Hideki Yorimitsu

Triethylborane-induced atom-transfer radical cyclization of iodo acetals and iodoacetates in water is described. Radical cyclization of iodo acetal proceeded smoothly both in aqueous methanol and in water. Atom-transfer radical cyclization of allyl iodoacetate (3a) is much more efficient in water than in benzene or hexane. For instance, treatment of 3a with triethylborane in benzene or hexane at room temperature did not yield the desired lactone. In contrast, 3a cyclized much more smoothly in wa

Copper complements palladium as a catalyst of asymmetric allylic substitutions (see scheme). Palladium catalysis requires soft nucleophiles to ensure high stereo- and regioselectivity, whereas hard nucleophiles such as Grignard and organozinc reagents may be used under copper catalysis. Vast progress during the last decade reveals the promising future of copper catalysis in this asymmetric transformation.

Two new palladium-catalyzed reactions of aromatic sulfur compounds enabled the conversion of dibenzothiophenes into triphenylenes in four steps. This transformation of one aromatic framework into another consists of 1) 4-chlorobutylation of the dibenzothiophene to form the corresponding sulfonium salt, 2) palladium-catalyzed arylative ring opening of the sulfonium salt with a sodium tetraarylborate, 3) an intramolecular S(N)2 reaction to form a teraryl sulfonium salt, and 4) palladium-catalyzed

A new class of Pummerer chemistry has emerged as a powerful tool in organic synthesis. The new technology consists of a beautiful cascade of an interrupted Pummerer reaction and the subsequent [3,3] sigmatropic rearrangement. The interrupted Pummerer reactions of alkenyl or aryl sulfoxides with unsaturated nucleophiles such as allylic silanes, ketones, and phenols provide sulfonium intermediates, which are ready to undergo smooth charge-accelerated [3,3] sigmatropic rearrangement with excellent

ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTTriethylborane-Mediated Atom Transfer Radical Cyclization Reaction in WaterHideki Yorimitsu, Tomoaki Nakamura, Hiroshi Shinokubo, and Koichiro OshimaView Author Information Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Sakyo-ku, Yoshida, Kyoto 606-8501, Japan Cite this: J. Org. Chem. 1998, 63, 23, 8604–8605Publication Date (Web):October 22, 1998Publication History Received31 August 1998Published online22 October 1998P

A mixture of ethyl bromoacetate and 1-octene was treated with triethylborane in water at ambient temperature to provide ethyl 4-bromodecanoate in good yield. The bromine atom-transfer radical addition in benzene was not satisfactory. The addition proceeded smoothly in polar solvents such as DMF and DMSO, protic solvents such as 2,2,2-trifluoroethanol and 1,1,1,3,3,3-hexafluoro-2-propanol, and aqueous media. Ab initio calculations were conducted to reveal the origin of the solvent effect of water

Making a break for it: Treatment of 2-(2-pyridyl)ethanol derivatives with aryl chlorides in the presence of a palladium catalyst results in the transfer of the pyridylmethyl moiety of the alcohol to yield the corresponding (2-pyridylmethyl)arene. The reaction proceeds by chelation-assisted cleavage of an CC bond (see scheme) followed by formation of a carbon–carbon bond.

Abstract Without suffering from β-elimination, cobalt complexes allow cross-coupling reactions of alkyl halides with Grignard reagents. A combination of a cobalt complex and trimethylsilylmethyl Grignard reagent effects Mizoroki-Heck-type reaction of alkyl halide with styrene, which conventional palladium catalysts have never made possible. Cobalt exhibits intriguing catalytic activities on hydrophosphination and allylzincation of alkynes. Silylmethylcobalt reagent is a powerful tool for the syn

Cat. in the bag: The pictured copper complex can promote CC bond cleavage through retro-allylation of homoallyl alcohols to form allylcopper species. This process is applicable to catalytic allylation of aldehydes and imines with homoallyl alcohols. The method has also been extended to regioselective allenylation and propargylation of imines. Detailed facts of importance to specialist readers are published as ”Supporting Information”. Such documents are peer-reviewed, but not copy-edited or typ

Dibenzothiophene dioxides, which are readily prepared through oxidation of the parent dibenzothiophenes, undergo nucleophilic aromatic substitution with anilines intermolecularly and then intramolecularly to yield the corresponding carbazoles in a single operation. The "aromatic metamorphosis" of dibenzothiophenes into carbazoles does not require any heavy metals. This strategy is also applicable to the synthesis of indoles. Since electron-deficient thiaarene dioxides exhibit interesting reactiv

After the 20-year dormant period since Liebeskind's seminal report, triorganosulfonium salts have now proved to be reliably useful surrogates of or complement to organic halides in a variety of transition-metal-catalyzed transformations. By necessity, my group developed Suzuki-Miyaura ring-opening arylation of sulfonium salts of dibenzothiophenes with tetraarylborates and Pd-catalyzed intramolecular C-H/C-S coupling. Following this starting point and experiencing the decent reactivity of sulfoni

This account focuses on the discovery and the rationalization of solvent effects, especially those of water, on synthetically useful radical reactions. Noteworthy advantages were observed during the course of our study on radical reactions in aqueous media. The established advantages of water as a solvent for radical reactions are (1) facile room-temperature atom transfer radical cyclization of allyl iodoacetate, (2) highly efficient construction of medium and large rings via radical cyclization

Aromatic skeletons are generally regarded as being uncleavable because of their aromatic stabilization energy. Compared to exocyclic functionalizations of aromatic compounds, much less attention has been paid to substitutions of endocyclic atoms in aromatic cores through partial disassembly of the cyclic skeletons and subsequent ring reconstruction. In this Feature Article, we describe our endeavours to establish "aromatic metamorphosis", where general aromatic compounds such as dibenzothiophene