Harvesting the Strain Installed by a Paternò−Büchi Step in a Synthetically Useful Way: High-Yielding Photoprotolytic Oxametathesis in Polycyclic Systems
摘要:
High-yielding one-pot photoinduced transformation of readily available endoaroyl and heteroaroyl Diels-Alder adducts into novel polycyclic aldehydes or their hemiacetals, decorated by carbo- and heterocyclic pendants, is described.
Silylium Ion-Catalyzed Challenging Diels–Alder Reactions: The Danger of Hidden Proton Catalysis with Strong Lewis Acids
作者:Ruth K. Schmidt、Kristine Müther、Christian Mück-Lichtenfeld、Stefan Grimme、Martin Oestreich
DOI:10.1021/ja211856m
日期:2012.3.7
Proton-catalyzed Diels-Alderreactions are not well-documented in the literature, and a representative survey employing TfOH is included here. The outcome of these catalyses is compared with our silylium ion-catalyzed Diels-Alderreactions, thereby clearly corroborating that hidden Brønsted acid catalysis is not operating with our Lewis acid. Several simple-looking but challenging Diels-Alderreactions with exceptionally
Achieving Enantioselectivity in Difficult Cyclohexa-1,3-diene Diels–Alder Reactions with Sulfur-Stabilized Silicon Cations as Lewis Acid Catalysts
作者:Polina Shaykhutdinova、Martin Oestreich
DOI:10.1021/acs.orglett.8b02945
日期:2018.11.16
A novel cationic silicon–sulfur Lewis pair with a chiral H8-binaphthyl backbone is reported. It catalyzes otherwise sluggish Diels–Alderreactions of cyclohexa-1,3-diene and chalcone derivatives in good yields and decent enantioselectivities (up to 81% ee). The enantioinduction is highest with a [1,1′-biphenyl]-4-yl substituent at the carbonyl carbon atom. This moiety can be later converted into a
Refinement of the Catalyst Backbone of Chiral Intramolecular Silicon-Sulfur Lewis Pairs: Improved Enantioselectivity in the Diels-Alder Reaction of Cyclohexa-1,3-diene and Chalcone Derivatives
Step by step. A new, structurally modified silicon cation intramolecularly stabilized by a sulfur donor catalyzes challenging Diels–Alder reactions of cyclohexa‐1,3‐diene and chalcone derivatives with improved enantiomeric excesses. The endo selectivity typically observed is inverted to exo with cyclopentadiene, and no enantioinduction is obtained.
Further Structural Modification of Sulfur-Stabilized Silicon Cations with Binaphthyl Backbones
作者:Polina Shaykhutdinova、Martin Oestreich
DOI:10.1055/s-0037-1610697
日期:2019.5
previously reported Lewis acids. Another silicon cation with a chiral spirocyclic backbone induces enantioselectivity in the same range but its synthesis is laborious. The synthesis and spectroscopic characterization of two novel cationic silicon–sulfur Lewis pairs with a chiral 4,4′-disubstituted binaphthyl silepine backbone are described. Both Lewis acids induce significant enantioselectivity in the model
Highly Selective Diels−Alder Reactions of Dienophiles with 1,3-Cyclohexadiene Mediated by Yb(OTf)<sub>3</sub>·2H<sub>2</sub>O and Ultrahigh Pressures
作者:Aaron C. Kinsman、Michael A. Kerr
DOI:10.1021/ol0065773
日期:2000.11.1
[GRAPHICS]Ultrahigh pressures and catalytic Yb(OTf)(3). 2H(2)O were found to mediate Diets-Alder reactions of various electron-deficient dienophiles with 1,3-cyclohexadiene to produce endo-bicyclo[2.2.2]oct-2-enes in moderate to excellent yield and selectivity. The proposed total synthesis of hapalindole Q based on bicyclo[2.2.2]oct-2-ene construction by Diels-Alder reaction and subsequent olefin cleavage is outlined, Preliminary results demonstrating the viability of this strategy are presented.