49826-80-4Relevant academic research and scientific papers
Silver-catalyzed benzylation and allylation of tertiary alkyl bromides with organozinc reagents
Mitamura, Yukihiro,Asada, Yoshihiro,Murakami, Kei,Someya, Hidenori,Yorimitsu, Hideki,Oshima, Koichiro
, p. 1487 - 1493 (2011/07/07)
Silver salts catalyze the benzylation and allylation of tertiary alkyl bromides with organozinc reagents. The reactions create quaternary carbon centers efficiently. Treatment of gem-dibromoalkanes with benzylic or allylic zinc reagents under silver catalysis leads to dibenzylation or diallylation. The functional-group compatibility of the present reactions is wider than that of the previous reactions with Grignard reagents.
Palladium-Catalyzed isomerization of exo-methylenic allylic alcohols
Fordred, Paul S.,Niyadurupola, D.Gangani,Wisedale, Richard,Bull, Stevend
scheme or table, p. 2310 - 2314 (2009/12/27)
Treatment of allylic alcohols containing a 1,1-disubstituted alkene with a palladium catalyst and hydrogen gas (1 bar) results in facile isomerization to their corresponding trisubstituted (E)-allylic alcohols, along with small amounts of the corresponding hydrogenated products.
Silver-catalyzed benzylation and allylation reactions of tertiary and secondary alkyl halides with grignard reagents
Someya, Hidenori,Ohmiya, Hirohisa,Yorimitsu, Hideki,Oshima, Koichiro
scheme or table, p. 969 - 971 (2009/04/10)
Treatment of alkyl halides, including tertiary alkyl bromides, with benzylic or allylic Grignard reagent in the presence of a catalytic amount of silver nitrate in ether yielded the corresponding cross-coupling products in high yields. The coupling reactions of tertiary alkyl halides provide efficient access to quaternary carbon centers.
Cobalt-catalyzed cross-coupling reactions of alkyl halides with allylic and benzylic grignard reagents and their application to tandem radical cyclization/cross-coupling reactions
Ohmiya, Hirohisa,Tsuji, Takashi,Yorimitsu, Hideki,Oshima, Koichiro
, p. 5640 - 5648 (2007/10/03)
Details of cobalt-catalyzed cross-coupling reactions of alkyl halides with allylic Grignard reagents are disclosed. A combination of cobalt(II) chloride and 1,2-bis(diphenylphosphino)ethane (DPPE) or 1,3-bis(diphenylphosphino)propane (DPPP) is suitable as a precatalyst and allows secondary and tertiary alkyl halides-as well as primary ones-to be employed as coupling partners for allyl Grignard reagents. The reaction offers a facile synthesis of quaternary carbon centers. which has practically never been possible with palladium, nickel, and copper catalysts. Benzyl, methallyl, and crotyl Grignard reagents can all couple with alkyl halides. The benzylation definitely requires DPPE or DPPP as a ligand. The reaction mechanism should include the generation of an alkyl radical from the parent alkyl halide. The mechanism can be interpreted in terms of a tandem radical cyclization/cross-coupling reaction. In addition, serendipitous tandem radical cyclization/cyclopropanation/carbonyl allylation of 5-alkoxy-6-halo-4-oxa-1-hexene derivatives is also described. The intermediacy of a carbon-centered radical results in the loss of the original stereochemistry of the parent alkyl halides, creating the potential for asymmetric cross-coupling of racemic alkyl halides.
Enantioselective carbometalation of cinnamyl derivatives: New access to chiral disubstituted cyclopropanes - Configurational stability of benzylic organozinc halides
Norsikian, Stephanie,Marek, Ilan,Klein, Sophie,Poisson, Jean F.,Normant, Jean F.
, p. 2055 - 2068 (2007/10/03)
A stoichiometric or catalytic amount of (-)-sparteine can serve asa promoter for the enantioselective carbolithiation of cinnamyl derivatives by primary and secondary organolithium compounds. The enantiofacial choice of the addition reaction is dependent on the stereochemistry of the initial double bond. The resulting benzylic organolithium compounds can be derivatized to a linear phenylated chain that bears two contiguous stereogenic centers with given configurations. The use of the dimethyl acetal of the (E)-cinnamyl alcohol allows the highest enantioselective carbolithiation and by simply warming the reaction mixture to room temperature, the resulting benzylic organo-lithium intermediate undergoes a 1,3-elimination to give the chiral disubstituted cyclopropane in high enantiomeric excess (90-95% ee). Another significant finding is the observation that the Li-Zn transmetalation in a benzylic species occurs with inversion of configuration, and the corresponding acyclic benzylic zinc halides have observable configurational stability at - 30°C.
Enantioselective carbolithiation of β-alkylated styrene
Norsikian, Stephanie,Marek, Ilane,Normant, Jean-F.
, p. 7523 - 7526 (2007/10/03)
Stoichiometric or catalytic amounts of (-) sparteine serve as promoter for enantioselective carbolithiation of β-alkylated, non functionalized styrene.
