Selectivity Tamaru

Further studies demonstrated the influence of the double-bond substitution on both the reactivity and the stereoselectivity of the reaction [78-81]. Tamaru and co-workers reported then that using the same PdCl2/CuCl2/MeOH system on butenol derivatives, with the double bond in either the terminal or an internal position, furnished selectively y-butyrol-actones. This dicarbonylation process most probably includes (i) a lactoniza-tion step and (ii) a methoxycarbonylation step, as displayed in Scheme 11 in which we clarify some intermediate steps on a representative example [82, 83]. The use of propylene oxide as an additive promotes this Pd-catalyzed dicarbonylation by playing the role of an HC1 quencher to maintain neutral conditions. 

Y. Kikuzono, S. Kagami, S. Naito, T. Onish, and K. Tamaru, Selective Hydrogenation of Carbon Monoxide on Palladium Catalysts, Faraday Discuss. Chem. Soc. 72, 135 (1982). 

Kimura M, Futamata M, Mukai R, Tamaru Y (2005) Pd-Catalyzed C3-selective Allylation of Indoles with Allyl Alcohols Promoted by Triethylborane. J Am Chem Soc 127 4592... 

Hallberg s group deliberately introduced y6-amino tethers for the /3-selective arylation of vinyl ethers. They further extended this system to chiral substrates for diastereoselec-tive arylation processes. Similar to their systems, Badone introduced /3-phosphino tethers for the /3-selective arylation of vinyl ethers. Tamaru has reported carbamate directing... 

Tamaru and coworkers [9] have reported an alternative method of realizing a selective Hy-abstraction without using silver salts. Allylic carbamates 8 can be transformed into the corresponding cinnamyl derivatives 10 by the Mizoroki-Heck arylation with iodobenzene (Figure 7.6). A six-membered chelate intermediate 9 has been proposed for the selective Hy-abstraction. 

The electronegativity of metal ion, i, was first proposed by Tanaka, Oaaki, and Tamaru (Shokubai, 6, 262 (1964)) the values were calculated by the equation z - (1 +Z) xo — (1), where Z and xo are the oxidation number of metal ion and the electronegativity of metal as element, respectively. Later, Tanaka and Ozaki revised the values by using xi - (1 + 2Z) xo — (2). Since xi from eq. (1) did not fit the data, Misono el al derived an independent equation of xi - xo + (E/n)ii — (3), where / is the n-th ionization potential, in order to explain the catalytic activity and selectivity of metal sulfates for butene isomerization. However, there is fairly good correlation between the revised x-, from eq. (2) and Xi from eq. (3). The electronegativity used here is from eq. (3). ... 

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