Stereoselective arylation

Alkynes react with electrophilic selenium reagents such as phenylselenenyl tosylate.155 The reaction occurs with anti stereoselectivity. Aryl-substituted alkynes are regioselective, but alkyl-substituted alkynes are not. 

Intermolecular Stereoselective Aryl Coupling 2.1.1. Internal Asymmetric Induction with Chiral Substrates 2.1.1.1. Dimerization of Chiral Aryl Compounds... 

Table 1. Intramolecular Stereoselective Aryl Coupling with Thallium(III) Oxide/Trifluo-roacetic Acid (Method A)...

Table 2. Intramolecular Stereoselective Aryl Couplings with Various Reagents (Methods A-E)...

G. Casiraghi, M. Cornia, G. Rassu, L. Zetta, G. G. Fava, and M. F. Belicchi, Stereoselective arylation of pyranoid glycals using bromomagnesium phenolates an entry to 2,3-unsaturated C-a-glycopyranosylarenes, Carbohydr. Res., 191 (1989) 243-251. 

H. -J. Altenbach, Regio- and Stereoselective Aryl Coupling, in Organic Synthesis Highlights (J. Mulzer,... 

H.-J. Altenbach, Regio- and Stereoselective Aryl Coupling, in Organic Synthesis Highlights (J. Mulzer, H.-J. Altenbach, M. Braun, K. Krohn, H.-U. RciBig, Eds.), VCH, Weinheim, New York, 1991, 181-185. 

An interesting method for the simultaneous formation of two C—C bonds is represented by the regio- and stereoselective arylation of 1,4-cyclohexadiene with iodobenzene and diethyl malonate. After oxidative insertion of palladium(O) into the aryl - iodine bond the arylpalladium species generated adds syn to a double bond and a subsequent syn palladium migration forms a ttK-woTt-allylpalladium intermediate. The palladium is displaced with inversion by the soft carbanion to produce the /ran.v-cy cl oh ex en e derivative 4 in high yield26, at the same time regenerating an active palladium(O) catalyst for the next catalytic cycle. 

Highly stereoselective arylation reactions were reported, as shown in Equation 5.46. With an optically active diamine ligand, a modest asymmetric induction was observed (Equation 5.47). An asymmetric synthesis of a synthetic prostaglandin AH 13 205 was accomplished using the diastereoselective cobalt-catalyzed cycliza-tion/arylation sequence as key step [55]. 

Scheme 12.16 Stereoselective arylations of cyclic allylic substrates [32],...

Keywords Arenediazonium tetrafluoroborate salts, olefins, palladium acetate, triton X-100, water, room temperature, Pd-nanoparticles, Matsuda-Heck coupling, arylation of olefins, stereoselectivity, aryl substituted olefins... 

Scheme 3.16 Highly stereoselective arylation of (S)-proline and complimentary highly...

SCHEME 5 Regio- and stereoselective arylation of allyl acetates. 

Once we realized that the substrate-directed arylation strategy could promote a rapid increase in the structural complexity of the allylic acetates, we decided to apply it in the total synthesis of biologically active kavalactones, represented by compound 18 in Scheme 7. The key step would be the stereoselective arylation of the substrate 19, which would lead us directly to the core skeleton of these natural products. 

Stereoselective Arylation of IV-Protected Allylic Amine Derivatives... 

In summary, the stereoselective arylation of allylamine derivatives was accomplished by a substrate-directed Heck-Matsuda strategy. The data we obtained from these studies suggest that the origin for the regiocontrol in favor... 

Our first applications of this new method have allowed the successful regio- and stereoselective arylation of acyclic allylic esters and A -protected allylamine derivatives. As a consequence of the high synthetic value of the arylated products, they were applied in the total synthesis of several bioactive compounds. Starting from allyUc esters, the synthesis of kavalactones such as the yagonine (27), methysticin (28), and dehydromethysticine (29) was accomplished in a straightforward way. Additionally, the y-arylated allylamine derivatives were applied to the total synthesis of the bioactive compounds naftifine (68), abamine (75), abamine SG (77), cinacalcet hydrochloride (85), and alverine (91). 

This methodology was also applied to the stereoselective arylation of substituted cyclic compounds to provide highly complex aryl-substituted cyclo-pentene scaffolds with total control of the double bond position. This unique substrate-directed Heck-Matsuda reaction was applied in the total synthesis of the SlPi agonist VPC01091 (130). 

Oi and Inoue demonstrated that similar mthenium(II) catalysts could catalyse the arylation of sp C-H bond of 2-alkenyl pyridine without Heck type reaction to produce arylated alkenes. The alkene C-H bond facing the pyridine nitrogen was stereoselectively arylated suggesting a cyclometaUated ruthenium(II) intermediate (Scheme 1) [60]. 

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