Shinsuke Komagawa

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Different homoleptic and heteroleptic lithium-zinc combinations were prepared, and structural elements obtained on the basis of NMR spectroscopic experiments and DFT calculations. In light of their ability to metalate anisole, pathways were proposed to justify the synergy observed for some mixtures. The best basic mixtures were obtained either by combining(More)
Homoleptic lithium tri- and tetraalkyl zincates were reacted with a set of bromopyridines. Efficient and chemoselective bromine-metal exchanges were realized at room temperature with a substoichiometric amount of nBu(4)ZnLi(2)·TMEDA reagent (1/3 equiv; TMEDA=N,N,N',N'-tetramethylethylenediamine). This reactivity contrasted with that of tBu(4)ZnLi(2)·TMEDA,(More)
The [3 + 2 + 2] cocyclization of ethyl cyclopropylideneacetate (1a) and terminal alkynes (2) proceeded smoothly in the presence of 10 mol % "Ni(PPh3)2", which was prepared in situ from Ni(cod)2 and PPh3. The high reactivity of 1a, which was induced by the introduction of an electron-withdrawing group, is very important for the progress of this reaction. The(More)
About 40 years have passed since methylene dizinc reagent was discovered as a substitute for Wittig reagent. Density functional theory (DFT) calculations have been performed to understand the reaction pathways of methylenation of carbonyl compounds with bis(iodozincio)methane. The present computational/theoretical study concluded that the methylenation(More)
Cross-coupling is a fundamental reaction in the synthesis of functional molecules, and has been widely applied, for example, to phenols, anilines, alcohols, amines and their derivatives. Here we report the Ni-catalysed Stille cross-coupling reaction of quaternary ammonium salts via C-N bond cleavage. Aryl/alkyl-trimethylammonium salts [Ar/R-NMe3](+) react(More)
Lithium cadmates bearing different ligands were compared with efficient (TMP)(3)CdLi (TMP = 2,2,6,6-tetramethylpiperidino) for their ability to deprotometalate anisole. The generated arylcadmates were evidenced using I(2). The results show that it is possible to replace only one of the TMP (with a piperidino, a diisopropylamino, a butyl, or a sec-butyl)(More)
1,4-Addition of bis(iodozincio)methane to simple α,β-unsaturated ketones does not proceed well; the reaction is slightly endothermic according to DFT calculations. In the presence of chlorotrimethylsilane, the reaction proceeded efficiently to afford a silyl enol ether of β-zinciomethyl ketone. The C--Zn bond of the silyl enol ether could be used in a(More)
TMPLi (TMP=2,2,6,6-tetramethylpiperidide) reacts with Cu(I) salts in the presence of Et2O to give the dimers [{(TMP)2Cu(X)Li2 (OEt2)}2] (X=CN, halide). In contrast, the use of DMPLi (DMP=cis-2,6-dimethylpiperidide) gives an unprecedented structural motif; [{(DMP)2CuLi(OEt2)}2LiX] (X=halide). This formulation suggests a hitherto unexplored route to the in(More)