Syn-Stereocontrolled dihydroxylation of Baylis-Hillman adducts
作者:István E. Markó、Paul R. Giles、Zdenek Janousek、Nigel J. Hindley、Jean-Paul Declercq、Bernard Tinant、Janine Feneau-Dupont、John S. Svendsen
DOI:10.1002/recl.19951140418
日期:——
The hydroxylation of Baylis-Hillmanadducts 1 is shown to proceed with high levels of diastereocontrol. A mechanistic rationale to explain this selectivity is discussed.
Distinct reactivity of Morita–Baylis–Hillman acetates as a novel C2 component in amine-catalyzed [2 + 2 + 2] and [2 + 4] annulations
作者:Rongshun Chen、Silong Xu、Liyi Wang、Yuhai Tang、Zhengjie He
DOI:10.1039/c3cc41419a
日期:——
Amine-catalyzed [2 + 2 + 2] and [2 + 4] annulations of MoritaâBaylisâHillman (MBH) acetates with cyano activated alkenes and 1,3-azadienes have been developed to provide cyclohexanes and tetrahydropyridines. In the annulations, MBH acetates serve as a novel C2 component with an inactive homoallylic methyl involved in the bond formation.
Abstract A stereospecific synthesis of enones 3 by coupling reaction of α-acetoxy alkyl methylvinylketones 2 and Gilman or Grignard reagents in the presence of a catalytic amount of copper (I) salt at low temperature, is described.
Stereoselective Synthesis of Medium-Sized Cyclic Compounds by Means of Tandem Reactions of a Cyclic Oxosulfonium Ylide with Acetates of Baylis−Hillman Adducts
five-membered cyclic oxosulfonium ylide 3 with β-acetoxy-α-methylene ketones in the presence of two equimolar amounts of base afforded the cycloheptene oxide derivatives 7a−i as single stereoisomers in 19−77% yields. The products were considered to form through a Michael-type addition of the ylide, followed by elimination of the acetoxy group and an intramolecular Corey−Chaykovsky reaction. On the
[GRAPHICS]The reaction of the five-membered cyclic oxosulfonium ylide 2 with alpha-methylene-beta-acetoxy ketones in the presence of two equimolar amounts of base afforded the cycloheptene oxide derivatives with stereoselectivity in 19-74% yield via a Michael-type addition of the ylide followed by elimination of the acetoxy group and an intramolecular Corey-Chaykovsky reaction.