Synthesis of jaspine B regioisomers through palladium-catalyzed stereoselective tetrahydrofuran formation: Insight into the ligand recognition of sphingosine kinases

We recently reported a structure-activity relationship study of 4-epi-jaspine B derivatives toward sphingosine kinase (SphK) and identified selective inhibitors of two SphK isoforms. In this study, we designed and synthesized jaspine B regioisomers on the basis of palladium-catalyzed tetrahydrofuran formation and late-stage cross metathesis reactions to investigate the influence of the substitution position of functional groups on SphK inhibition. Evaluation of the jaspine B regioisomers SphK inhibitory activities revealed that several of these compounds exhibited comparable SphK1/2 inhibitory potency to that of 4-epi-jaspine B.     

Investigation of the reaction of N-substituted indolylborates: Palladium catalyzed cross-coupling reactions and intramolecular alkyl migration reactions

The palladium catalyzed cross-coupling reaction of indolylborates with various N-protecting groups was investigated, where N-Methyl, N-methoxy, and N-tert-butoxycarbonyl groups were found to be useful. However, triethyl(1-methoxymethylindol-2-yl)borate could not be used for this reaction. It was also found that the alkyl migration reaction of trialkyl(1-methoxymethylindol-2-yl)borate produced 2-alkyl-1-methyl-indole accompanied by the unexpected reduction of 1-methoxymethyl group to 1-methyl group.     

Monitoring of Dynamic Behavior of Phospholipids at Liquid/Liquid Interfaces by a Time-Resolved Quasi-Elastic Laser-Scattering Method

Phospholipids, which consist of a zwitterionic head group connected to a pair of long hydrocarbon chain, constitute the major component of most cell membranes. A monolayer composed of phospholipids at the interface between two immiscible liquids is a useful model system for studying biological and artificial membranes.     

Behavior of Tetraalkylammonium Bromide in Phase Transfer Catalytic Reaction at a Liquid/Liquid Interface as Studied by a Quasi-Elastic Laser Scattering Method

The liquid/liquid interface plays important roles in various processes such as phase transfer catalyst,solvent extraction and ion-selective electrode.     

Steric‐Factor‐Directed Alternating Supramolecular Copolymer Composed of Hydrogen‐Bonded Cyclohexanetricarboxamide Units

Hydrogen‐bonded supramolecular copolymers were easily prepared by mixing cyclohexanetricarboxamides with three ( 1 ) and six ( 2 ) alkylsilyl groups, and supramolecular fibers were fabricated. When the composition of 1 and 2 was at or close to equimolarity, the supramolecular copolymer chain was found to have an alternating sequence. This was attributed to the fact that the steric factor of the alkylsilyl side chains effectively controls the unit sequence of the supramolecular polymer chain.

     

Synthesis of end-capped polyester from SmI2-catalyzed Tishchenko-type polyaddition of dialdehydes

SmI₂-catalyzed polyaddition of 1,12-dodecanedial followed by treatment with benzaldehyde gives a polyester (1) containing three structural units, [OCH₂-(CH₂)₁₀-CH₂O], [OCH₂-(CH₂)₁₀-CO], and [CO-(CH₂)₁₀-CO], in the main chain and an OCH₂Ph end-capping group. GPC analysis of 1 shows molecular weights of M_n = 5.5 × 10³ and M_w = 14 × 10³. The ¹H-NMR spectrum reveals the polymer structure with the COOCH₂Ph end group as well as the M_n value (2.6 × 10³) calculated based on an amount of the end-capping group and lower than that estimated from GPC. Mixtures of terephthalaldehyde and 1,12-dodecanedial in several molar ratios undergo similar polyaddition catalyzed by SmI₂ to give the corresponding copolyesters after treatment with benzaldehyde. Increase in the ratio of 1,12-dodecanedial causes increase in yield and molecular weight of the copolymer. Terephthalaldehyde shows a tendency to give alcohol-side —O—R—O— unit in the polyester, whereas 1,12-dodecanedial is mostly incorporated as the acid-side —CO—R′—CO— unit. Terminal aldehyde group derived from dodecanedial is capped effectively by benzaldehyde to give the COOCH₂Ph end group. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 2821–2825, 1997