In the present review, we will summarize recent studies on photochemistry of supramolecules using imides. Recently, imides have been employed in various functional molecular systems including biomolecules, solar cells, and molecular devices, because of its excellent photophysical and electron accepting properties. Our research groups also employed imides in various supramolecular systems including DNA and so on. First we describe fundamental properties of imides such as photophysical and electrochemical properties. Then, photophysical properties of imides in supramolecular systems will be introduced. Furthermore, photoinduced processes of imides combined with electron donor will be described. Examples of imides used in the research of the higher excited state chemistry will be also introduced. The higher excited state chemistry has been investigated by single and multi-laser techniques. Then, future perspective in this field will be introduced.
Organic fluorescent hosts which can exhibit sensitive color and fluorescence changes upon formation of host-guest inclusion complexes in the crystalline state can be one of the most promising materials for the construction of desirable solid-state fluorescent system and are attractive materials for their potential applications in analytical and material sciences. For this purpose, we have designed and synthesized several kind of heterocyclic quinol-type fluorescent hosts, (benzofurano[1,2-d]naphthoquionl-type, benzo[kl]xanthenol-type, benzofurano[3,2-b]naphthoquinol-type, and imidazo[5,4-a]anthraquinol-type fluorophores) whose crystals exhibit a dramatic fluorescence enhancement upon inclusion of various kinds of organic solvent molecules. The magnitude of the solid-state fluorescence enhancement is greatly dependent on the enclathrated guest molecules. It is confirmed from the spectral data and the X-ray crystal structures that the destruction of the host-host π-π interactions by the enclathrated guest molecules is the main reason for the guest-dependent fluorescence enhancement behavior. Furthermore, we found that these heterocyclic quinol-type fluorescent clathrands exhibit color and fluorescence changes upon exposure to various solvent vapors both in the crystalline state and thin-film state. We believe that these results are useful for the development of new solid-emissive chemosensors and for the improvement of pigmentary solid-state fluorescence in the applied field of optoelectronic devices.
A highly effective reaction is described, which involves the pseudo intramolecular process. The acyl groups of β-keto esters are activated by α-arylation or α-nitration, and are easily transferred to amines without forming any by-product. This reaction is initiated by forming ammonium enolate. When the amine is liberated under equilibrium, the nucleophilic amine and the electrophilic keto ester are close together, which undergoes the effective substitution like the intramolecular reaction despite the intermolecular reaction; it is called pseudo intramolecular process. This concept is applicable to other substrates having both acidic hydrogen and functionality to furnish polyfunctionalized compounds those are not easily prepared by alternative procedure.
This review describes the recent application of trimethylsilyldiazomethane (Me3SiCHN2, TMSCHN2), its lithium and magnesium bromide salts [TMSC(Li)N2 and TMSC(MgBr)N2] to the synthesis of heterocycles. Reaction of TMSCHN2 with acyl isocyanates followed by Diels-Alder reaction with propiolates or N-phenylmaleimide affords furans or bicyclic pyridones in a one-pot process, respectively. In addition, TMSCHN2 is useful for the preparation of 2-azaazulenes, aziridines and indolizines. Meanwhile, TMSC(Li)N2 reacts with benzynes generated from halobenzenes to yield 3-trimethylsilylindazoles, which are easily converted to 1-arylindazoles or indazoles bearing 3-hydroxymethyl units. TMSC(Li)N2 is also applicable to the synthesis of indoles, benzofurans, pyrroles, thiophenes and 2,3-benzodiazepines. By using TMSC(MgBr)N2, α-substituted β-trimethylsilyl-α,β-epoxyesters can be synthesized from α-ketoesters in a one-pot process. Reaction of TMSC(MgBr)N2 with carbonyl compounds efficiently furnishes trimethylsilylated diazoalcohols, which react with propiolates to give di- or tri-substituted pyrazoles.
The first total syntheses of new monoterpene alkaloids (-)-incarvilline, (+)-incarvine C, and (-)-incarvillateine, corresponding to the natural enantiomers, have been accomplished. The strategy for the synthesis of these natural products utilized 6-epi-incarvilline as a common precursor, which was assembled by a three-component coupling reaction using (4S)-4-siloxy-2-cyclopenten-1-one to construct an appropriately trisubstituted cyclopentanone, followed by ring closure to the cis-perhydro-2-pyrindine skeleton by means of a reductive Heck-type reaction. An alternative ring closure to the cis-perhydro-2-pyrindine skeleton was also carried out employing intramolecular enone-olefin [2+2] photocycloaddition. Furthermore, topochemically controlled [2+2] photodimerization of ferulic acid derivatives in the solid state for the stereospecific construction of a 1,2,3,4-tetrasubstituted cyclobutane ring was investigated as a means to access (-)-incarvillateine.
One-carbon homologation or elongation of carbonyl compounds utilizing the rearrangement of carbenes or carbenoids as the key reaction is described. In the first chapter, one-carbon elongation of ketones and aldehydes, including one-carbon ring-expansion of cyclic ketones, by using dibromomethyllithium or lithium α-sulfinyl carbanion of 1-chloroalkyl p-tolyl sulfoxides as one-carbon homologating agents is discussed. The synthetic method for α-halo, α-sulfanyl, and α-sulfinyl carbonyl compounds from ketones and aldehydes with one-carbon elongation is summarized in the second chapter. In the third chapter, one-carbon elongation of carboxylic acids, esters, and acid chlorides to carboxylic acids and their derivatives by using dibromomethyllithium and lithium α-sulfinyl carbanion of chloromethyl p-tolyl sulfoxide as one-carbon homologating agents is discussed.
Preparation of functionalized organometallic reagents is widely used in organic synthesis. Convenient, practical, and economical methods for preparation of functionalized organometallics were highly demanded. Recently, Knochel et al. reported direct metal insertion into carbon-halogen bond was dramatically promoted in the presence of lithium chloride. This method was applicable to prepare organozinc, -magnesium, and -indium reagents.