meso‐Thiaporphyrinoids Revisited: Missing of Sulfur by Small Metals

Facile synthesis of meso‐aryl‐substituted 5,15‐dithiaporphyrins and 10‐thiacorroles has been achieved by sulfidation of α,α′‐dichlorodipyrrin metal complexes with sodium sulfide in DMF. Thiacorrole metal complexes exhibit distinct aromaticity due to 18 π‐conjugation including the lone pair on sulfur, whereas dithiaporphyrins are nonaromatic judging from ¹H NMR spectra, X‐ray analysis, and absorption spectra. We have found that Ni^II and Al^III dithiaporphyrin complexes undergo smooth thermal sulfur extrusion reaction to give the corresponding thiacorrole complexes, whereas free base, Zn^II, Pd^II, and Pt^II dithiaporphyrin complexes did not exhibit the similar reactivity. The DFT calculations have elucidated a reaction pathway involving an episulfide intermediate, which can explain the markedly different reactivity among dithiaporphyrin metal complexes.     

Metal-free catalytic reduction of aldehydes,ketones,aldimines,and ketimines

<正>The metal-free combination of catalytic amounts of PPh_3,B(C_6F_5)_3,and PhSiH_3 can efficiently hydrosilylate aldehydes, ketones,aldimines and ketimines to afford the corresponding reduction products in good yields.     

Amino acids and peptides. LIV. Application of 2-adamantyl derivatives as protecting groups to the synthesis of peptide fragments related to Sulfolobus solifataricus ribonuclease. I.

The 2-adamantyloxycarbonyl group was employed for the protection of the epsilon-amino group of Lys and the hydroxyl group of Tyr, and the 2-adamantyl ester was employed for the protection of the beta-carboxyl group of Asp in order to construct eight peptide segments as building blocks for the preparation of peptide fragments related to the sequence of Sulfolobus solifataricus Ribonuclease. The usefulness of the above protecting groups developed in our laboratory was confirmed.     

An improved synthesis of butyl 4-[(4-amino-5-chloro-2-methoxybenzoyl)amino]-1-piperidineacetate (AU-224).

A new and facile route for the synthesis of the novel gastrointestinal prokinetic butyl 4-[(4-amino-5-chloro-2-methoxybenzoyl)amino]-1-piperidineacetate (1b), which exhibited potent gastro- and colon-prokinetic activities by oral administration without significant side effects, was established. The key intermediate, butyl 4-amino-1-piperidineacetate (16), was prepared from commercially available 4-amino-1-benzylpiperidine (2) in a high yield with four steps. Compound 1b was prepared by condensation of commercially available 4-amino-5-choloro-2-methoxybenzoic acid (7) with 16 in 84% yield. This improved synthetic route was appropriate for large-scale synthesis of 1b.     

Synthesis of a polyester macromonomer via the cobalt-catalyzed alternating copolymerization of propylene oxide and carbon monoxide

The alternating copolymerization of propylene oxide and carbon monoxide was investigated with cobalt complexes. The NaCo(CO)₄/amine catalyst system selectively yielded oligo(3-hydroxybutyrate)s bearing a polymerizable crotonate end group, whereas the use of Co₂(CO)₈ as a cobalt source resulted in a smaller concentration of the crotonate end group and a high degree of polymerization. The high selectivity for the oligoesters with the crotonate end group with the NaCo(CO)₄/amine system was attributed to its more basic reaction condition. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4666–4670, 2004     

Strong-symmetry-breaking limit of SU(3) Skyrme model and bound-kaon approach to strangeness

The semi-leptonic weak decays of hyperons are investigated in the Skyrme model. The vector currents for strangeness-changing processes are shown to have a very similar structure in the strong-symmetry-breaking limit in the SU(3) collective-coordinate method, proposed by Yabu and Ando, with those in the bound-kaon approach to strangeness by Callan and Klebanov. It is also shown that the quite differentN _c dependence between them becomes also to coincide with each other in the limit.Dedicated to Prof. Erich Schmid on the occasion of his 60th birthday     

Ladder type supramolecular assembly and gas adsorption profile under reduced pressure based on hydrogen bonded m-tetraphenyl derivative of anthracene

We report a guest adduct X-ray structures and gas adsorption capability of 9,10-bis(4″,4-dihydroxyl-m-terphen-5″-yl)anthracene, which is an analogue of anthracene-bis(resorcinol) derivative reported by Aoyama et al. The gas adsorption capability is double scale of guest inclusion than that of anthracene-bis(resorcinol) derivative.