Scalable Total Syntheses and Structure–Activity Relationships of Haouamines A,B, and Their Derivatives as Stable Formate Salts

Haouamines A, B, and their derivatives were synthesized via Suzuki–Miyaura coupling and three key cyclization reactions as follows: the newly developed palladium(0)-catalyzed arylative cyclization of phenylalanine-derived alkyne–aldehydes with 2-bromoarylboronic acid (an “anti-Wacker”-type cyclization); BF₃ ⋅ OEt₂-promoted Friedel–Crafts-type cyclization of symmetrical electron-rich aromatic rings adjacent to a tertiary allylic alcohol leading to the indeno-tetrahydropyridine skeleton; and (cyanomethyl)trimethylphosphonium iodide-mediated macrocyclization of amino alcohols to afford aza-paracyclophane precursors. The palladium-catalyzed reduction of mono- and di-triflate intermediates in the later stages enabled the alteration of both the position and number of hydroxyl groups on the C-ring. The instability of haouamine B was dramatically improved by salt formation with formic acid. An unambiguous evaluation of the cytotoxicity of the prepared haouamine derivative formates with and without hydroxyl groups at different positions on the C-ring indicated that the catechol structure in haouamine B produced weak cytotoxicity.     

Isolation of a new indoxyl alkaloid,Amoenamide B,from Aspergillus amoenus NRRL 35600: Biosynthetic implications and correction of the structure of Speramide B

A new prenylated indoxyl alkaloid, Amoenamide B (1), was isolated from Aspergillus amoenus NRRL 35600 along with Asperochramide A (2). Although many prenylated oxindole alkaloids, containing bicyclo[2.2.2]diazaoctane cores, have been isolated from the fungus of the genera Aspergillus and Penicillium to date, 1 is the fourth compound with the indoxyl unit containing the cores. During the structure elucidation of 1, we found that the planar structure matched to that of Speramide A (3), isolated from A. ochraceus KM007, but the reported structure of 3 was incorrect and turned out to be that of Taichunamide H (4), recently isolated from A. versicolor HDN11-84.     

Dissolution kinetics of K-alum crystals as judged from the measurements of surface undersaturations

The normal dissolution rates, the slopes and the average velocities of dissolution steps of etch pits on the (111) face of a K-alum crystal, originating from dislocations with Burgers vector 110, were measured in relation to the surface undersaturations. From the mutual relations, it was shown that the dissolution was controlled by both diffusion and surface kinetic processes, although the contribution of the latter process was smaller than in the case of growth. It was also demonstrated that the normal dissolution rate was always larger than the growth rate. This is attributed to the fact that the slopes of growth hillocks are invariably smaller than those of etch pits.     

Direct construction of bicyclic heterocycles by palladium-catalyzed domino cyclization of propargyl bromides

The palladium-catalyzed domino cyclization of propargyl bromides having two nucleophilic functional groups is described. Treatment of 1,7-diamino-5-bromohept-3-yne derivatives with catalytic Pd(PPh3)4 in the presence of NaH in MeOH gives the 2,7-diazabicyclo[4.3.0]non-5-enes in good yields. Interestingly, the regioselectivity of the reaction is completely controlled by the relative reactivity of the amine functional groups, irrespective of the position of the nucleophiles. The malonate derivative also undergoes domino cyclization to produce a hexahydroindole derivative.     

Mean dimension of $${\mathbb{Z}^k}$$-actions

Mean dimension is a topological invariant for dynamical systems that is meaningful for systems with infinite dimension and infinite entropy. Given a \({\mathbb{Z}^k}\)-action on a compact metric space X, we study the following three problems closely related to mean dimension.

1. (1)
   When is X isomorphic to the inverse limit of finite entropy systems?
    
2. (2)
   Suppose the topological entropy \({h_{\rm top}(X)}\) is infinite. How much topological entropy can be detected if one considers X only up to a given level of accuracy? How fast does this amount of entropy grow as the level of resolution becomes finer and finer?
    
3. (3)
   When can we embed X into the \({\mathbb{Z}^k}\)-shift on the infinite dimensional cube \({([0,1]^D)^{\mathbb{Z}^k}}\)?
    

These were investigated for \({\mathbb{Z}}\)-actions in Lindenstrauss (Inst Hautes Études Sci Publ Math 89:227–262, 1999), but the generalization to \({\mathbb{Z}^k}\) remained an open problem. When X has the marker property, in particular when X has a completely aperiodic minimal factor, we completely solve (1) and a natural interpretation of (2), and give a reasonably satisfactory answer to (3).A key ingredient is a new method to continuously partition every orbit into good pieces.     

Revised model core potentials of s-block elements

We developed new model core potentials (MCPs) for s-block elements from Na to Ra, in which the outer core (n-1)s and (n-1)p electrons are treated explicitly together with the ns electrons. By adding suitable correlating functions, we demonstrated that the present MCP basis sets show excellent performance in describing the electronic structures of atoms and molecules, bringing about accurate ionization potentials of atoms and very good spectroscopic constants of ionic and covalent molecules. The results obtained with the new MCPs are very close to the ones obtained using the all-electron correlation consistent basis sets of Dunning.     

Dynamic processes in endocytic transformation of a raft-exhibiting giant liposome

The dynamic response of a raft-exhibiting giant liposome to external stimuli, such as the addition of Triton X-100 or osmotic stress, was studied. We observed that daughter vesicles are generated inside of the liposome through endocytic budding. It was found that the budding to generate daughter vesicles is classified into two different routes, simple budding through the invagination of a whole raft and budding from the boundary of a raft accompanied by waving motion. Smaller rafts show a preference for simple budding, whereas large rafts mainly adopt the other process. We discuss the mechanism of this difference in terms of the kinetic pathway of internalization by considering the line energy and bending energy of the membrane.     

Imaging of chemical reactivity and buckled dimers on Si(100)2×1 reconstructed surface with noncontact AFM

We have investigated the force interactions between the Si tip and the Si(100)2×1 reconstructed surface in the noncontact atomic-force microscopy (AFM) measurement. We observed two types of frequency shift curves without and with discontinuity, similar to the Si(111)7×7 surface. The image contrast changes drastically whether the frequency shift curve shows discontinuity or not. In the case of the frequency shift curves without discontinuity, the noncontact AFM images almost reflect the surface topography including dimers and adsorbates. In the case of the frequency shift curves with discontinuity, they reflect strongly the chemical reactivity of surface. Furthermore, in the case of the frequency shift curves without discontinuity, for the first time, the stabilize-buckling of dimers induced by a defect can be observed. This suggests that the force interactions during the noncontact AFM measurement hardly influence the surface dynamics.