Kazunori Odashima

Catalytic enantioselective intermolecular [2 + 2 + 2] cycloaddition of an alkene and two alkynesElectronic supplementary information (ESI) available: experimental and spectroscopic data. See http://www.rsc.org/suppdata/cc/b2/b208313b/

A catalytic enantioselective intermolecular [2 + 2 + 2] cycloaddition of one molecule of alkene (enone) and two molecules of alkyne was developed in the presence of a nickel complex modified by chiral monodentate oxazoline ligands, which have not previously been used as chiral ligands for transition metals in asymmetric catalysts, and an aluminium phenoxide.

[48] Bacteriorhodopsin: Fourier transform infrared methods for studies of protonation of carboxyl groups

Publisher Summary Bacteriorhodopsin (bR) is the protein found in the purple membrane of the bacterium, Halobacterium halobium . This chapter describes the fourier transform infrared (FTIR) methods used for the studies of the protonation of carboxyl groups. To investigate the role of carboxyls in the photocycle of bR, comparative FTIR difference studies on native bR and bR obtained from bacteria grown on isotopically labeled [ 13 C] aspartic and/or glutamic acids [(4- 13 C) aspartic acid or (5- 13 C) glutamic acid bR]. A bR film is prepared by drying purple membrane on an infrared (IR) transmitting window and sealing with an IR- and visible light-transmitting window. The FTIR difference spectra yield the vibrational modes in the chromophore and apoprotein that differ between bR and the photocycle intermediates. Differences between native and isotopically labeled FTIR spectra reflect the vibrational modes in the carboxylic amino acids that change in the bR photocycle. These changes in vibrational mode frequencies can then be interpreted in terms of changes in the environment or protonation of the particular carboxylic amino acid between bR and the photocycle intermediates.

Studies with retinal pigments: modified point charge model for bacteriorhodopsin and difference FTIR (Fourier transform infrared) studies

Incorporation of dihydroretinals into the sensory rhodopsin SR and bacteriorhodopsin bR has led to a modified version of the external point-charge model for bR proposed in 1979. Difference Fourier transform infrared studies of native bR and bR analogs cultured on media containing isotopes of amino acids have shown some of the amino acids which undergo environmental changes or deprotonation/protonation during the bR photocycle leading to proton translocation. The proton pumping abilities of some bR analogs are compared. A visual pigment analog containing a nine-membered retinal has been prepared and studies such as FTIR are under study.

Nickel-catalyzed coupling of allyl chlorides and enynes

The Ni-catalyzed coupling of allyl chlorides and enynes has been developed; the cyclization of enynes was triggered by the addition of pi-allylnickel species to the alkyne part, followed by the incorporation of the alkene part.

Chemo- and regioselective cyclotrimerization of monoynes catalyzed by a nickel(0) and zinc(II) phenoxide system

A binary metal system of nickel(0) and zinc(II) phenoxide catalyzed the chemo- and regioselective cyclotrimerization of monoynes.