Abstract-Formal synthesis of the telomerase inhibitory marine pyrrolocarbazole alkaloid dictyodendrin B is described. The key features are consecutive palladium-catalyzed cross-coupling reactions and intramolecular reductive coupling reaction to construct the pyrrolo[2,3-c]carbazole framework.

The development of the first intermolecular Rh2(II)-catalyzed aziridination of olefins using anilines as nonactivated N atom precursors and an iodine­(III) reagent as the stoichiometric oxidant is reported. This reaction requires the transfer of an N-aryl nitrene fragment from the iminoiodinane intermediate to a Rh2(II) carboxylate catalyst; in the absence of a catalyst only diaryldiazene formation was observed. This N-aryl aziridination is general and can be successfully realized by using as little as 1 equiv of the olefin. Di-, tri-, and tetrasubstituted cyclic or acylic olefins can be employed as substrates, and a range of aniline and heteroarylamine N atom precursors are tolerated. The Rh2(II)-catalyzed N atom transfer to the olefin is stereospecific as well as chemo- and diastereoselective to produce the N-aryl aziridine as the only amination product. Because the chemistry of nonactivated N-aryl aziridines is underexplored, the reactivity of N-aryl aziridines was explored toward a range of nucleophiles to stereoselectively access privileged 1,2-stereodiads unavailable from epoxides, and removal of the N-2,4-dinitrophenyl group was demonstrated to show that functionalized primary amines can be constructed.

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Please cite this article as: Tanifuji, R., Oguri, H., Koketsu, K., Yoshinaga, Y., Minami, A., Oikawa, H., Catalytic asymmetric synthesis of the common amino acid component in the biosynthesis of tetrahydroisoquinoline alkaloids, Tetrahedron Letters (2015), doi: http://dx.

Previously we developed a promising synthetic approach to complex polycyclic natural products, including aromatic polyketides derived from the type-II polyketide biosynthesis. The approach consists of three key steps; (1) cycloaddition or cyclocondensation of nitrile oxide for assembling the carbon skeleton having an isoxazole as a 1,3-diketone equivalent, (2) benzoin cyclization for stereoselective ring fusion with an angular hydroxy group, and (3) oxidation of isoxazolium salt for installing an additional angular hydroxy group in stereoselective manner. As a synthetic exercise to highlight the utility of this approach, the first total syntheses of the proposed structure of pleospdione (1) and its C3-epimer (3-epi-1) have been achieved. The synthesis has proved the efficiency of the strategy as an entry into polyketide-derived complex architectures.At the same time, it was revealed that neither 1 nor 3-epi-1 represent the true structure of the natural product by incongruity of the NMR spectra.

We synthesized the novel methacrylate monomer bearing an oxazolidone structure (M1) and performed radical polymerization of M1 by traditional procedures. The glass transition temperature (Tg) of the obtained polymer (P1) was a significantly high value compared to that of poly(methyl methacrylate) and typical poly(urethane methacrylate)s. The copolymers of M1 and monofunctional urethane methacrylate derived from 2‐hydroxyethyl methacrylate and phenyl isocyanate (M2) exhibited a linear rise of the Tg values depending on the composition ratio of M1. The NMR analysis and the estimation of monomer reactivity ratio and Q–e values suggested that the improvement of glass transition temperature resulted from a stereoregularity, meaning a syndiotacticity of the copolymers improved with increasing the composition ratio of M1. Furthermore, the thermal curing reaction of M1 or M2 with bifunctional urethane acrylate successfully proceeded, then the Tg value of the cured product from M1 was much higher than that from M2.

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The development of the first intermolecular Rh₂(II)-catalyzed aziridination of di-, tri-, or tetraubstituted olefins using aryl- or heteroaryl amines as nonactivated N-atom precursors and an iodine(III) reagent as the stoichiometric oxidant is reported. The Rh₂(II)-catalyzed N-atom transfer to the olefin is stereospecific, chemo- and diastereoselective to produce the <i>N</i>-aryl aziridine as the only amination product.