Cross-coupling, regiospecific

Scheme 31. Nickel-catalyzed O-aryl carbamate Crignard cross-coupling regiospecific access to 1,2,3- and 2,3-substituted naphthalenes.

Miyaura, N. Yamada, K. Suginome, H. Suzuki, A. Novel and convenient method for the stereo- and regiospecific synthesis of conjugated alkadienes and alkenynes via the Pd-catalyzed cross-coupling reaction of 1-alkenyl-boranes with bromoalkenes and bromoalk-ynesj. Am. Chem. Soc. 1985, 107, 972-980. 

Regiospecific generation of vinyl triflate 77 from ketones such as 53 and 54 was planned for the introduction of C-4 substituents via palla-dium(0)-catalyzed cross-coupling reactions to give dehydropyrrolidine enamide derivatives 78 which could be reduced stereospecifically to protected kainoid derivatives 79 (Scheme 33). 

Snieckus and Fu reported a new general and regiospecific synthesis of 9-phenanthrols involving direct ortho-metalation, Suzuki cross-coupling, and an LDA-mediated directed remote metalation sequence (Eq. (11)) [27]. 

Bis(pinacolato)diboron 8 also reacts with 1-halo-l-lithioalkenes 10 (available from 1,1-dihaloalkenes or 1-haloalkenes by halogen-metal exchange or metalation reaction, respectively) to afford 1,1-bismetalated dienes 11. These are readily converted into polysubstituted dienes through various transition metal-catalyzed carbon-carbon bond formations (Scheme 4) [29]. However, these seemingly attractive methods must not hide the problems of the stereochemistry and regiospecificity of the subsequent cross-coupling reactions. 

V. Snieckus and co-workers developed a new carbamoyl Baker-Venkataraman rearrangement, which allowed a general synthesis of substituted 4-hydroxycoumarins in moderate to good overall yields. The intermediate arylketones were efficiently prepared from arylcarbamates via directed ortho metallation and Negishi cross coupling. The overall sequence provided a regiospecific anionic Friedel-Crafts complement for the construction of ortho-acyl phenols and coumarins. 

Kalinin, A. V., Da Silva, A. J. M., Lopes, C. C., Lopes, R. S. C., Snieckus, V. Directed ortho metalation and cross coupling links. Carbamoyl rendition of the Baker-Venkataraman rearrangement. Regiospecific route to substituted 4-hydroxycoumarins. Tetrahedron Lett. 1998, 39, 4995 998. 

Regiospecific formation of poly(3-hexylthiophene) by a nickel-catalysed cross-coupling (Scheme 6)... 

The Af-isopropyl-Af-trimethylsilylcarbamoyl-DMG may be conveniently installed via treatment of a phenol with isopropyl isocyanate followed by a one-flask operation that begins the reaction with TMS triflate, lithiation with BuLi/TMEDA, and concludes with electrophile quench (eq 53). The application of this methodology was demonstrated for the synthesis of hydroxy-biaryls. The regiospecific construction of a diverse set of isomeric chlorodihydroxybiphenyls and polychlorinated diphenyls is reported by applying BuLi-mediated DoM protocols and Suzuki cross-coupling tactics on commercially available starting materials. ... 

The first synthesis of HT rr-P3AT (Scheme 9.1), known as the McCullough method was reported in 1992 (Scheme 9.1, Table 9.1, entry 1) [25,26]. The key to this method is the regiospecific generation of 2-bromo-5-bromomagnesio-3-alkylthiophene 3 from 2-bromo-3-alkylthiophene, which is then polymerized by Kumada and coworkers [27-29] cross-coupling methods using catalytic amounts of... 

Regiospecific cross-coupling of organotitanium trialkoxides with allylic functions <-... 

Unrau CM, Campbell MG, Snieckus V (1992) Directed ortho metalation - Suzuki cross coupling connections. Convenient regiospecific routes to functionalized m-and p-teraryls and m-quinquearyls. Tetrahedron Lett 33 2773-2776... 

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