Synthesis of Functionalized 1,3-Butadienes via Pd-Catalyzed Cross-Couplings of Substituted Allenic Esters in Water at Room Temperature
作者:Daniel J. Lippincott、Roscoe T. H. Linstadt、Michael R. Maser、Fabrice Gallou、Bruce H. Lipshutz
DOI:10.1021/acs.orglett.8b01377
日期:2018.8.17
responsible, mild method for the synthesis of functionalized 1,3-butadienes is presented. It utilizes allenic esters of varying substitution patterns, as well as a wide range of boron-based nucleophiles under palladium catalysis, generating sp–sp2, sp2–sp2, and sp2–sp3 bonds. Functional group tolerance measured via robustness screening, along with roomtemperature and aqueous reaction conditions highlight
good to excellent yields. Alkenes react with 2 with complete retention of configuration. The [2+2] cycloaddition is concluded to proceed via a concerted [(pi(2s)+pi(2s))(allene) + pi(2s)] Huckel transition state on the basis of experimental evidences and quantum mechanical methods. Some highly polarized enones and nitrile oxide, on the other hand, react with 2 selectively at the internal C(4)=C(alpha)
Organocatalytic Alkynylation of Aldehydes and Ketones under Phase-Transfer Catalytic Conditions
作者:Torsten Weil、Peter R. Schreiner
DOI:10.1002/ejoc.200500064
日期:2005.6
We developed alkynylations of various aldehydes and ketones under practical phase-transfer conditions at room temperature. The straightforward methodology combines one-pot synthesis and simple workup with good to excellent yields for propargylic alcohols derived fromaliphaticaldehydes and ketones. Even aromaticaldehydes and ketones could be transformed to the corresponding propargylic alcohols in
Preparation of lactones via tricarbonyliron–lactone complexes
作者:Gary D. Annis、Steven V. Ley、Christopher R. Self、Ramamoorthy Sivaramakrishnan
DOI:10.1039/p19810000270
日期:——
A number of tricarbonyliron–lactonecomplexes have been prepared from vinyl oxirans by treatment with pentacarbonyliron. In certain cases two η3-allyl complexes were isolated from a single vinyl oxiran. Oxidation of the complexes by cerium(IV) ammonium nitrate in acetonitrile leads predominantly to β-lactones. The stereochemical integrity of the initial complexes is reflected in the formation of the
Fully Substituted Pyranones via Quasi-Heterogeneous Genuinely Ligand-Free Migita–Stille Coupling of Iodoacrylates
作者:Jiří Kratochvíl、Zdeněk Novák、Mukund Ghavre、Lucie Nováková、Aleš Růžička、Jiří Kuneš、Milan Pour
DOI:10.1021/ol5035113
日期:2015.2.6
Migita-Stille coupling of (Z)-β-iodoacrylates with (E)-α-stannyl allylic alcohols to furnish 5-alkylidene-4-substituted-5,6-dihydro-2H-pyran-2-ones is efficiently catalyzed by 2% Pd black in DMF, while Pd(PPh3)4 is inactive. Heterogeneous Pd released in solution is most likely responsible for the catalysis. The reaction is applicable to other substrates, without having to resort to ligands, additives, and/or solid support for Pd. The resulting pyranones can be rearranged to fully functionalized pyranones in another single step.