Synthetic studies on psiguadial B: Construction of bicyclo[4.3.1]decane skeleton via double cyclization reaction of alkyne dicobalt complex

A new method for constructing the polycyclic skeleton of psiguadial B (1), a meroterpenoid isolated from an evergreen shrub of Myrtaceae, was developed. The terpenoid substructure of 1 was constructed on the basis of a cascade double cyclization reaction of an alkyne dicobalt complex, which afforded the bicyclo[4.3.1]decane derivative having a benzyl group with the correct configuration. The substituted aromatic ring was introduced to the bridgehead position of the intermediate, and bromination under radical conditions followed by intramolecular cyclization reaction resulted in formation of the benzopyran moiety in a stereoselective manner.     

Stereoselective synthesis of the right-hand segment of tubiferal A

Tubiferal A, a triterpenoid isolated from myxomycete Tubifera dimorphotheca, exhibits a reversal effect of vincristine (VCR) resistance against VCR-resistant KB cell lines. The compound possesses a complex structure involving the 6-7-6-5 polycyclic carbon framework with various functional groups. The stereoselective synthesis of the right-hand segment of tubiferal A was achieved on the basis of the cyclopentene annulation method and the semi-pinacol rearrangement reaction of an epoxy alcohol for constructing the trans-fused 6-5 bicyclic skeleton possessing two quaternary carbon atoms at the angular positions.     

Formal [6+4] cycloaddition of a dicobalt acetylene complex with furan derivatives

An efficient method for constructing a 10-membered carbocycle with an oxygen bridge has been developed on the basis of a formal [6+4] cycloaddition reaction. Under the influence of EtAlCl₂, a dicobalt hexacarbonyl acetylene complex possessing a benzoyloxy group and an allylsilane moiety reacted with furan to give a 11-oxabicyclo[6.2.1]undec-9-ene derivative. On treatment with iodine, the cycloadduct underwent decomplexation followed by rearrangement of the oxygen bridge to afford a 11-oxabicyclo[5.3.1]undeca-1,5-diene derivative.     

Carbon-Carbon Bond Formation Using Alkenylsulfides

Highly stereoselective C-C bond forming reactions were developed on the basis of nucleophilic addition of alkenylsulfides to aldehydes, imines, and α,β-unsaturated carbonyl compounds.     

Simulation of micro/nanometer-scale self-organized lightwave network (SOLNET) using the finite difference time domain method

A simulator for self-organized lightwave network (SOLNET) is developed. The simulator is based on the finite difference time domain method. SOLNET enables us to construct self-aligned coupling waveguides between misaligned micro/nanometer-scale optical devices by self-focusing, which arises from an increase in refractive index induced by write beams in photo-refractive materials. The SOLNET simulator reveals that an L-shaped nanometer-scale optical waveguide of SOLNET is grown from a 0.5-μm-wide optical waveguide when write beams are introduced from the optical waveguide into photo-refractive materials, where a wavelength filter is embedded. The SOLNET simulator also reproduces coupling path construction between a 2-μm-wide optical waveguide and a 0.5-μm-wide optical waveguide having a wavelength filter on the core edge. The optical waveguides are placed with misalignment of 0.5-μm offset. By introducing write beams from the 2-μm-wide optical waveguide, the incident write beams and reflected write beams from the wavelength filter merge into one optical waveguide in the photo-refractive materials, constructing a self-aligned coupling waveguide.     

Stability and sensitivity analysis in multiobjective nonlinear programming

In this paper some results on stability and sensitivity analysis in multiobjective nonlinear programming are surveyed. Given a family of parametrized multiobjective programming problems, the perturbation map is defined as the set-valued map which associates to each parameter value the set of minimal points of the perturbed feasible set with respect to an ordering convex cone. The behavior of the perturbation map is analyzed both qualitatively and quantitatively. First, some sufficient conditions which guarantee the upper and lower semicontinuity of the perturbation map are provided. The contingent derivatives of the perturbation map are also studied. Moreover, it is shown that the results can be refined in the convex case.     

Sensitivity analysis in multiobjective optimization

Sensitivity analysis in multiobjective optimization is dealt with in this paper. Given a family of parametrized multiobjective optimization problems, the perturbation map is defined as the set-valued map which associates to each parameter value the set of minimal points of the perturbed feasible set in the objective space with respect to a fixed ordering convex cone. The behavior of the perturbation map is analyzed quantitatively by using the concept of contingent derivatives for set-valued maps. Particularly, it is shown that the sensitivity is closely related to the Lagrange multipliers in multiobjective programming.This research was made while the author stayed at the International Institute for Applied Systems Analysis, Laxenburg, Austria.The author would like to thank an anonymous referee for his helpful suggestions; particularly, he pointed out that Proposition 2.2 and Theorem 2.1 are valid also in infinite-dimensional spaces.     

Synthesis of L-epi-capreomycidine derivatives via C-H amination

The L-epi-capreomycidine (Cpm) derivatives were efficiently and stereoselectively synthesized via nitrene C-H insertion starting from a readily available D-Tyr. Design of a substrate that takes into account hydrogen bonding is a critical feature in order to achieve high selectivity. Our synthetic strategy could be a new access to epi-Cpm and its derivatives, which are found in several biologically active natural products.     

Direct synthesis of fluorescent 1,3a,6a-triazapentalene derivatives via click-cyclization-aromatization cascade reaction

An efficient and versatile method was established for the preparation of 1,3a,6a-triazapentalenes. The 1,3a,6a-triazapentalene skeleton without an additional fused ring system was discovered to be a compact and highly fluorescent chromophore, which exhibited various interesting fluorescent properties such as a noteworthy correlation of luminescent wavelength with the Hammett σ(p) value and a strongly positive solvatofluorochromism.