Current Research Studies
Prostanoid biosyntheses with the aid of quantum mechanical calculations. PGIS and TXAS are in cytochrome P450 superfamily. (TXAS: Chem. Asian J. 2008, PGIS: Chem. Eur J. 2009 ) Role of water molecules in the proton-coupled electron transfer (PCET) process in an unusual cytochrome P450 caralyzed reaction (J. Mol. Graph. Model. accepted) NEW!.
We investigated the interaction of group 12 metal ions (Hg2+, Cd2+, Zn2+) with a cysteine/deprotonated cysteine molecule with DFT and high-level ab initio calculations. Water microsolvation approach is necessary to predict higher affinity of Hg2+ than Zn2+ with a cysteine molecule in aqueous solution. Unexpected results appeared in this theoretical studies. (Theor. Chem. Acc. 2011 )
Tungsten-mediated cycloaddition (Chem. Eur. J. 2009), Os-catalyzed hydroxylation (J. Am. Chem. Soc. 2012), Rh- and Pd- catalyzed C-CN bond activation reactions (Bull. Chem. Soc. Jpn, in press, and Dalton Trans 2014) NEW!
With aid of IMOMM studies, we are studying the origin of stereoselectivity of enantioselective and diastereoselective reactions. Recently, we found the Rh(I)-BINAP catalyzed hydrogenation with enamides goes through the major Rh(I)(BINAP)(enamide) complex with "lock-and-key" principle as opposed to the other Rh(I)-catalyzed hydrogenation. (Chem. Asian J. 2006)
Turquoselectivity of oxetene ring opening to afford unusual high selectivity of alkenes in the reaction of a lithium ynolate with carbonyl compounds. (Review: Synlett 2009; J. Am. Chem. Soc. 2002, Chem. Eur. J. 2006, Org. Lett. 2004, J. Am. Chem. Soc. 2009 , Synlett 2013, and so on)
In the [1,5]-sigmatropic hydrogen shift from 1,3-pentadiene, the primary kinetic isotope effects (kH/kD = 12.2 at 298 K) has been already determined for fourty years. Nevertheless, the reason has not been still clarified. With conventional HF and MP2 calculations with Born-Oppenheimer approximation, the KIE values are too small. We have had to use the semiclassical treatment for the tunneling corrections. Recently, with the aid of the MC_MO method developed by Prof. Tachikawa, which treats a hydrogen nuclei as a wavefunction, the KIE value is found to be much closer to the experimental values (8.28 at 298 K). (J. Phys. Chem. A. 2007)
We have examined the reaction mechanisms of several important organocuprate reactions (J. Am. Chem. Soc. 2000; Organometallics 2004; Angew. Chem. Int. Ed. 2005, and so on). Impotrance of multi-point hydrogen bonding interactions in Cu(I)-catalyzed enantioselective C-C bond formation (Chem. Eur. J. 2013)NEW!.