The development of highly efficient amide bond forming methods which are devoid of side reactions, including epimerization, is important, and such a method is described herein and is based on the concept of rapid and strong activation of carboxylic acids. Various carboxylic acids are rapidly (0.5 s) converted into highly active species, derived from the inexpensive and less-toxic solid triphosgene, and then rapidly (4.3 s) reacted with various amines to afford the desired peptides in high yields (74 %–quant.) without significant epimerization (≤3 %). Our process can be carried out at ambient temperature, and only CO2 and HCl salts of diisopropylethyl amine are generated. In the long history of peptide synthesis, a significant number of active coupling reagents have been abandoned because the highly active electrophilic species generated are usually susceptible to side reactions such as epimerization. The concept presented herein should renew interest in the use of these reagents.

A holographic technique is applied for digital watermarking by a computer. A digital-watermark image to be hidden is phase modulated in a random fashion, and its Fourier-transformed hologram is superposed on a content image. The watermark is reconstructed by means of a holographic-reconstruction technique from the bit-map image that hides it. In the study the processes of constructing and reconstructing a digital hologram are described on the basis of the theory of Fourier optics. The conditions for superposing the hologram onto the content images are investigated in detail. The validity of the present method is verified by changing the weighting of the hologram relative to that of the content image. The effect of image size is also discussed with respect to reconstruction of the watermark, and it is shown that watermark information in a form of a diffuse-type Fourier-transform hologram cannot be removed by cutting it out of the host image.

Feglymycin is a naturally occurring, anti-HIV and antimicrobial 13-mer peptide that includes highly racemizable 3,5-dihydroxyphenylglycines (Dpgs). Here we describe the total synthesis of feglymycin based on a linear/convergent hybrid approach. Our originally developed micro-flow amide bond formation enabled highly racemizable peptide chain elongation based on a linear approach that was previously considered impossible. Our developed approach will enable the practical preparation of biologically active oligopeptides that contain highly racemizable amino acids, which are attractive drug candidates.

An efficient, two-stage, continuous-flow synthesis of 1α,25-(OH)(2)-vitamin D(3) (activated vitamin D(3)) and its analogues was achieved. The developed method afforded the desired products in satisfactory yields using a high-intensity and economical light source, i.e., a high-pressure mercury lamp. In addition, our method required neither intermediate purification nor high-dilution conditions.