18321-36-3Relevant articles and documents
Stereo and regioselectivity in the phenylation of cationic allylpalladium(II) α-diimine complexes by tetraphenylborate anion
Crociani, Bruno,Antonaroli, Simonetta,Bianca, Francesca Di,Fontana, Alberta
, p. 21 - 26 (1993)
The reaction of the cationic complex 3-cyclohexenyl>(py-2-CH=NC6H4OMe-4)>+ (1) with BPh4- in the presence of fumaronitrile yields trans-3-methoxy-6-phenylcyclohexene (2a) and trans-4-methoxy-3-phenyl-cycohexene (2b), in ca. 1:1 molar ratio.The trans stereochemistry of these products implies that the phenylation of the allyl ligand involves prior transfer of a phenyl group from BPh4- to the metal, followed by reductive coupling of the organic moieties.In the reaction of 3-1,1-R1,R2-C3H3)(N-N')>+ (3) 1 = H, R2 = Ph, Me; R1 = R2 = Me> with BPh4- in the presence of activated olefins, both regioisomers PhCH2-CH=CR1R2 (4a) and CH2=CH-CR1R2Ph (4b) are formed with a relative ratio which depends essentially on the allylic substituents: R1 = H, R2 = Ph, 4a above 98percent; R1 = H, R2 = Me, 4a 75-67percent; R1 = R2 = Me, 4a 64-58percent.The regioisomer distribution is very little affected by the nature of the α-diimine, of the activated olefin, and of the solvent.For R1 = H and R2 = Ph, Me, the olefinic product 4a has a trans (E) geometry.These results have been interpreted in terms of reductive elimination occurring in the intermediate 3-1,1,R1,R2C3H3)(N-N')> with a ?-N monodentate α-diimine ligand.
Mode attack of atomic carbon on benzene rings
Armstrong, Brian M.
, p. 6007 - 6011 (1998)
Reaction of are generated carbon atoms with tert-butylbenzene, 4, gives 3-methyl-3-phenyl-1-butene, 5, and 1,1-dimethylindane, 6. Labeling studies and isotope effects demonstrate that 5 results from an insertion into a methyl C-H bond followed by 1,2 hydrogen shift while 6 arises from initial ortho C-H insertion followed by intramolecular insertion into a methyl C-H bend. When fluoroboric acid is added to the 77 K matrix of 4 + C, tert-butyltropylium fluoroborate, 18, is formed. Labeling studies indicate that 18 results from initial insertion of C into meta and para C-H bonds of 4 followed by ring expansion to cycloheptatetraenes which are subsequently protonated. The reaction of C with benzene gives similar results, indicating that initial C-H insertion is the preferred mode of attack of atomic carbon on benzene rings.
Reactivity of mixed organozinc and mixed organocopper reagents: 14. Phosphine-nickel catalyzed aryl-allyl coupling of (n-butyl)(aryl)zincs. Ligand and substrate control on the group selectivity and regioselectivity
Kalkan, Melike,Erdik, Ender
, p. 28 - 36 (2016/06/09)
The group selectivity and regioselectivity in the allylation of mixed (n-butyl)(aryl)zinc reagents in THF depends on the nickel catalyst type and also on nature of the allylic substrate. Allylation of (n-butyl)(phenyl)zinc reagent with alkyl substituted primary allylic chlorides and acetates in the presence of NiCl2(dppf) catalysis affords the phenyl coupling product with γ-selectivity. However, allylation with aryl substituted primary allylic substrates results in both phenyl- and alkyl-coupling products with medium α-selectivity in the presence of NiCl2(dppf) catalysis whereas phenyl coupling product is formed with α-selectivity in the presence of NiCl2(Ph3P)2 catalysis. This new NiCl2(dppf) catalyzed protocol for γ-selective aryl allylation of (n-butyl)(aryl)zinc reagents with alkyl substituted primary allylic chlorides in THF at room temperature provides an atom economic alternative to allylation of (aryl)2Zn reagents. A mechanism for the dependence of group selectivity and regioselectivity of Ni catalyzed allylation of (n-butyl)(aryl)zinc reagents on the catalyst ligand and the substrate was proposed.
Catalyst-free suzuki-type coupling of allylic bromides with arylboronic acids
Scrivanti, Alberto,Beghetto, Valentina,Bertoldini, Matteo,Matteoli, Ugo
supporting information; experimental part, p. 264 - 268 (2012/02/04)
The coupling of arylboronic acids with electron-rich allylic bromides is accomplished in the absence of any transition-metal catalyst through conventional heating. The reaction is completely regioselective, affording only the α-coupled product, and can be carried out under mild aerobic conditions in an organic solvent; the presence of a base is required. Copyright
