Hiroshi Yamataka

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Myositis ossificans circumscripta (or pseudomalignant osseous tumor of soft tissue) may be confused with malignant neoplasms if there is no clear history of trauma. Two cases are presented in which magnetic resonance imaging (MRI) clearly demonstrates disproportionally extensive abnormal signal intensity along the course of muscle fibers. Although the(More)
As a continuing theoretical study on the alpha-effect in the S(N)2 reactions at saturated carbon centers, 28 gas-phase reactions have been examined computationally by using the high-level G2(+) method. The reactions include: Nu(-)+CH(3)X-->CH(3)Nu+X(-) (X=F and Cl; Nu(-)=HO(-), HS(-), CH(3)O(-), Cl(-), Br(-), HOO(-), HSO(-), FO(-), ClO(-), BrO(-),(More)
The reactions of oximes to amides, known as the Beckmann rearrangement, may undergo fragmentation to form carbocations + nitriles when the migrating groups have reasonable stability as cations. The reactions of oxime sulfonates of 1-substituted-phenyl-2-propanone derivatives (7-X) and related substrates (8-X, 9a-X) in aqueous CH(3)CN gave both rearrangement(More)
Simulations for the Hydrolysis of the Methyl Diazonium Ion Makoto Sato,† Hiroshi Yamataka,*,† Yuto Komeiji,‡ Yuji Mochizuki,† Takeshi Ishikawa,† and Tatsuya Nakano§ Department of Chemistry, Rikkyo UniVersity, Toshima-ku, Tokyo 171-8501, Japan, National Institute of AdVanced Industrial Science and Technology, AIST Central 2, Tsukuba 305-8568, Japan, and(More)
The origin of enhanced reactivity of alpha-nucleophiles in SN2 reactions was examined on the basis of computational results at the high level G2(+) method for 22 gas-phase reactions: Nu- + RCl --> RNu + Cl- [R = Et and i-Pr; Nu- = HO-, CH3O-, HS-, Cl-, Br-, NH2O-, HOO-, FO-, HSO-, ClO-, and BrO-]. The results clearly indicate the existence of the(More)
A critical role is traditionally assigned to transition states (TSs) and minimum energy pathways, or intrinsic reaction coordinates (IRCs), in interpreting organic reactivity. Such an interpretation, however, ignores vibrational and kinetic energy effects of finite temperature. Recently it has been shown that reactions do not necessarily follow the(More)
Twenty open-chain mono-, di-, and trialkyl and aryl-N-substituted cyanomalonamides R2R1NCOCH(CN)CONHR3 were prepared. In solution, signals for both amide and a single enol are mostly observed, despite the potential for E and Z isomeric enols. The equilibrium (KEnol) values between the amides and the enols were determined in different solvents by NMR(More)
Fragment Molecular Orbital based-Molecular Dynamics (FMO-MD, Komeiji et al., Chem Phys Lett 2003, 372, 342) is an ab initio MD method suitable for large molecular systems. Here, FMO-MD was implemented to conduct full quantum simulations of chemical reactions in explicit solvation. Several FMO-MD simulations were performed for a sphere of water to find a(More)
The N(2) liberation from iminodiazonium ion (2-X) is a key step of the Schmidt rearrangement of ketones. Molecular orbital calculations showed that two concurrent reaction channels, syn-benzyl fragmentation and anti-Me rearrangement, exist for syn-2, whereas anti-2-X proceeds via a single TS. Substituent effect analyses of the reactions of syn-2-X gave(More)