Mild and Efficient Molybdenum-Mediated Pauson−Khand-Type Reaction

Departamento de Química Orgánica, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain.
Organic Letters (Impact Factor: 6.36). 03/2005; 7(3):431-4. DOI: 10.1021/ol047678u
Source: PubMed


[reaction: see text] The molybdenum-mediated Pauson-Khand reaction promoted by Mo(CO)3(DMF)3 takes place under very mild conditions in the absence of any promoter. High yields in Pauson-Khand adducts are obtained in the cyclization of a wide variety of functionalized 1,6- and 1,7-enynes. Enynes bearing electron withdrawing groups at the alkene terminus are particularly good substrates.

8 Reads
  • [Show abstract] [Hide abstract]
    ABSTRACT: Although 1-ethynyl-2-allenylbenzenes readily undergo Myers–Saito or Schmittel cyclization under mild conditions, cyclocarbonylation of these moieties to 1H-cyclopenta[a]inden-2-ones proceeds smoothly using suitable molybdenum carbonyl reagents, with Mo(CO)3(CH3CN)3 being the most efficient. The yields of desired bicyclic ketones were up to 87–93%.
    Tetrahedron Letters 11/2005; 46(46):7985-7988. DOI:10.1016/j.tetlet.2005.09.068 · 2.38 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A comprehensive review of recent chemistry of α, β-unsaturated sulfoxides and sulfones is presented. Emphasis has been placed on new reactions and strategies, stereo- and enantio-selective reactions, and emerging areas of interest such as metal-mediated asymmetric synthesis, solid-phase organic synthesis (SPOS), and cascade or ‘Domino’ reactions.
    ChemInform 11/2005; 26(2):163-185. DOI:10.1080/17415990500100115
  • [Show abstract] [Hide abstract]
    ABSTRACT: gamma-Functionalized alpha,beta-unsaturated nitriles are prepared diastereoselectively and enantiospecifically from enantioenriched cyanohydrin-O-phosphates and carbonates derived from alpha,beta-unsaturated aldehydes, either by palladium or iridium-catalyzed nucleophilic allylic substitution reactions with different nucleophiles. Appropriate reaction conditions for dibenzylamine, benzylamine, sodium azide, NaOAc, tetra-n-butylammonium acetate (TBAA), the corresponding sodium salts of phenol and N-hydroxysuccinimide and the carbonucleophile sodium dimethyl malonate are described. Different substituted O-protected cyanohydrins, such as carbonates and phosphates, derived from crotonaldehyde, (E)-hex-2-enal, oct-2-enal, 2-methylbut-2-enal, and cinnamaldehyde are used as allylic substrates. The substitution takes place with total retention of the configuration for the (E)-gamma-functionalized nitriles and with inversion of the configuration for the Z-isomers. In general, cyanohydrin-O-phosphates are the materials of choice to get the highest E-diastereoselectivity. Dibenzylamine is the best nucleophile for the synthesis of gamma-nitrogenated alpha,beta-unsaturated nitriles in the presence of either palladium or iridium catalysts when aliphatic compounds and cinnamaldehyde derivative are used (up to 98% dr). For the synthesis of gamma-oxygenated alpha,beta-unsaturated nitriles sodium or TBAA the reagents are selected to avoid epimerizations in up to 76% dr. Finally, the Tsuji-Trost reaction with sodium malonate works only under palladium catalysis in up to 70% dr.
    The Journal of Organic Chemistry 06/2006; 71(10):3837-48. DOI:10.1021/jo060239j · 4.72 Impact Factor
Show more