[reaction: see text] Introduction of an electron-withdrawing group on the aromatic ring of N-methylacetanilide decreased the ratio of the cis conformer, and the ratio correlates well with the Hammett sigma values of the substituents. These steric properties can be applied to achieve amide conformational switching by protonation at the aromatic substituent of 4-[bis(dimethylamino)]-N-methylacetanilide or N-[p-(dimethylamino)phenyl]-N-phenylacetamide.

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Rotacatenanes were synthesized by the catalytic reaction using a macrocyclic phenanthroline-CuI complex followed by the installation of another ring by the template method. In this approach, the size of the ring component of the rotaxane turns out to be a very important factor for the synthesis of rotacatenanes.

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Here, aiming to adopt the phenyl–perfluorophenyl interaction to regulate molecular alignment and arrangement for crystal engineering, we examined and compared in detail the crystal structures of N,N′-diphenylurea compounds 1–6. We found that phenyl–perfluorophenyl interaction greatly influenced the intermolecular arrangement in the crystal, and we were able to prepare a cocrystal of 1 and 2, in which the molecules were alternately arranged under the control of the phenyl–perfluorophenyl interaction. This arrangement was driven by the asymmetric geometry of the hydrogen bonds in the cocrystal (1·2), in which 2, bearing two perfluorophenyl groups, worked as a better hydrogen bond donor. In contrast, NH connected to the phenyl group in 3 proved to be a better hydrogen bond donor due to the intramolecular resonance effect. N,N′-Dimethylated derivatives, 4–6, existed in cis-cis form in the crystal. Antiparallel carbonyl–carbonyl arrangements were observed in 4 and 6, while an unexpected carbonyl–perfluorophenyl interaction was observed in the crystal of 5. These findings will be helpful in the design of diphenylurea-based functional molecules, especially for solid-state application.

Alpha-glucosidase inhibitors with a phthalimide skeleton were prepared. Structure-activity relationship studies indicated a critical role for the hydrophobicity of the substituent at the nitrogen atom of the phthalimide skeleton. Introduction of electron-withdrawing groups, including a nitro group and chlorine, influenced the activity. Optimization studies led us to design 4,5,6,7-tetrachloro-N-phenylphthalimide (CPOP) and its N-phenylalkyl derivatives. CP0P and 4,5,6,7-tetrachloro-N-(4-phenylbutyl)phthalimide (CP4P) proved to be more potent alpha-glucosidase inhibitors than the known inhibitor 1-deoxynojirimycin.

The chemistry of transition-metal complexes containing N-heterocyclic carbenes (NHCs) has been extensively studied, and a large number of compounds have been reported. Among various metal complexes, the Ag-NHC complexes turned out to be very unique, since they are fluxional molecules and also efficient carbene-transferring reagents. The structures of these complexes were also interesting, and many examples have been reported in the literature. 1 The compounds could be readily prepared by the reaction of the imidazolium salt with Ag 2 O, and it is not necessary to isolate NHC, which is a less stable species. Interestingly, few 1:1 complexes were reported, 2 while a series of 2:1 (Ag 2 (bis-NHC)) complexes 3,4 and 2:2 (Ag 2 (bis-NHC) 2 ) complexes 5-7 were characterized. Even cyclic bisimidazolium salts reacted with Ag 2 O to give interesting 2:2 complexes. 8 Many of these Ag-NHC complexes were known as good carbenetransfer agents, and various metal-NHC complexes have been synthesized. Among the complexes, the Pd-NHC complexes 9 have been extensively studied since the complexes are potentially useful catalysts for organic synthesis. In contrast to the corresponding Ag-NHC complexes, a limited number of dinuclear Pd complexes have been reported in the literature. 10 We have been interested in the chemistry of metal-bis-NHC and metal-NHC-oxazoline complexes and synthesized some Pd complexes with unique structures. 11 In this paper we report the synthesis and structure of new dinuclear silver and palladium complexes that are connected with 2,7-dimethylnaphthalenebridged bis-NHC ligands. 11 The catalytic activities of the Pd complexes were also examined.

A novel series of small molecule nonpeptide aminopeptidase N (APN) inhibitors with a N-phenylphthalimide or N-phenylhomophthalimide skeleton were prepared. Evaluation of their protease inhibitory activities revealed that (i) some N-phenylphthalimide analogs are potent APN inhibitors, but they are also inhibitors of another protease, dipeptidylpeptidase IV (DPP-IV), and (ii) some N-phenylhomophthalimide analogs, including 2-(2,6-diethylphenyl)-1,2,3,4-tetrahydroisoquinoline-1,3-dione (PIQ-22), are potent and specific inhibitors of APN without DPP-IV-inhibitory activity. The structure-activity relationship studies of N-phenylphthalimides and N-phenylhomophthalimides are reviewed. PIQ-22 showed potent tumor-cell invasion-inhibitory activity.