50910-65-1Relevant academic research and scientific papers
The copper mediated Barbier reactions of α,β-unsaturated ketones: Regioselective conjugate and 1,2-addition
Costello, Declan P.,Geraghty, Niall W. A.
, p. 3083 - 3096 (2007/10/03)
The one-pot reaction of isophorone and other α,β-unsaturated ketones with alkyl and aryl halides in the presence of magnesium and a copper salt ('Barbier' conditions) leads to the regiospecific formation of 1,4-addition products; the use of lithium leads to regioselective 1,2-addition.
Nickel-catalysed conjugate addition to trimethylaluminum to sterically hindered α,β-unsaturated ketones
Flemming,Kabbara,Nickish,Neh,Westermann
, p. 317 - 320 (2007/10/02)
Nickel acetylacetonate is an efficient catalyst for the 1,4-addition of trimethylaluminum to α,β-unsaturated ketones. The reaction is strongly solvent dependent and gives best results in tetrahydrofuran or ethyl acetate. The reaction is especially useful for the nucleophilic 1,4-methyl transfer to sterically hindered enones. A β-cuparenone synthesis via conjugate methyl group addition to an enone precursor is described.
SAMARIUM(II) IODIDE PROMOTED RADICAL RING OPENING REACTIONS OF CYCLOPROPYL KETONES
Batey, Robert A.,Motherwell, William B.
, p. 6649 - 6652 (2007/10/02)
Radical ring opening reactions of cyclopropyl ketones mediated by samarium(II) iodide-induced single electron transfer have permitted the elaboration of a tandem rearrangement cyclisation strategy.The resultant samarium enolates may be effectively quenched on oxygen or carbon by electrophiles.Key Words: Samarium(II) Iodide Reduction; Cyclopropylcarbinyl Radical Rearrangement; Cyclopropyl Ketone; Radical Cyclisation; Samarium Enolate.
Samarium(II) iodide promoted radical ring opening reactions of cyclopropyl ketones
Batey,Motherwell
, p. 6211 - 6214 (2007/10/02)
Radical ring opening reactions of cyclopropyl ketones mediated by samarium(II) iodide-induced single electron transfer have permitted the elaboration of a tandem rearrangement cyclisation strategy. The resultant samarium enolates may be effectively quenched on oxygen or carbon by electrophiles.
Amphiphilic Reactions by Means of Exceptionally Bulky Organoaluminum Reagents. Rational Approach for Obtaining Unusual Equatorial, Anti-Cram, and 1,4 Selectivity in Carbonyl Alkylation
Maruoka, Keiji,Itoh, Takayuki,Sakurai, Minoru,Nonoshita, Katsumasa,Yamamoto, Hisashi
, p. 3588 - 3597 (2007/10/02)
Exceptionally bulky, oxygenophilic organoaluminum reagents, methylaluminum bis(2,6-di-tert-4-alkylphenoxide) (MAD and MAT), have been successfully utilized for stereoselective activation of carbonyl moiety.Combination of MAD or MAT with carbon nucleophiles such as organolithiums or Grignard reagents generates a new amphiphilic reaction system in which the alkylation may be interpreted as the nucleophilic addition of a reactive organometallic compound to an electrophilically activated carbonyl substrate in order to account for the regio- and stereochemical consequences.In contrast to the ordinary alkylations, the amphilic alkylation disclosed herein would be categorized into the new, yet unexplored class of alkylation that exhibits high chemoselectivity to carbonyl compounds, and more significantly it allows excellent equatorial and anti-Cram selectivity in carbonyl alkylations, hitherto difficult by the existing methodologies.Further, unusual conjugate addition of organolithium reagents to α,β-unsaturated carbonyl compounds has been accomplished by using the amphiphilic reaction system.
UNUSUAL CONJUGATE ADDITION OF ORGANOLITHIUM REAGENT TO α,β-UNSATURATED KETONE
Maruoka, Keiji,Nonoshita, Katsumasa,Yamamoto, Hisashi
, p. 5723 - 5726 (2007/10/02)
The conjugate addition of organolithium reagent to α,β-unsaturated ketone has been accomplished with methylaluminum bis(2,6-di-tert-butyl-4-alkylphenoxide) (MAD and MAT).Here combination of alkyllithium and MAD (or MAT) constitutes an amphiphilic system that allows to exhibit unusual selectivity in the alkylation of enones with alkyllithium.
1,4-Addition of Triorganozincates and Silyldiorganozincates to α,β-Unsaturated Ketones
Tueckmantel, Werner,Oshima, Koichiro,Nozaki, Hitosi
, p. 1581 - 1593 (2007/10/02)
Lithium and magnesium triorganozincates, prepared by combination of ZnCl2(TMEDA) with 3 molar equivalents of RLi or RMgX, or from dialkylzinc and 1 molar equivalent of RLi or RMgX, react with 2-cyclohexen-1-one (1) under mild conditions to produce moderate to good yields of the 1,4-addition products 2.The approximate reactivity order obtained from the product distribution using unsymmetrical zincates is tBuCH2 tBu, Me Me2PhSi.The latter groups are transferred with good selectivity from mixed reagents derived from Me2Zn.This sequence differs strikingly from that exhibited by unsymmetrical cuprates which transfer neopentyl very easily, and also tert-butyl more easily than the corresponding zincates.The methylation with Me3ZnLi is catalyzed by cobalt complexes.Other enones (7-13) generally give poor yields, and the cobalt-catalyzed methylation of isophorone (3) is complicated by a Kharasch-type deconjugation.Mixed silyldialkylzincates, Me2PhSiZnR2Li, produce the β-silyl ketones from a variety of unhindered or moderately hindered enones in practically useful yields; one example of an α,β-unsaturated ester (12) is also included.
