HETEROCYCLES

■ Contents

■ Umpolung of Electron-Rich Heteroarenes with Hypervalent Iodine Reagents

Pamela Pal,(a) Jerome Waser,(b)*and Raj Kumar Nandi(a)*


* a Department of Chemistry, Diamond Harbour Women’s University, Sarisha, West Bengal-743368, India
* b ISIC-SB-LCSO, Ecole Polytechnique Federale de Lausanne (EPFL), Av. Forel 2, BCH 1402, Switzerland

Abstract

Five-membered heterocycles are well known for their innate nucleophilicity. In contrast, reaction of these heterocycles as electrophiles is less established and has become only recently an intensively investigated research area in synthetic chemistry. The use of hypervalent iodine reagents for the umpolung of the nucleophilic reactivity has been especially successful. This review provides a comprehensive overview regarding the generation of electrophilic intermediates from electron-rich heterocycles using hypervalent iodine reagents. The functionalization with different heteroatoms, arenes or heteroarenes nucleophiles is then described.

■ Combined Brønsted-Base-Mediated Direct C-H Carboxylation of Heteroarenes with CO2

Masanori Shigeno,* Keita Sasaki, Kazuya Hanasaka, Itsuki Tohara, Kanako Nozawa-Kumada, and Yoshinori Kondo*

*Graduate School of Pharmaceutical Science, Tohoku University, 6-3 Aobayama, Sendai 980-8578, Japan

Abstract

This review article summarizes that the combined Brønsted-base system comprising LiO-t-Bu, CsF, and 18-crown-6 efficiently proceeds the direct carboxylation of electron-rich heteroarenes, such as benzothiophene and benzofuran, with CO2. Good functional group compatibility is displayed, allowing the use of Me, MeO, halogen, CN, ketone, and amide moieties. 3-Substituted indoles are also used for C-2 carboxylation, while double-carboxylation of 2-alkylheteroarenes is achieved by LiO-t-Bu and CsF.

■ Conformational Control in Stereoselective Chemical Reactions: From Amino Acids to Iminosugars

Ari Koskinen*

*Department of Chemistry and Material Sciences, Aalto University, Finland

Abstract

Two alternative synthetic strategies for the synthesis of vicinal amino alcohols from naturally occurring amino acids have been investigated, viz. one going through diastereoselective addition of organometallic species to an amino aldehyde and one going through α’-chiral α,β-enones and their diastereoselective reduction. Based on these investigations we were able to develop a synthetic strategy towards all diastereomers of deoxynojirimycin starting from naturally occurring serine through a divergent route with a late stage intermediate that can be prepared in large quantities and in enantiomerically pure form.

■ Recent Development on the Ring Transformation Reactions: Synthesis of Functionalized Benzenes, N-Heterocycles and Fused Ring Systems

Priyanka B. Kole and Fateh V. Singh*

*Chemistry Division (SAS), VIT Chennai, Vandalur-Kelambakkam Road, Chennai, Tamil Nadu, India

Abstract

Ring transformation reactions using 2H-pyran-2-ones as valuable synthetic precursor with several nucleophiles for designing numerous interesting scaffolds is a growing field in synthetic organic chemistry. 2H-Pyran-2-ones has tendency to act as very good Michael acceptor and hence functions as good electrophile. The scope of 2H-pyran-2-ones has been explored for the synthesis of various molecules owning significant biological importance. Additionally, their synthetic potential has been discovered for the construction of interesting photophysically active molecules. From this point of view, the development of simple and environmental benign ring transformation strategy is a dynamic research field until today. This short review describes an overview of the most recent advances in ring transformation of functionalized 2H-pyran-2-ones into valuable aromatic scaffolds like functionalized benzenes, N-heterocycles and fused ring systems.

■ Dihalogenative Cyclization for the Synthesis of 4-Bromo-1-bromoalkyl-5-aryl/alkyl/alkenyl-pyrazoles

Motohiro Yasui, Maki Hasegawa, Keiji Konishi, Norihiko Takeda, and Masafumi Ueda*

*Kobe Pharmaceutical University, Motoyamakita, Higashinada, Kobe 658-8558, Japan

Abstract

A copper-mediated domino reaction involving cyclization, bromination, and nucleophilic substitution of N,N-disubstituted hydrazones, which are labile under oxidative conditions, to synthesize 4-bromo-1-bromoalkyl-5-aryl/alkyl/alkenyl-pyrazoles, is achieved. This method features the simultaneous construction of pyrazoles and two C-Br bonds, which are synthetically useful.

■ Generation of Monoaryl-λ3-iodanes from Arylboron Compounds through ipso-Substitution

Ayako Nakano, Yukino Okabe, Keitaro Matsuoka, Narumi Komami, Keito Watanabe, Masahiro Kojima, Tatsuhiko Yoshino, and Shigeki Matsunaga*

*Faculty of Pharmaceutical Sciences, Hokkaido University, Kita-ku, Sapporo 060-0812, Japan

Abstract

Monoaryl-λ3-iodanes serve as versatile oxidants and arylating reagents in organic synthesis. In addition to the oxidation of iodoarenes, electrophilic substitution reactions using iodine tricarboxylates have been used for the synthesis of monoaryl-λ3-iodanes. Here, we report that ipso-substitution reactions of aryltrifluoroborates with iodine tris(trifluoroacetate) in DMF or DMA smoothly produced monoaryl-λ3-iodanes, which were readily converted to aryliodonium ylides. We also demonstrated that sequential C–H borylation and the ipso-substitution efficiently introduced the I(III) group under steric control.

■ Planar Chiral [2.2]Paracyclophane-Based Bis(thiourea)-Catalyzed Highly Diastereo- and Enantioselective Michael Addition Reaction of Nitroethane to Nitrostyrenes

Shinji Kitagaki,* Eriko Shimo, Sawa Takeda, Rintaro Fukai, Naohiro Kojima, Shun Yoshioka, Naoko Takenaga, and Keisuke Yoshida

*Laboratory of Medicinal Chemistry, Faculty of Pharmacy, Meijo University, 150 Yagotoyama, Tempaku-ku, Nagoya 468-8503, Japan

Abstract

To demonstrate the utility of [2.2]paracyclophane as a chiral organocatalyst backbone, we evaluated a planar chiral pseudo-ortho- [2.2]paracyclophane-based bis(thiourea) catalyst in the Michael addition reaction of nitroethane to nitrostyrenes. The catalyst produced the desired 1,3-dinitro compounds in high yields and high diastereo- and enantioselectivities.

■ Synthetic Studies on Didymeline Using Spirocyclization of Phenols with Diazo Functionality

Mitsuru Ikeda, Hiroki Nakayama, Ayaka Kanda, Shingo Harada,* and Tetsuhiro Nemoto*

*Pharmaceutical Chemistry, Graduate School of Pharmaceutical Sciences, Chiba University, 1-8-1 Inohana, Chuo, Chiba, Japan

Abstract

Didymeline is an alkaloid with an azaspiro tricyclic skeleton with various functionalities. Despite the fact that its unique architecture is synthetically attractive, its total synthesis has never been achieved before. Herein, we present synthetic studies on the core structure of Didymeline. Accordingly, a spiro ring system was constructed through dearomatization of a phenol derivative with α-diazoamide unit. Based on the resulting 2-azaspiro[4,5]decane variant, a tricyclic molecule was synthesized via base-promoted intramolecular ring closure. For an asymmetric synthesis, an enantioselective dearomatization was also examined under silver catalysis, which led to the formation of an all-carbon substituted quaternary stereogenic center.

■ Facile Preparation of 1-Hydroxy-1,2-Benziodoxol-3(1h)-one 1-Oxide (IBX) and Dess–Martin Reagent Using Sodium Hypochlorite under Carbon Dioxide

Kazunori Miyamoto,* Tomohide Okada, Takashi Toyama, Shinji Imamura, and Masanobu Uchiyama*

*Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan

Abstract

We have developed a safe, convenient, and inexpensive method for preparation of the widely used oxidizing agent 1-hydroxy-1,2-benziodoxol-3(1H)-one 1-oxide (IBX), by treatment of 2-iodobenzoic acid with aqueous sodium hypochlorite under CO2 at room temperature. As the only by-product is NaCl, this reaction can be utilized for one-pot synthesis of 1,1,1-triacetoxy-1,2-benziodoxol-3(1H)-one (Dess-Martin reagent) in excellent yield.

■ Chloroamidation of Alkenes Using Sodium Hypochlorite Pentahydrate and Its Application to Synthesis of Aziridines

Masayuki Kirihara,* Kouta Adachi, Yugo Sakamoto, Kazuki Tujimoto, Sho Yamahara, Ryoji Matsushima, Yukou Namba, Kosuke Sato, Takashi Kamada, Yoshikazu Kimura, and Shinobu Takizawa*

*The Institute of Scientific and Industrial Research, Osaka University, 8-1, Mihogaoka, Ibaraki, Osaka 567-0047, Japan

Abstract

The reaction of alkenes with sodium hypochlorite pentahydrate (NaOCl·5H2O) and phosphoric acid (H3PO4) in nitrile solvents resulted in a chloroamidation reaction, producing -chloroamide derivatives in good yields without the use of a transition metal catalyst (up to 90%). N-Pivalazirizines were readily obtained from the resulting -chloroamide derivatives when they were reacted with lithium hexamethyldisilazide (LiHMDS).

■ IBX Oxidations for the Synthesis of Substituted 2H-Pyrans

David R. Williams,* Seth A. Bawel, Nazanin Haddadpour, and Sarah Maier

*Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, IN 47405-7102, U.S.A.

Abstract

Facile oxidation of highly substituted 3,5-hexadien-1-ols using 3-iodoxybenzoic acid (IBX) in DMSO has resulted in a one-pot preparation of 2,3,4,6-tetrasubstituted 2H-pyrans. Cycloisomerizations of the 1-oxatriene moiety, produced in the oxidation, spontaneously occur via a disrotatory oxa-electrocyclization. The 2H-pyran products of Table 1 features three differentiated carbonyl substituents.

■ Gold-Catalyzed Formal [3+2] Cycloaddition of p-Quinones and 1-Phenylpropenes in Ionic Liquid: Environmentally Friendly and Stereoselective Synthesis of 2,3-Dihydrobenzofuran Neolignans

Nobuyoshi Morita,* Kanae Ikeda, Hitomi Chiaki, Ryuto Araki, Kosaku Tanaka III, Yoshimitsu Hashimoto, and Osamu Tamura*

*Laboratory of Organic Chemistry, Pharmaceutical Sciences, Showa Pharmaceutical University, 3-3165, Higashi-tamagawagakuen, Machida, Tokyo 194-8543, Japan

Abstract

Gold(III)-catalyzed formal [3+2] cycloaddition of p-quinones with 1-phenylpropenes in an ionic liquid, [EMIM][NTf2], enabled environmentally friendly, stereoselective synthesis of 2,3-dihydrobenzofuran neolignans in good yields. Moreover, the recycle of tThe gold catalyst in /ionic liquid was achievedcould be recycled at least five times, affording 2,3-dihydrobenzofuran in good yields.

■ Mn(III)-Based Oxidative Cyclization of 2-((2-Arylamino)ethyl)malonates: Synthesis of Quinolines via Dihydroquinolinedicarboxylates

Takayuki Nagashimada, Masahiro Morikawa, Kengo Ohki, and Hiroshi Nishino*

*Department of Chemistry, Graduate School of Science, Kumamoto University, Kurokami 2-39-1, Kumamoto 860-8555, Japan

Abstract

The synthesis of quinolines from aniline derivatives via the Mn(III)-based oxidative cyclization of 2-(2-(arylamino)ethyl)malonates is described. The 2-(2-(arylamino)ethyl)malonates were prepared in two steps from the substituted anilines. The cyclization of nineteen arylaminoethylmalonates protected by the N-acyl and N-alkoxycarbonyl groups easily proceeded in the formal 6-endo mode regardless of the presence of halo, methyl, and methoxy groups on the aromatic ring, and the corresponding tetrahydroquinolinedicarboxylates were produced in high yields except for the 2,4-dimethoxyphenyl-substituted aminoethylmalonate which occurred by ipso-cyclization. The tetrahydroquinolinedicarboxylate could be transformed into quinoline via decarboxylation and deprotective hydrolysis. The characteristic phenomenon in the NMR spectrum of the tetrahydroquinolinedicarboxylates is also discussed.

■ Synthesis and Blue Dyeing Ability for Polypropylene Fabrics of Various 3,7-Bis(dialkylamino)phenoxazin-5-ium Salts and the Sulfur and Selenium Analogs

Takumi Yoshida* and Masahito Segi*

*Division of Material Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa, Ishikawa 920-1192, Japan

Abstract

3,7-Bis(dialkylamino)phenoxazin-5-ium salts having different amino groups (dimethylamino, diethylamino, dipropylamino, dibutylamino, and pyrrolidyl) and counter anions (chloride, bromide, iodide, hydrogensulfate, and nitrate) were synthesized in up to 80% isolated yield as blue cationic dyes. In addition, 3,7-bis(diethylamino)phenothiazin-5-ium and 3,7-bis(diethylamino)phenoselenazin-5-ium iodides were also synthesized in 20% and 17% isolated yields, respectively. Polypropylene fabrics were dyed with the above synthesized blue cationic dyes. As an evaluation result, it has been found that the moderate size such as diethylamino groups at the 3 and 7 positions of phenoxazinium salts is suitable for the dyeing ability.

■ Preparation of 2-Aryl-3-silyl- and 2-Aryl-3-germyl-1,3-butadienes via Arylnickelation and Zinciomethylation

Nana Yoshino, Betemariam Sharewa, Zenichi Ikeda, and Seijiro Matsubara*

*Department of Material Chemistry, Graduate School of Engineering, Kyoto University, Kyotodaigaku-Katsura, Nishikyo, Kyoto 615-8510, Japan

Abstract

Benzyl 3-silyl(or germyl)propargyl ether, aryl iodide, and bis(iodozincio)methane were assembled in the presence of a nickel catalyst to efficiently give 2-aryl-3-silyl(germyl)-1,3-butadienes via arylnickelation, zinciomethylation, and 1,4-elimination of zinc benzyloxide. As a ligand, an electron-deficient phospine such as tris(2-furyl)phosphine was effective.

■ Synthesis, Structure, and π-Donor Properties of Tris(ethylenedioxy)benzene and Bis(ethylenedioxy)thiophene

Ryoji Watanabe, Tohru Nishinaga,* Yoshiyuki Kuwatani, and Masahiko Iyoda*

*Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan

Abstract

Tris(ethylenedioxy)benzene 3 and bis(ethylenedioxy)thiophene 4 have been synthesized starting from 2,3-dibromo-1,4-dioxene in 25 and 38% overall yields, respectively. These ethylenedioxy-fused benzene and thiophene can be easily oxidized to produce the corresponding radical cations 3•+ and 4•+ because of their high-lying HOMO levels. Interestingly, the radical cation 3•+ exhibits a fairly strong fluorescent emission at λmax 602 and 590 nm (φF = 0.40 in MeCN and 0.50 in H2SO4).

■ Intramolecular Transamidation-Cyclization of N-(α-Oxoacetyl) Diamine: Influence of Solvent, Acidity and Substituents

Takashi Kouko, Hiroaki Miyazawa, Hideki Hikita, Hiromi Totsuka, Kazuhiro Higuchi,* and Tomomi Kawasaki*

*Meiji Pharmaceutical University, 2-522-1 Noshio, Kiyose, Tokyo 204-8588, Japan

Abstract

We studied the selective formation of 3,5- and 2,5-pyrazinone via a transamidation-cyclization reaction. The equilibrium between acyl amides changed depending on the solvent, acidity, and substituents. Furthermore, selective transformation of 2,5-pyrazinone was accomplished by using a substrate with a secondary amine.

■ N-Glycosylation of Thio-glycoside Derived from Odorless Thiols Using Hypervalent Iodine(III) Reagent

Koji Morimoto, Kana Yanase, Tohru Kamitanaka, and Tetsuya Kajimoto*

*School of Pharmacy, Ritsumeikan University, 1-1-1 Noji-higashi, Kusatsu, Shiga, Japan

Abstract

A general and efficient protocol for direct N-glycosylation using inexpensive and readily available thioglycosides prepared from an odorless sulfur source was established. The use of easily available reactants and the mild reaction conditions make this protocol feasible for practical applications.

■ Stereoselective Synthesis of Diastereomeric Berberine Alkaloids, O-Methylcorytenchirine and Coralydine

Misaki Kirii, Junpei Matsuoka, Akari Miyawaki, Kiyoshi Tomioka, and Yasutomo Yamamoto*

*Faculty of Pharmaceutical Sciences, Department of Medicinal Chemistry, Doshisha Women’s College of Liberal Arts, Kodo, Kyotanabe, Kyoto 610-0395, Japan

Abstract

Racemic total synthesis of diastereomeric berberine alkaloids, O-methylcorytenchirine and coralydine, was achieved from the common isoquinoline intermediate of norlaudanosine. The relative stereochemistry of C8-C14 was successfully constructed by favorable axial attack of nucleophiles to the iminium of dihydroprotoberberines.

■ Fasciospyrinadinone and Fasciospyrinadinol, Novel 3-Alkylpyridine Sesquiterpenoids from an Indonesian Marine Sponge, as Selective Growth Inhibitors of the Cancer Cells under Nutrient Starvation

Hirokazu Matsumoto, Tomoya Hisa, Kazunari Toda, Ryosuke Ishida, Andi Setiawan, Masayoshi Arai, and Naoyuki Kotoku*

*College of Pharmaceutical Sciences, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga, 525-8577, Japan

Abstract

On the guidance of the bioassay using PANC-1 cells adapted to the glucose starvation, two novel pyridine sesquiterpenoids named fasciospyrinadinone (1) and fasciospyrinadinol (2) were isolated from the Indonesian marine sponge of Petrosaspongia sp. The chemical structures of the compounds were established on the basis of the 1D and 2D NMR spectra data. Then, we accomplished the first total syntheses of 1 and 2. Compound 1 showed selective growth inhibitory activity against PANC-1 cells adapted to glucose starvation, with IC50 value of 13 µM.

■ A Fluorous Proline Catalyst Immobilized on Teflon® for Highly Stereoselective Asymmetric Aldol Reactions

Kazuki Ishihara, Riho Obayashi, Mizuki Ohira, Yuki Kobayashi, Kotaro Ishihara, Yamato Kato, Narisa Takeuchi, Risa Mizuno, Takayuki Shioiri, and Masato Matsugi*

*Faculty of Agriculture, Meijo University, 1-501 Shiogamaguchi, Tempaku-ku, Nagoya 468-8502, Japan

Abstract

An immobilized fluorous-tagged proline catalyst and its application as a recycling system in highly stereoselective asymmetric aldol reactions is described. The introduction of acidic sulfonamide groups bearing multifluorous tags at the carboxy position proved to be more effective than the introduction of bulky substituents on the proline backbone to achieve high stereoselectivity. The Teflon®-immobilized proline catalyst could be recovered and reused at least five times while maintaining high levels of catalytic activity and stereoselectivity.

■ Divergent Total Synthesis of Azalamellarins D and N

Tsutomu Fukuda,* Seiya Okutani, Mayu Sumi, Kazuhito Miyagi, Gen Onodera, and Masanari Kimura

*Division of Chemistry and Materials Science, Graduate School of Engineering, Nagasaki University, 1-14, Bunkyo-machi, Nagasaki 852-8521, Japan

Abstract

Lamellarins are polycyclic marine alkaloids with potent cytotoxic activities against cancer cell lines. A divergent synthesis of azalamellarins D and N, lactam congeners of the marine natural products lamellarins D and N, has been achieved via the pentacyclic 14-bromo-8,9-dihydro-benzo[7,8]indolizino[3,2-c]- quinolin-6(5H)-one intermediate. The pentacyclic intermediate can be synthesized from methyl 1-(benzensulfonyl)-3-bromo-1H-pyrrole-2-carboxylate via the Suzuki–Miyaura cross-coupling and intramolecular direct arylation as key reactions.

■ Polyfluoroarene-Capped Thiophene Derivatives via Fluoride-Catalyzed Nucleophilic Aromatic Substitution

Kotaro Kikushima, Kana Matsuki, Yuna Yoneda, Takayuki Menjo, Kosuke Kaneko, Tomonori Hanasaki, and Toshifumi Dohi*

*College of Pharmaceutical Sciences, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga, 525-8577, Japan

Abstract

Arylthiophene derivatives are potential components of functional materials, including organic electronics. Herein, we describe a nucleophilic aromatic substitution reaction of polyfluoroarenes using silylthiophenes as nucleophiles in the presence of a catalytic amount of a fluoride salt. Various polyfluoroarene-capped thiophene derivatives were synthesized via double arylation under transition metal-free conditions. A fluoride ion activates a silylthiophene to trigger a nucleophilic aromatic substitution, subsequently affording the coupling product along with elimination of the fluoride ion, which serves as a promoter of the catalytic reaction.

■ Stereoselectivity of the Biginelli Reaction Catalyzed by Chiral Primary Amine: A Computational Study

Takayoshi Yoshimura, Maneeporn Puripat, Vudhichai Parasuk, and Miho Hatanaka*

*Department of Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa 223-8522, Japan

Abstract

The Biginelli reaction catalyzed by a chiral compound is one of the most effective ways to form bioactive heterocycle compounds. High enantioselectivity was obtained using primary amine with a chiral diamine backbone as a chiral catalyst. To elucidate the origin of the enantioselectivity, we investigated the reaction pathways of this catalytic reaction using the density functional theory. We also focused on the transition states of the rate-determining step leading different stereoisomers. The rate-determining step was the proton transfer process accompanying the cyclization of the substrate, which was mediated by the amide moiety of the catalyst, and the orientation of the amide moiety was the reason for the enantioselectivity.

■ Regio-Complementary Preparation of 6- and 7-Fluoro-1,2,3,4-tetrahydroquinolines via the Cyclization of Catecholamines Followed by Deoxyfluorination

Kazuyuki Saito, Wang Zhou, Shohei Sato, Keita Takubo, Kazunori Furutsu, Ahmed A. B. Mohamed, Euis Maras Purwati, Takashi Ikawa, and Shuji Akai*

*Graduate School of Pharmaceutical Sciences, Osaka University, 1-6 Yamada-oka, Suita, Osaka 565–0871, Japan

Abstract

We herein report a regioselective preparation of 6- and 7-fluoro-1,2,3,4-tetrahydroquinolines by applying the deoxyfluorination strategy, developed by the authors. This method includes the cyclization of catecholamines bearing an N-protecting group to form 7-hydroxy-1-azaspiro[4.5]deca-6,9-dien-8-ones and 6,7-dihydroxy-1,2,3,4-tetrahydroquinolines followed by deoxyfluorination, in which the nature of the N-protecting group has a significant effect on both the cyclization and the regioselectivity of the deoxyfluorination reaction.

■ Computational Study for the Aromatic Nucleophilic Substitution of 4-Dimethylamino-3-trifluoroacetyl- quinoline with Various Nucleophiles

Norio Ota, Souma Nakagawa, Yasuhiro Kamitori, and Etsuji Okada*

*Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan

Abstract

The aromatic nucleophilic substitutions of 4-dimethylamino- 3-trifluoroacetylquinoline 1 with amines, thiols, and alcohols are elucidated on the basis of DFT calculations. Our calculation results suggest that the reaction of 1 with amines giving N-N exchanged products 4 occurs via Meisenheimer type adducts V whereas the ones with thiols and alcohols proceed via the enol type adducts VII and IX to afford N-S and N-O exchanged products 8 and 9, respectively. It is also clarified that the conditions required for the successful substitution are not controlled by the activation energies on these processes, but by the energy changes on the processes from 1 to each intermediates, V, VII, and IX.

■ Design and Synthesis of Novel Orexin Antagonists via Structural Simplification of the Morphinan Skeleton

Sayaka Ohrui,* Yoko Irukayama-Tomobe, Yukiko Ishikawa, Masashi Yanagisawa, and Hiroshi Nagase

*C1232 Kanagawa Science Park R & D Building, Research Foundation ITSUU Laboratory, 3-2-1 Sakado, Takatsu-ku, 213-0012 Kawasaki, Kanagawa, Japan

Abstract

Herein, we report novel orexin antagonists with a spiro-type piperidine skeleton designed and synthesized via removal of the unnecessary sites of orexin 1 receptor (OX1R) antagonists with a morphinan skeleton for binding to OX1R. In addition, while decahydroisoquinoline compounds with an A-ring did not show antagonistic activity for OX1R, spiro-type piperidine compounds with a dihydroindene structure showed antagonistic activities. This suggests that the lipophilic site corresponding to the A-ring of the morphinan skeleton is important for determining the antagonistic activity toward OX1R.

■ A Theoretical Study of Product Selectivity in Rhodium Catalyzed Oxidative Coupling Reaction Caused by the Solvation Effect

Masahiro Higashi,* Naoto Shibata, Suguru Takeno, Tetsuya Satoh, Masahiro Miura, and Hirofumi Sato*

*Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Kyoudai-katsura, Nishikyo, Kyoto 615-8510, Japan

Abstract

Solvation effects in the direct oxidative coupling of 1-phenylpyrazole with alkynes in the presence of rhodium catalyst was theoretically studied by means of the reference interaction site model self-consistent field with spatial electron density distribution (RISM-SCF-SEDD) method, which provides both of quantum chemical and statistical mechanical information on the solvation system. This reaction gives naphthalene and quinoline derivatives whose yields depend on the solvent environment. The computational results showed that the path for the naphthalene derivative is exothermic independently of solvent environment. On the other hand, the reaction energy of the reductive elimination for the quinoline derivative is considerably affected by solvation and endothermic in N,N- dimethylformamide (DMF) solution, indicating that the reaction is not preferable in DMF solution. The detailed analysis of solvation free energy and solvation structure are also reported.

■ Stereoselective Synthesis of (2S,3R)- and (2S,3S)- 2-Amino-3-(3,4-dihydroxyphenyl)-3-hydroxypropanoic Acid

Yoko Yasuno, Shunsuke Yamaguchi, Yuma Karita, Kenta Sakai, Hironori Okamura, Atsushi Nakayama, and Tetsuro Shinada*

*Graduate School of Science, Osaka City University, Sugimoto, Sumiyoshi-ku, Osaka 558-8585, Japan

Abstract

(2S,3R)- and (2S,3S)-2-amino-3-(3,4-dihydroxyphenyl)-3-
hydroxypropanoic acids (ADHP) are often found in an unusual amino acid component of phomopsin B, ustiloxins, RA-IV, and MPC1001B. Herein, we would like to report stereoselective synthesis of (2S,3R)- and (2S,3S)-ADHP equivalents for the synthesis of ADHP containing natural products. The synthesis is characterized by the stereocontrolled construction of the (2S,3R)- and (2S,3S)-stereocenters starting from Garner’s aldehyde as a common starting material.