Wiley Acta Medica Okayama 1433-7851 2025 Development of a Vinylated Cyclic Allene: A Fleeting Strained Diene for the Diels–Alder Reaction e202510319 EN Haruki Mizoguchi Graduate School of Environmental, Life, Natural Science and Technology, Okayama University Takumi Obata Graduate School of Environmental, Life, Natural Science and Technology, Okayama University Taiki Hirai Graduate School of Environmental, Life, Natural Science and Technology, Okayama University Manaka Komatsu Graduate School of Environmental, Life, Natural Science and Technology, Okayama University Akira Sakakura Graduate School of Environmental, Life, Natural Science and Technology, Okayama University Fleeting molecules possessing strained multiple bonds are important components in organic synthesis due to their ability to undergo various chemical reactions driven by the release of strain energy. Although the use of strained π-bonds as 2π components, represented by dienophiles in Diels–Alder reactions, has been well studied, “the strained diene (4π component) approach” for molecular construction remains underexplored. Herein, we report the design of a vinyl cyclic allene (1-vinyl-1,2-cyclohexadiene) as a highly reactive strained diene and the development of its Diels–Alder reactions. Experimental and computational studies of vinyl cyclic allenes revealed that this diene system undergoes cycloaddition with dienophiles regio- and stereoselectively under mild reaction conditions. These studies also provide insight into the reactivity and selectivity of the system. The strained diene approach enables the convergent construction of polycyclic molecules through bond disconnections distinct from conventional retrosynthetic analysis, thus offering an efficient strategy for the assembly of functional molecules. No potential conflict of interest relevant to this article was reported.

ROYAL SOC CHEMISTRY Acta Medica Okayama 2041-6520 13 2022 Annulative coupling of vinylboronic esters: aryne-triggered 1,2-metallate rearrangement 9580 9585 EN Haruki Mizoguchi Graduate School of Natural Science and Technology, Okayama University Hidetoshi Kamada Graduate School of Natural Science and Technology, Okayama University Kazuki Morimoto Graduate School of Natural Science and Technology, Okayama University Ryuji Yoshida Graduate School of Natural Science and Technology, Okayama University Akira Sakakura Graduate School of Natural Science and Technology, Okayama University A stereoselective annulative coupling of a vinylboronic ester ate-complex with arynes producing cyclic borinic esters has been developed. An annulation reaction that proceeded through the formation of two C-C bonds and a C-B bond was realized by exploiting a 1,2-metallate rearrangement of boronate triggered by the addition of a vinyl group to the strained triple bond of an aryne. The generated aryl anion would then cyclize to a boron atom to complete the annulation cascade. The annulated borinic ester could be converted to boronic acids and their derivatives by oxidation, halogenation, and cross-coupling. Particularly, halogenation and Suzuki-Miyaura coupling proceeded in a site-selective fashion and produced highly substituted alkylboronic acid derivatives. No potential conflict of interest relevant to this article was reported.

American Chemical Society (ACS) Acta Medica Okayama 0022-3263 86 14 2021 Toward the Synthesis of Paspaline-Type Indole-Terpenes: Stereoselective Construction of Core Scaffold with Contiguous Asymmetric Quaternary Carbon Centers 9802 9810 EN Ichiro Hayakawa Graduate School of Integrated Basic Sciences, Nihon University, 3-25-40 Sakurajosui, Setagaya-ku, Tokyo 156-8550, Japan Naochika Matsumaru Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan Akira Sakakura Graduate School of Natural Science and Technology, Okayama University, 3-1-1 Tsushima-naka, Kita-ku, Okayama 700-8530, Japan The core scaffold of paspaline-type indole-terpenes was synthesized by using the House–Meinwald rearrangement as a key step. Rearrangement of the epoxide methyl group in the precursor with MABR (methylaluminum bis(4-bromo-2,6-di-tert-butylphenoxide)) as a Lewis acid proceeded smoothly to construct contiguous asymmetric quaternary carbon centers by a 1,2-chirality transfer. No potential conflict of interest relevant to this article was reported.

American Chemical Society Acta Medica Okayama 0022-3263 85 2 2019 Formal Total Synthesis of Manzacidin B via Sequential Diastereodivergent Henry Reaction 798 805 EN Yuya Araki Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University Natsumi Miyoshi Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University Kazuki Morimoto Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University Takayuki Kudoh Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University Haruki Mizoguchi Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University Akira Sakakura Division of Applied Chemistry, Graduate School of Natural Science and Technology, Okayama University A formal total synthesis of manzacidin B is described. beta,beta-Disubstituted gamma-hydroxy-beta-aminoalcohol, the key structure of manzacidin B, is stereoselectively constructed via sequential Henry reactions. By taking advantage of noncovalent interactions, such as intramolecular hydrogen bonding and chelation, we could diastereodivergently control the stereoselectivity of the Henry reaction. No potential conflict of interest relevant to this article was reported.

American Chemical Society Acta Medica Okayama 1523-7060 21 7 2019 Thioureas as Highly Active Catalysts for Biomimetic Bromocyclization of Geranyl Derivatives 2073 2076 EN Miyuki Terazaki Graduate School of Natural Science and Technology, Okayama University Kei-ichi Shiomoto Graduate School of Natural Science and Technology, Okayama University Haruki Mizoguchi Graduate School of Natural Science and Technology, Okayama University Akira Sakakura Graduate School of Natural Science and Technology, Okayama University Thioureas bearing electron-deficient aryl groups show high catalytic activity in the biomimetic bromocyclization of geranyl derivatives. The reaction of geranyl derivatives with N-bromosuccinimide (NBS) proceeds rapidly in CH2Cl2 to give the corresponding bromocyclization products in high yields as a ca. 1:1 mixture of endo- and exo-isomers. The reactivity of geranyl derivatives highly depends on the terminal substituent: electron-donating substituents increase the reactivity, while electron-withdrawing substituents decrease the reactivity. No potential conflict of interest relevant to this article was reported.

Royal Society of Chemistry Acta Medica Okayama 1359-7345 55 27 2019 Catalytic enantioselective Hosomi-Sakurai reaction of α-ketoesters promoted by chiral copper(ii) complexes 3923 3926 EN Yutaro Niwa Graduate School of Natural Science and Technology, Okayama University Mayu Miyake Graduate School of Natural Science and Technology, Okayama University Ichiro Hayakawa Graduate School of Natural Science and Technology, Okayama University Akira Sakakura Graduate School of Natural Science and Technology, Okayama University A catalytic enantioselective Hosomi–Sakurai reaction of α-ketoesters has been developed. A copper(II) complex with a chiral bis(oxazoline) ligand bearing methanesulfonamide groups shows excellent catalytic activity to give α,α-disubstituted α-hydroxyesters in high yields with high enantioselectivities. This is the first successful method for the catalytic enantioselective 1,2-addition of α-ketoesters with allylic silanes. No potential conflict of interest relevant to this article was reported.

Georg Thieme Verlag Acta Medica Okayama 0936-5214 30 15 2019 Dipeptide-Derived Chiral Tri- or Diammonium Salt-Catalyzed Enantioselective 1,3-Dipolar Cycloaddition Reaction of Nitrones with a- (Acyloxy)acroleins 1835 1839 EN Chihiro Kidou Graduate School of Natural Science and Technology, Okayama University Haruki Mizoguchi  Graduate School of Natural Science and Technology, Okayama University Tatsuo Nehira Graduate School of Integrated Sciences for Life, Hiroshima University Akira Sakakura Graduate School of Natural Science and Technology, Okayama University Organoammonium salts of dipeptide-derived chiral tri-amines or diamines with TfOH catalyzed the enantioselective 1,3-dipolar cycloaddition reactions of alpha-acyloxyacroleins with nitrones to give the corresponding adducts in good yields (up to 96%) and with high diastereo- and enantioselectivities (up to 89% ee). Although alpha-(p-methoxybenzoyloxy)acrolein is rather unstable under the reaction conditions, alpha-(3-pyrroline-1-carbonyloxy)acrolein is stable enough to be smoothly converted into the corresponding adducts with the aid of the chiral organoammonium salt catalysts. No potential conflict of interest relevant to this article was reported.