Positive muons in [Co(NH3)6]Cl3 and [Co(ND3)6]Cl3

We have carried out SR experiments on [Co(NH₃)₆]Cl₃ and [Co(ND₃)₆]Cl₃. At 293 K, all the muons implanted into the complexes were in the diamagnetic state. The observed Gaussian-type muon spin relaxation function proved that the internal magnetic field was caused by nuclear dipole moments of the atoms in the complexes. In addition, another exponential-type muon spin relaxation function was observed in [Co(ND₃)₆]Cl₃ below 50 K.     

Generalized Aluthge transformation on -hyponormal operators

We shall introduce a generalized Aluthge transformation on -
hyponormal operators and also, by using the Furuta inequality, we shall give several properties on this generalized Aluthge transformation as further extensions of some results of Aluthge.

     

New methods and reagents in organic synthesis. 56. Total syntheses of patellamides B and C,cytotoxic cyclic peptides from a tunicate 2. Their real structures have been determined by their syntheses.

The proposed structures of patellamides B and C, cytotoxic lipophilic cyclic peptides from a marine tunicate, have been revised on the basis of the spectral data of their partial hydrolysates, and their revised structures have been synthetically confirmed by the use of diphenyl phosphorazidate(DPPA) and diethyl phosphorocyanidate(DEPC).     

Diethyl phosphorocyanidated (DEPC). A novel reagent for the classical Strecker's α-amino nitrile synthesis

Diethyl phosphorocyanidate (DEPC) can be efficiently used for the synthesis of α-amino nitriles from carbonyl compounds and amines. The reaction may be called a modified Strecker synthesis.     

Reactivity control of an allylsilane bearing a 2-(phenylazo)phenyl group by photoswitching of the coordination number of silicon

Photoswitching of the coordination number of silicon between four and five in allyldifluoro[2-(phenylazo)phenyl]silane, which was confirmed by X-ray analysis and multinuclear NMR spectroscopy, caused multistep reactions to proceed or stop, yielding tetrafluoro[2-(1-allyl-2-phenylhydrazino)phenyl]silicate without altering other reaction conditions.     

Intramolecular tandem Michael-type addition/aldol cyclization induced by TiCl(4)-R(4)NX combinations

[reaction: see text] Treatment of formyl alpha,beta-enones with a TiCl(4)-R(4)NX combination induces an intramolecular aldol cyclization to furnish 2-acyl-3-halocyclohexanol with three controlled consecutive stereogenic centers. The reaction of bis-alpha,beta-enones with the combination provides cyclic diketones with high stereoselectivity via an intramolecular Michael addition reaction.     

Development of calixarene-based host molecules for peptides in aqueous media

We synthesized a peptidocalix[4]arene library consisting of 1000 members that was suitable for peptide recognition in aqueous media. Some peptidocalix[4]arenes in the library were host molecules for guest peptides. Electrostatic interaction between the host and guest molecules was the most important factor for binding in aqueous media.