Nickel- or palladium-catalyzed cross coupling. 31. Palladium- or nickel-catalyzed reactions of alkenylmetals with unsaturated organic halides as a selective route to arylated alkenes and conjugated dienes: scope, limitations, and mechanism
作者:Eiichi Negishi、Tamotsu Takahashi、Shigeru Baba、David E. Van Horn、Nobuhisa Okukado
DOI:10.1021/ja00242a024
日期:1987.4
Al, Zr, and Zn were 2, 3, and > 2000 mmol of (E)-1-octenylbenzene (8) per mmol of Pd(PPh/sub3/)/sub 4/ per hour at room temperature, respectively. The stoichiometric reaction of PhPd(PPh/sub3/)/sub 2/I (6) with 1.2 equiv of (E)-1-octenylzinc chloride (7) in a 2:1 mixture of CD/sub 2/Cl/sub2/ and THF was examined in detail. The reaction follows second-order kinetics (k/sub2/ = 2.9 L/(mol.min) at
Asymmetric Synthesis of Less Accessible α-Tertiary Amines from Alkynyl <i>Z-</i>
Ketimines
作者:Taichi Kano、Yusuke Aota、Keiji Maruoka
DOI:10.1002/anie.201710084
日期:2017.12.18
highly stereoselective synthesis of hitherto less accessible chiral α‐tertiary amines with multiple structurally similar linear carbon chains was achieved through chiral auxiliary mediated addition of organolithium reagents to the geometrically well‐controlled alkynyl Z‐ketimines. This stereoselective nucleophilic addition offers a general approach to the asymmetric synthesis of nitrogen‐containing
The reaction of Cl2Pd(PEt3)2 with 2 equiv of (E)-t-BuCHCHLi, t-BuCCLi, or MeLi gives the corresponding R12Pd(PEt3)2 in a nearly quantitative yield without producing R1R1, where R1 = (E)-t-BuCHCH, t-BuCC, or Me. The reaction of PhLi or PhZnCl gives Ph2Pd(PEt3)2 and biphenyl in approximately 90 and 10% yields, respectively. On the other hand, the corresponding reaction of Cl2Pd(PPh3)2 produces R1R1
Synthesis of α-Substituted Allylic Amines via a Modified Bruylants Reaction
作者:Claude Agami、François Couty、Gwilherm Evano
DOI:10.1021/ol0059908
日期:2000.7.1
iminium ion promoter from alpha-amino nitriles, is an efficient additive in the Bruylants reaction involving vinylic Grignards. Improved yields of allylic amines were obtained when the starting alpha-amino nitrile was treated with this silver salt prior to its reaction with the vinylic Grignard. This improvement was not observed in the case of acetylenic Grignards. The reactivity of other vinyl organometallics
Preparation of polyfunctional diorganomercurials and their transmetallation to diorganozincs. Applications to the preparation of optically active secon
作者:Michael J. Rozema、Duddu Rajagopal、Charles E. Tucker、Paul Knochel
DOI:10.1016/0022-328x(92)88002-z
日期:1992.10
Two new methods of preparation of functionalized diorganomercurials have been developed. The first method involves a substitution reaction of (ICH2)2Hg with zinc-copper reagents FG-RCu(CN)ZnI in THF/DMF at - 60-degrees-C. Functional groups such as an ester, nitrile, ketone, phosphonate, halide, and boronic ester are tolerated in this reaction. The second method involves a reductive transmetallation between polyfunctional organozinc halides and mercurous chloride (Hg2Cl2). This very convenient procedure provides a rapid route to various functionalized diorganomercurials in good yields (61-89% yield). The synthetic utility of these mercury organometallics is demonstrated. Their transmetallation with zinc dust (toluene, 80-degrees-C, 3-5 h) affords dialkylzincs which add enantioselectively to aldehydes in the presence of a catalytic amount (20 mol%) of the norephedrine derivative 13. This transmetallation can also be used to prepare stereoselectively (E)-alkenylzinc halides (> 98% E). Addition of Cl(H)ZrCp2 to (E)-5-chloropentenylzinc bromide in CH2Cl2 (25-degrees-C, 1 min) affords a 1,1-bimetallic of zinc and zirconium Cl(CH2)4CH(ZnBr)ZrCp2(Cl) which reacts stereoselectively with an aldehyde providing the (E)-disubstituted olefin (49% yield; 100% E).