The utility of the new class of chiral ligand, tethered bis(8-quinolinol) (TBOxH), is further explored. Its chromium complex, TBOxCr(III)Cl, effectively catalyzes the Nozaki-Hiyama allylation reactions of various aldehydes at room temperature with high yield (up to 95%) and high enantioselectivity (up to 99% ee). The scope of the present method is shown to be wide, and this method represents an efficient
Petasis Borono-Mannich Reaction and Allylation of Carbonyl Compounds via Transient Allyl Boronates Generated by Palladium-Catalyzed Substitution of Allyl Alcohols. An Efficient One-Pot Route to Stereodefined α-Amino Acids and Homoallyl Alcohols
作者:Nicklas Selander、Andreas Kipke、Sara Sebelius、Kálmán J. Szabó
DOI:10.1021/ja074917a
日期:2007.11.1
was designed by integration of the pincer-complex-catalyzed borylation of allyl alcohols in the Petasis borono-Mannich reaction and in allylation of aldehydes and ketones. These procedures are suitable for one-pot synthesis of alpha-amino acids and homoallyl alcohols from easily available allyl alcohol, amine, aldehyde, or ketone substrates. In the presented transformations, the active allylating agents
Transformation of Zirconocene−Olefin Complexes into Zirconocene Allyl Hydride and Their Use as Dual Nucleophilic Reagents: Reactions with Acid Chloride and 1,4-Diketone
Zirconocene-olefin complexes Cp2Zr(H2C=CHR), prepared in benzene-THF at 0 degreesC, react with acid chlorides to provide homoallylic alcohols. The key is an equilibrium between the zirconocene-olefin complexes and the corresponding zirconocene allyl hydride complexes via allylic C-H bond cleavage of the coordinating alkenes. Furthermore, the zirconocene-olefin complexes are also available for the reaction with 1,4-diketone to afford anti-1,4-diols with excellent diastereoselectivity. Thus, Cp2Zr(H2C CHR) serves as a donor of both hydride and an allylic group. These reactions also proceed efficiently by using zirconocene-olefin complexes, derived from Cp2ZrCl2, Mg metal, and 1-alkenes.
Conversion of Acid Chloride into Homoallylic Alcohol via Allylic C−H Bond Activation of Alkene with a Zirconocene Complex
Palladium-Catalyzed Oxidative Borylation of Allylic C–H Bonds in Alkenes
作者:Lujia Mao、Rüdiger Bertermann、Simon G. Rachor、Kálmán J. Szabó、Todd B. Marder
DOI:10.1021/acs.orglett.7b03296
日期:2017.12.15
palladium pincer complex-catalyzed allylic C–H borylation of alkenes. The transformation exhibits high regio- and stereoselectivity with a variety of linear alkenes. A synthetically useful feature of this allylic C–H borylation method is that all allyl-Bpin products can be isolated in usually high yields. Preliminary mechanistic studies indicate that this C–H borylation reaction proceeds via Pd(IV) pincer