29843-83-2Relevant academic research and scientific papers
Conjugate Addition Reactions of Allylic Copper Species Derived from Grignard Reagents: Synthetic and Spectroscopic Aspects
Lipshutz, Bruce H.,Hackmann, Claus
, p. 7437 - 7444 (2007/10/02)
A general study on the 1,4-addition chemistry of allyl, methallyl, crotyl, and prenyl Grignard-derived organocopper reagents has been conducted.While diallylic cuprates formed from such species are not effective Michael donors, the 1:1:1 combination of an
Allylbarium reagents: Unprecedented regio- and stereoselective allylation reactions of carbonyl compounds
Yanagisawa, Akira,Habaue, Shigeki,Yasue, Katsutaka,Yamamoto, Hisashi
, p. 6130 - 6141 (2007/10/02)
The first direct preparation of allylbarium reagents by reaction of in situ generated reactive barium with various allylic chlorides and their new and unexpected selective allylation reactions with carbonyl compounds are disclosed. Highly reactive barium was readily prepared by the reduction of barium iodide with 2 equiv of lithium biphenylide in dry THF at room temperature. A variety of carbonyl compounds reacted with barium reagents generated from (E)- or (Z)-allylic chlorides in THF at -78 °C. All reactions resulted in high yields with remarkable α-selectivities not only with aldehydes but also with ketones. The double bond geometry of the starting allylic chloride was completely retained in each case. Stereochemically homogeneous (E)- and (Z)-β,γ-unsaturated carboxylic acids were easily prepared in good yields by highly α-selective carboxylation of allylic barium reagents with carbon dioxide. A selective Michael addition reaction with α,β-unsaturated cycloalkanone was also achieved using an allylbarium reagent. Treatment of 2-cyclopentenone (1 equiv) with allylbarium chloride (2 equiv) in THF at -78 °C for 20 min afforded 3-allylcyclopentanone in 94% yield with a 1,4/1,2 ratio of >99/1. Furthermore, the in situ generated barium enolate was efficiently trapped with various kinds of electrophiles (Me2C=CHCH2Br, nC5H11CHO, and CH3COCl).
Direct formation of highly functionalized allylic organocopper reagents from allylic chlorides and acetates
Stack, Douglas E.,Dawson, Bryan T.,Rieke, Reuben D.
, p. 5110 - 5116 (2007/10/02)
The direct formation of highly functionalized allylic. organocopper reagents has been carried out using a highly active form of zerovalent topper (Cu*). The cold-temperature reduction of CuCN-nLiX complexes by lithium naphthalenide in THF under an argon atmosphere produces the Cu* complex, which reacts rapidly with primary and secondary allyl chlorides at -100 °C with little homocoupling. Allyl, methallyl, and crotyl acetates also oxidatively add with Cu* at low temperatures to afford the corresponding organocopper reagent. Significantly, the allyl chlorides can contain a wide array of functional groups including ketones. α,β-unsaturated ketones, epoxides, alkyl acetates, esters, alkyl chlorides, nitriles, and carbamates. The cross-coupling of the highly functionalized allylic organocopper reagents with various electrophiles proceeds in excellent yields.
New methodology for conjugate additions of allylic ligands to α,β-unsaturated ketones: Synthetic and spectroscopic studies
Lipshutz, Bruce H.,Ellsworth, Edmund L.,Dimock, Stuart H.,Smith, Robin A.J.
, p. 4404 - 4410 (2007/10/02)
Michael additions of allylic ligands, including allyl, methallyl, crotyl, and prenyl systems, to a variety of α,β-unsaturated ketones can be effected in synthetically useful yields with allylcopper reagents in the presence of trimethylchlorosilane. Low-te
