HETEROCYCLES
An International Journal for Reviews and Communications in Heterocyclic ChemistryWeb Edition ISSN: 1881-0942
Published online by The Japan Institute of Heterocyclic Chemistry
Special Issue
Yasuyuki Kita's Special Issues, Vol. 103, No. 2, 2021
Published online: 23rd March, 2021
■ Claisen Rearrangement of 4-Allyloxy-1-p-methoxy benzylpyrazole and Synthesis of Pyrazole-Fused 7-Membered Lactones
Hayato Ichikawa,* Hiroki Takashima, and Shoichi Shimizu
*College of Industrial Technology, Nihon University, 1-2-1, Izumi-cho, Narashino, Chiba 275-8575, Japan
Abstract
Allyl 4-pyrazolyl ethers were subjected to the Claisen rearrangement that involved heating under microwave condition to prepare the corresponding products with regioselective allylation at 5-position of the pyrazoles in good yields. The rearrangement products were converted into 7-membered pyrazololactones having an oxygen atom at 4-position of pyrazole, via a hydroesterification reaction with Pd(OAc)2 and DPE-phos as ligand under 40 atm of CO/H2 (6:34) in moderate to excellent yields.
Published online: 26th March, 2021
■ Decisive Effects of C-N Axial Chirality of Intermediary Enolates on the Stereochemical Course of β-Lactam Formation from β-Branched α-Amino Acid Derivatives via Memory of Chirality
Ryuichi Hyakutake, Tomoyuki Yoshimura, Takahiro Sasamori, Norihiro Tokitoh, Kazuhiro Morisaki, and Takeo Kawabata*
*Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto, 611-0011, Japan
Abstract
Stereochemistry of β-lactam formation of β-branched β-amino acid derivatives via a MOC strategy was investigated. The 4-exo-trig cyclization of axially chiral enolates generated from l-threonine and l-allo-threonine derivatives proceeded predominately with inversion of the configuration at the newly formed tetrasubstituted carbon, irrespective of the chirality at the β-carbon of the β-lactam precursors. These results indicated that C–N axial chirality of the intermediary enolates generated from the α-amino acid derivatives has decisive effects on the stereochemical course of β-lactam formation even in the presence of an sp3-chiral center at the β-carbon.
Published online: 18th December, 2020
■ Catalytic Asymmetric Ring-Opening of σ-Symmetric Cyclic Carbonates with Chiral Amino Sulfonamide Catalysts
Michiyasu Nakao, Tomomi Shozui, Daisuke Inoue, Takahito Ihara, Syuji Kitaike, and Shigeki Sano*
*Graduate School of Pharmaceutical Sciences, Tokushima University, 1-78 Sho-machi, Tokushima 770-8505, Japan
Abstract
Enantioselective ring-opening of σ-symmetric six-membered cyclic carbonates with benzyl alcohol catalyzed by 20 mol% of chiral amino sulfonamide catalysts afforded chiral acyclic carbonates in up to 79% ee.
Published online: 10th December, 2020
■ An Arylative Aziridination Process toward Aspidosperma Alkaloids
Kouassi Signo, Elsa Deruer, Siomenan Coulibali, and Sylvain Canesi*
*Laboratoire de Méthodologie et Synthèse de Produits Naturels, Université du Québec à Montréal, C.P. 8888, Succ. Centre-Ville, Montréal, H3C 3P8, Québec, Canada.
Abstract
An arylative aziridination process has been developed from dibrominated phenols containing a Fukuyama sulfonamide on the lateral chain. A two-step procedure involving the formation of a dienone by a phenol oxidation reaction mediated by a hypervalent iodine reagent (Kita reaction) followed by an intramolecular arylative aziridination process was used. This second step occurred under mild conditions via a Michael–Smiles ring-closure cascade, producing sulfur dioxide as the only byproduct. Additionally, a stereoselective approach was observed with tyrosine derivatives. This transformation respects the rules of green chemistry and atom economy. These new polyfunctionalized scaffolds could offer several synthetic possibilities for the total synthesis of natural products such as the main core of Aspidosperma alkaloids.
Published online: 8th February, 2021
■ Deprotection of the Carbazole PMB Group Using Hypervalent Iodine Reagent Combined with N-Hydroxyphthalimide
Kana Yoshikawa, Takanori Tabata, Kazuma Fujimura, Natsumi Kuraoka, Akira Nakamura, Yasuyoshi Miki, and Tomohiro Maegawa*
*School of Pharmaceutical Sciences, Kindai University, 3-4-1 Kowakae, Higashi-osaka, Osaka, 577-8502, Japan
Abstract
We developed a novel method for deprotecting the N-PMB group of carbazoles. The combination of PhI(OAc)2 and N-hydroxyphthalimide cleaved the N-PMB group with moderate to good yields depending on the substituents on the carbazole ring.
Published online: 28th January, 2021
■ Total Synthesis of Urolithin C 3-Glucuronide
Katsunori Itaya, Ishtiaq Jeelani, and Hitoshi Abe*
*Department of Applied Chemistry, Faculty of Engineering, Toyama University, Gofuku 3190, Toyama 930-8555, Japan
Abstract
Urolithin is a metabolite of a class of compounds known as polyphenolswhich are found in various fruits, including pomegranates, nuts and strawberries. Urolithin is a biologically-active compound which has anti-inflammatory, antioxidant and anticancer properties. Our laboratory has focused on the use of a palladium-catalyzed intramolecular biaryl coupling reaction to yield urolithin C 3-glucuronide (uro-C 3-glur). The total synthesis of uro-C 3-glur has been accomplished in 11 steps starting from the commercially-available 3,4-dimethoxybenzaldehyde. We now report full details of the total synthesis of urolithin C 3-glucuronide (1).
Published online: 10th February, 2021
■ Chiral Phosphine Oxide-Catalyzed Enantioselective Ring Opening of Oxetanes
Shunsuke Kotani,* Yuka Tashima, Hiroki Tanaka, Shohei Aoki, and Makoto Nakajima*
*Graduate School of Pharmaceutical Sciences, Kumamoto University, 5-1 Oe-honmachi, Chuo-ku, Kumamoto, Japan
Abstract
Chiral phosphine oxide as a Lewis base could effectively catalyze the enantioselective ring opening of 3-substituted oxetanes with silicon tetrachloride in the presence of N,N-diisopropylethylamine, affording the corresponding 2-substituted 1,3-chlorohydrins in high yields and good enantioselectivities.
Published online: 5th March, 2021
■ On the Order of Addition of Sodium Dispersion in Reductive Diborations of Stilbene and 1,2-Diphenylcyclopropane
Shuo Wang, Atsushi Kaga, and Hideki Yorimitsu*
*Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo, Kyoto 606-8502, Japan
Abstract
Two extreme methods to add sodium dispersion were investigated in the 1,2-diboration of stilbene and the ring-opening 1,3-diboration of 1,2-diphenylcyclopropane on a 20-mmol scale. Method 1 denotes that a substrate is added to a mixture of sodium dispersion and a boron electrophile. Method 2 denotes that sodium dispersion is slowly added to a mixture of a substrate and a boron electrophile. In these four cases, no significant differences were observed in the yields of the products and their syn/anti ratios, except for the diboration of stilbene by Method 1, wherein aggregation of sodium dispersion in the flask and 5% recovery of stilbene were observed. This information would be helpful in performing sodium-dispersion-mediated transformations on a large scale.
Published online: 15th February, 2021
■ Total Synthesis of (±)-4-Deoxyblennolide C via Spirochromanone
Takuya Kumamoto,* Sho Hasegawa, Kanna Adachi, and Kazuaki Katakawa
*Department of Synthetic Organic Chemistry, Graduate School of Biomedical and Health Sciences, Hiroshima University, 1-2-3 Kasumi Minami-ku, Hiroshima, 734-8553, Japan
Abstract
We report the total synthesis of (±)-4-deoxyblennolide C, a deoxy analogue of xanthone antibiotics blennolide C isolated from the fermentation broth of Blennoria sp. The synthesis involves construction of a quaternary carbon during the formation of spirochromanone through the aldol reaction of o-hydroxyacetophenones and cyclohexenone, oxidative cleavage of the alkene moiety, and the construction of a xanthone framework by Dieckmann condensation.
Published online: 17th February, 2021
■ Diastereo- and Enantioselective Intramolecular 1,6-C–H Insertion Reaction of Diaryldiazomethanes Catalyzed by Chiral Dirhodium(II) Carboxylates
Motoki Ito, Yuji Kondo, Ryosuke Namie, Yoshihiro Natori, Koji Takeda, Hisanori Nambu, Masahiro Anada,* Yasunori Yamamoto, and Shunichi Hashimoto*
*Faculty of Pharmacy, Musasino University, Shinmachi 1-1-20, Nishitokyo, Tokyo, Japan
Abstract
A highly diastereo- and enantioselective intramolecular 1,6-C–H insertion reaction of diaryldiazomethanes possessing an ether group has been achieved with the use of dirhodium(II) tetrakis[N-phthaloyl-(S)-tert-leucinate] as a catalyst, providing exclusively 3-substituted cis-3,4-dihydro-4-phenyl-1H-isochromans in up to 99% ee with no evidence of tandem ylide formation–rearrangement.
Published online: 25th January, 2021
■ Synthesis of 1-Azaazulenes Using Ring-Opening Cyclization of Spirocyclopropane with Amine
Hisanori Nambu,* Yuta Onuki, Koga Yamazaki, and Takayuki Yakura
*Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, 2630 Sugitani, Toyama 930-0194, Japan
Abstract
Synthesis of 1-azaazulenes using ring-opening cyclization of spirocyclopropane with a primary amine was accomplished. The reaction of cycloheptane-1,3-dione-2-spirocyclopropane with 2,4-dimethoxybenzylamine in refluxing acetonitrile resulted in a 94% yield of 1,2,3,6,7,8- hexahydrocyclohepta[b]pyrrol-4(5H)-one. The obtained product was successfully converted into 1-azaazulenes by deprotecting the amino-protecting group followed by oxidation.
Published online: 15th March, 2021
■ Large-Scale Synthesis of Thio-glucose-Conjugated Chlorin e6 for Photodynamic Therapy
Akihiro Nomoto,* Hiroaki Yamaguchi, Masato Masuda, Keisuke Hyakumura, Shintaro Kodama, Tomohiro Osaki, Yoshiharu Okamoto, Mamoru Tanaka, Hiromi Kataoka, Atsushi Narumi, Tomokazu Yoshimura, Shigenobu Yano, and Akiya Ogawa
*Engineering, Department of Applied chemistry, Osaka Prefecture University, Sakai, Osaka 593-8531, Japan
Abstract
Chlorin e6 is a heterocycle exhibiting spectral absorption in the 600–700 nm wavelength range used for photodynamic therapy (PDT). Herein, a sugar-conjugated chlorin e6 derivative was synthesized on a large scale. An alkyl spacer was fabricated by controlling the alkylation conditions between the thio-sugar and chlorin e6 and thio-glucose-conjugated chlorin e6 was successfully synthesized.