Phenylzinc chloride

Triflates are used for the reaction[470]. The 5-phenyltropone 609 is prepared by coupling of the triflate with phenylzinc chloride[471]. Instead of the expensive triflale, phenyl fluoroalkanesulfonate as a triflate equivalent is used for coupling[472]. Phenyl fluorosulfonate (610) is another reagent used for cou-pling[473]. 

In the reaction of the 1,1-dichloro-l-alkene 611 with phenylzinc chloride, only monoarylation takes place regioselectively to give the (Z)-l-chloro-l-phe-nylalkene 612[468,474],... 

The allylic esters 189 and 191 conjugated with cyclopropane undergo regio-selective reactions without opening the cyclopropane ring. The soft carbon nucleophiles are introduced at the terminal carbon to give 190, and phenylation with phenylzinc chloride takes place on the cyclopropane ring to form 192[120]. 

The catalytic asymmetric synthesis of allenes was first achieved by Elsevier and co-workers in 1989 [104]. A palladium-catalyzed cross-coupling reaction of an allenyl-metal compound 250 (M = ZnCl, MgCl or Cu) with iodobenzene in the presence of DIOP 251 gave 252 in 25% ee (Scheme 4.65). The synthesis of 252 by the reaction of 250 (M = Br) with phenylzinc chloride in the presence of a chiral palladium catalyst gave a quantitative conversion but very low enantiomeric excesses (3-9% ee). 

Theuseof DMPU (l,3-dimethyl-3,4,5,6-tetrahydro-2(l//)-pyrimidmone) as acosolvent in THF has been reported to increase the amination yield of arylzinc chlorides with Erdik and Omiir also reported competitive kinetic studies for the amination of substituted phenylmagnesium bromides and CuCN-catalyzed phenylzinc chlorides with acetone 0-(mesitylenesulfonyl)oxime 6f in THF and analyzed the rate data via the Hammett... 

O-propargyl-2-iodophenol in the presence of a palladium catalyst and phenylzinc chloride (3.30.) led to the formation of the 3-alkylidenedihydrobenzofurane in good yield (c.f 3.26.),37 The use of norbomene as capture reagent under similar conditions led to the formation of benzofurane bearing a tetracyclic hydrocarbon substituent.38... 

A 1,3-substituted allene, which has axial chirality instead of carbon central chirality, has been prepared by a palladium-catalyzed cross-coupling of 4,4-dimethylpenta-l,2-dienylzinc chloride (83) with phenyl iodide (5c) or by that of l-bromo-4,4-dimethylpenta- 1,2-diene (84) with phenylzinc chloride [60] (Scheme 8F.20). The highest enantiomeric purity (25% ee) of the allene (S)-85 was obtained in the former combination with (f ,/ )-diop (1) as chiral ligand. It is interesting that the enantiomeric purity was independent of the ratio of the reagents though the reaction seems to involve a kinetic resolution of the racemic 83. 

Alkylation of dihydropyranylacetates. The Pd(0)-catalyzed alkylation of allylic acetates by stabilized carbanions originally reported by Trost and Verhoeven (8,475 9, 451 -457)4 has been extended to alkylation of dihydropyranyl acetates as a route to natural C-glycopyranosides.5 Again the displacement is regioselective and results in net retention of configuration in reactions with most carbanions. However, alkylation with phenylzinc chloride or vinylzinc chloride occurs with inversion. 

Heck intramolecular cyclization. Silver carbonate or nitrate was added originally to tandem Heck arylation reactions to depress alkene isomerization, but they also improve selectivity in the -elimination step. Grigg et al.1 have used a number of useful additives such as triethylammonium chloride, sodium formate (15, 248), phenylzinc chloride, as well as silver(l) and thallium(I) salts. In fact, thallium(I) salts... 

Scheme 11.41 Cross-coupling of phenylzinc chloride via transmetallation.

Benzoylacrylic acid has been prepared by the condensation of acetophenone and chloral to l,l,l-trichloro-2-hydroxy-3-benz-oylpropane, followed by hydrolysis to the corresponding acid and dehydration by the action of iodine, potassium iodide, and sodium carbonate on 7-phenylisocrotonic acid by bromination of /3-benzoylpropionic acid and subsequent dehydrohalogena-tion 1 and by the action of phenylzinc chloride on maleic anhydride. The present method is based on the work of von Pech-mann and others. ... 

Whereas sodium indenide displays a stereoselectivity similar to phenylzinc chloride (see Table 26), sodium cyclopentadienide and 3-trimethylsilylindene act like soft carbanions. Both substrates 10 and 12 undergo allylic substitution with net retention of configuration to 1127 and 1328, respectively, via attack on the ally ligands of the intermediate 7t-allylpalladium complexes anti to the metal. Again, the ratio of the two possible diastereomers of structure 13 is unknown. 

Enantioselective catalysis with nucleophiles that attack the metal of the intermediate rr-allylpal-ladium complexes prior to allylic C-C bond formation has met with only limited success so far30-31. Phenylation of the allyl acetates 1 and 4 via re-allyl complexes with a me,sY -7r-allyl ligand using phenylzinc chloride and enantiomerically pure monophosphines 231 or 53a yield 3 and 6 of low enantiomeric excess, respectively. 

The final palladium-alkyl intermediate can also be trapped by hydride or carbanion reagents87,88,91. In intramolecular versions, this again leads to polycyclic products87,88 91. Thus, palladium-catalyzed polycyclization of aryl iodide 14 containing an enamide and additionally an alkene function leads, with complete stereocontrol, to tricyclic product 15 if the reaction is terminated with sodium formate, phenylzinc chloride or sodium tetraphenylborate (albeit in low yield)45. 

Recently, a new regioselective synthesis of 2-alkyl and 2-aryl 5-substituted pyridines was reported128. It involved the chemoselective reaction of commercially available 2,5-dibromopyridine with terminal acetylenes or phenylzinc chloride in the presence of Pd(0) (equation 110). However, this method does not allow the preparation of 2-methyl-5-... 

Method H is based on the really efficient Ni(dppf)-catalysed high-yielding Negishi reaction system. For instance, biphenyl-2-carbonitrile (154) was prepared from phenylzinc chloride (151) and 2-ehlorobenzonitrile (114) in 86% yield [49], Scheme 17. 

Phenyl group was introduced into position 2 by treatment of 2-bromoterguride with phenylzinc chloride under catalysis by palladium or nickel complexes— Figure 4 (Heindl et al., 1989). 

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