Stereo-regulated synthesis of peptides containing a β-trifluoromethyl-β-amino acid

For the chemical conversions of a β-trifluoromethyl-β-amino acid ((S)-4,4,4-trifluoro-3-aminobutyric acid, 1), such as the N-terminus protection with benzyloxycarbonyl or tert-butoxycarbonyl group, the C-terminus protection with benzyl or tert-butyl group, and peptide elongation at the both termini, highly practical protocols were established. Through these conversions, the stereochemistry of 1 and/or its condensation counterpart was maintained. Because the protocols developed here are indispensable for the application of 1 in peptide engineering, they would expand the utility of 1 and its derivatives.     

Direct synthesis of highly fused perimidines by copper(I)-catalyzed hydroamination of 2-ethynylbenzaldehydes

A novel synthesis of highly fused perimidine derivatives was achieved in two steps from 2-alkynylbenzaldehydes. Copper-catalyzed annulation of 2-[(2-bromophenyl)ethynyl]benzaldehydes with 1,8-diaminonaphthalene produced dihydroisoquinolino[2,1-a]perimidines bearing a 2-bromophenyl group. Subsequent palladium-catalyzed C-H arylation provided dibenzo[1,2:7,8]quinolizino[3,4,5,6-kla]perimidine derivatives in moderate to good yields.     

Gold-catalyzed three-component annulation: efficient synthesis of highly functionalized dihydropyrazoles from alkynes, hydrazines, and aldehydes or ketones

Polysubstituted dihydropyrazoles were directly obtained by a gold-catalyzed three-component annulation. This reaction consists of a Mannich-type coupling of alkynes with N,N'-disubstituted hydrazines and aldehydes/ketones followed by intramolecular hydroamination. Cascade cyclization using 1,2-dialkynylbenzene derivatives as the alkyne component was also performed producing fused tricyclic dihydropyrazoles in good yields.     

Crystallization behavior of bisphenol A polycarbonate with a simple vacuum process

The crystallization behavior of an amorphous polymer, bisphenol A polycarbonate (BAPC), was evaluated. BAPC was crystallized by exposure to diphenylpropane, a component of BAPC, by vapor transportation methods. Furthermore, the surface of BAPC was also crystallized by this method. Crystallized BAPC was employed as a novel simple storage medium, and bit patterns were recorded on its surface by laser irradiation. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 2307–2313, 2005     

Design and synthesis of all diastereomers of cyclic pseudo-dipeptides as mimics of cyclic CXCR4 pentapeptide antagonists

The four diastereomers of 2,5-bis[(3-guanidino)propyl]-1-[3-(4-hydroxyphenyl)propionyl]-7-(2-naphthylacetyl)-1,4,7-triazacycloundec-9-en-3-one (-) and of 2,5-bis[(3-guanidino)propyl]-1-(4-hydroxyphenylacetyl)-7-(2-naphthylacetyl)-1,4,7-triazacycloundec-9-en-3-one (-) were synthesized by a divergent methodology from l- and D-glutamic acids. The 11-membered ring core was made by ring closing metathesis of linear bis(allylamines), and the guanidyl functions were introduced by a simultaneous double Mitsunobu reaction using bis(Boc)guanidine. These compounds were designed to mimic cyclic pentapeptide FC131 (c[Gly-D-Tyr-Arg-Arg-Nal]).     

Orientation of Rod-Shape Molecule, 2,2′-Bis[4-(Trifluoromethyl)Phenyl]-5,5′-Bithiazole in Films Deposited in a Vacuum on Oriented α-Sexithiophene Films

We demonstrated orientation control of n-type rod-shape, 2,2′-Bis[4-(trifluoromethyl)phenyl]-5,5′-bithiazole (BTMPB) molecules when deposited on the in-plane oriented polythiophene (PT) and α-sexithiophene (6T)/PT films in vacuum. The results showed that the π-π stacking direction of BTMPB molecules on the PT and 6T/PT films is perpendicular to the substrate plane. In addition, a molecular long axis of BTMPB oriented parallel to the friction direction of the PT. Moreover, in-plane orientation of BTMPB was more enhanced by in-plane oriented 6T molecules than in-plane oriented PT underneath. On the other hand, the molecular long axis of BTMPB deposited on the substrates stood on the substrates.