Micha el (A d d i + o n (–(Elimi n a + o nReac+on s (o f (Chiral(Enolat es(wi t hEthyl(3‐ h a l o p ro p en o a t esOrganic(Le+ers,(2008,(10,(65Jaume(V i l arrasa,(Alex( Gomez,(Anna(Costa,(Jorge(EstebanUniversit y ( of(Barcelona, ( SpainJosh(OsbournChem(2320(Journal(ClubMarch(24,(2008•The(reac+on(occurs(with(full(reten+on(of(the(ini+al(E(or(Z (doublebond(configura+on•Evans(oxazolidinones(as(well(as(the(authors(own(chiral(auxiliarieswere(used(in(the(reac+ons.A(common(feature(of(many(macrolide(an+bio+cs(is(a(dienoatemoiety(which(can(be(accessed(via(this(protocol.Evans:(JOC(1991,(56,(5750Michael(addi+on(of(+taniumenolates(to(ac+vated(double(bondsMany(ReferencesReview:(Maruoka:(ACIE,(2007,(46,(4222Conversion(of(a(trisubs+tuted(enolate(tocompounds(with(quaternary(carbons(inthe(presence(of(a(chiral(phase‐transfercatalystsVilarrasa’s(WorkAddi+on(of(a(chiral(enolate(to(3‐halopropenoates.These(results(are(not(useable,(however(they(suggest(thatop+miza+on(could(possibly(provide(be\er(results.NOOPhOI OEtOBu2BOTfNEt3NOOPhOIOEtOTiCl4iPr2NEtNo ReactionNo ReactionCH2Cl2, -78oC or rtCH2Cl2, -78oC or rtNOOPhOI OEtOLDATHF, -40oCNOOPhOOEtOAfter Several Hours40-60 % Conversion85:15 R/S80:20 E/ZA]er(more(than(60(experiments...Op5mal(Condi5ons•Enolate(forma+on(using(the(base(LiN(SiMe3)2•The(enolate(should(contain(the(Evans(chiral(oxizolidinone(or(the(Vilarrasa(chiralauxiliary.•The(solvent(system(9:1(CH2Cl2/THF(is(op+mal*Unless( otherwise(no ted,(reac+on(temperature(=(‐78oCPleas Note:Although in the paper, thismechanism is not a correctexplanation of the doublebond selectivity selectivity•The(method(presented(by(Vilarrasa(prevents(a(convenient(yetsurprisingly(overlooked(method(for(preparing(and(α,β‐unsaturatedesters(with(a(γ‐stereogenic(center.•A(mul+tude(of(related(chiral(b
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