The total synthesis and development of a variety of bioactive compounds have been accomplished by using unique synthetic strategies and methodologies. Coriolin, rosmarinecine and a side-chain of cephem antibiotics are synthesized through new skeletal rearrangements. Several compounds having naphthopyran and naphthofuran are synthesized by tandem Michael-Dieckmann type reactions. A general method of entry into densely functionalized carbacycles is featured to synthesize a few enzyme inhibitors. The first total synthesis of an anti-HIV, terpestacin, is described and, finally the one-step total synthesis of pyroglutamyl peptidase inhibitor is also discussed.
The chemical, site-specific oxidations of saturated hydrocarbons as mimic for biological process are important subjects in synthetic organic chemistry. Such oxidations are seldom achieved in conventional chemistry. The development of such methodology is challenging, extensive studies which are currently ongoing in many laboratories. Recently we found that the electrochemical oxidation can achieve the site-specific hydroxylation of a certain inactivated methine and methylene groups in moderate or good yields. Further we achieved stereoselective chlorination of steroidal double bonds and selective cleavage of styrylic olefins as well as the triene of vitamin D2 by electrolysis. Descried herein are the scope and limitation, and the synthetic application of such electrochemical oxidation reactions.
Novel methods for the reduction of α, β-epoxy ketones, α, β-epoxy esters (glycidic esters), and their congeners to β-hydroxy carbonyl compounds (aldols) by the use of organoselenium reagents are described. The reagents, a sodium phenylseleno (triethyl) borate complex Na [PhSeB (OEt) 3] easily prepared by reduction of (PhSe) 2 with NaBH4 in EtOH and benzeneselenol (PhSeH) generated in situ from the borate complex by addition of acetic acid, have been demonstrated to serve as excellent reducing agents for these transformations. The organoselenium-mediated reduction of α, β-epoxy carbonyl compounds regiospecifically occurs at the α-carbon to produce a wide variety of cyclic (intramolecular) aldols as well as acyclic (intermolecular) ones in excellent yields. Quantitative mechanistic studies have revealed that the organoselenium-mediated reduction proceeds via an α-substitution process in contrast to the common electron transfer reducing agents. Application of the methods to natural product synthesis such as santanolides (dehydroisoerivanin, isoerivanin, ludovicin C, and 1α, 3α-dihydroxyarbusculin B), diarylheptanolides (yashabushiketol, yashabushiketodiol A and yashabushiketodiol B), plant toxins picrotoxinin and picrotin, and a corn host-specific pathotoxin PM-toxin A is described.
Electron transfer (ET) reaction in biological systems plays an important role in respiratory oxidative phosphorylation and photosynthesis. In the respiratory system, two electron carriers, ubiquinone and cytochrome c, control the overall reaction of ET process via specific interaction with membrane-bound oxidoreductases. The present review describes two topics of the synthetic modeling of noncovalently linked donor-acceptor systems using porphyrin unit; (1) preparation and characterization of ubiquinone receptors by use of a functional porphyrin, which shows the photoinduced ET reaction within the porphyrin-quinone complex formed by hydrogen bonding interaction. (2) construction of binding sites on the surface of myoglobin and mimicking of protein-protein complexation. In this review, I wish to report the suitable model systems to evaluate the intermolecular ET of the electron carriers via molecular recognition.
Since the discoveries of an organic metal by a TTF-TCNQ complex in 1973 and of an organic superconductor by a PF6 salt of TMTSF radical cation in 1979, respectively, TTF and its derivatives continue to play a crucial role in the development of new organic conductors, especially organic superconductors with higher Tc. In addition, TTF and its derivatives are expected as key molecules for the development of single component organic metals, the material systems in coexistence of conducting π electrons and localized d or π spins, high spin systems, and infrared absorption materials. The present review mainly present our results on new TTF derivatives synthesized with aim at other novel magnetic, optical, magnetic/electrical properties than electrical conductivity.
4-Alkoxy-5-amido-2-carbamoyl-1-naphthols were developed as novel cyan dye-forming couplers for color-negative film. The couplers react with oxidized product of color developing agent efficiently, and afford cyan dyes stable to heat and light. Copper catalyzed alkoxylation reaction of 5-amido-4-bromo-2-carbamoyl-1-naphthol was a key step in the synthesis of the couplers, and proceeded efficiently at room temperature. In general, copper catalyzed aromatic nucleophilic substitution reactions require high temperature and assist by electron-withdrawing groups (ex. nitro group), therefore, the present results were very attractive. Because 8-bromo-1-amidonaphthalenes (substrate lacked of hydroxyl group) reacted as well as the couplers, while 4-bromo-2-carbamoyl-1-naphthols (substrate lacked of amide group) did not react under the same conditions, the neighboring amide group was essential, and probably participated in the reaction. The participation by an amide group in copper catalyzed aromatic nucleophilic substitution reaction was known scarcely, the reaction was expected as a new synthetic route for some useful compounds. This paper also describes a few examples of synthetic application to some useful phenol derivatives.
To date, the resolution of racemic mixture via diastereomeric salt formation has been the most commonly used industrial technique. We have synthesized and applied new resolving agents for industrial application. Practical approach to the developments is as follows. Optically active 2-phenoxypropionic acid and tartranilic acid are readily employed for the resolution of bases, and 1-benzylamino-3-phenoxy-2-propanol for the resolution of acids.