日期:1986.1
Very reactive dienophiles, β-sulfonylnitroolefins, are prepared starting from β-nitro alcohols. The high activation due to the nitro and the sulfonyl groups promotes the Diels-Alder reaction to various dienes under mild conditions. Reductive elimination of the adduct with Bu3SnH gives cyclic 1,4-dienes.