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Regular & Special Issues

27 data found. 1 - 27 listed

Published online: 23rd February, 2018

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(T)27
Oxidative Rearrangement of Benzylamines To 4H-3,1-Benzoxazines via Cu/Mn-Promoted Intramolecular C–H Amination/Electrocyclic Reaction Cascade

Chiaki Yamamoto, Kazutaka Takamatsu, Koji Hirano,* and Masahiro Miura*

*Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan

Abstract

We have developed a copper/manganese-mediated oxidative rearrangement of benzylamines to 4H-3,1-benzoxazines of potent interest in medicinal applications. The reaction proceeds uniquely through the initial copper/manganese-promoted intramolecular C–H amination giving benzazetidine intermediates and subsequent 4π electrocyclic ring opening/6π electrocyclic ring closing cascade. The key to success is the introduction of picolinamide-based N,N-bidentate directing group. The obtained benzoxazines can also be readily hydrolyzed to the corresponding 2-aminobenzyl alcohols, thus indicating that the overall transformations is regarded as the ortho-aminative rearrangement of benzylamines to benzylic alcohols.

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Published online: 22nd February, 2018

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(T)23
Phosphinic Acid-Promoted Addition of Isocyanides to 1-Methoxyisochroman Derivatives

Takahiro Soeta,* Syunsuke Matsuzaki, and Yutaka Ukaji*

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

Abstract

A synthetic method for preparation of isochroman-1-carboxylamides in good to high yields by addition of isocyanides to 1-methoxyisochroman derivatives in the presence of phosphinic acid was developed. A wide range of 1-methoxyisochroman derivatives and isocyanides were suitable for this reaction.

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Published online: 21st February, 2018

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(T)24
Formal Total Synthesis of (±)-Strictamine

Keigo Sato, Noriyuki Takanashi, Noriyuki Kogure, Mariko Kitajima, and Hiromitsu Takayama*

*Graduate School of Pharmaceutical Sciences, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8675, Japan

Abstract

A formal total synthesis of an akuammiline-type indole alkaloid, (±)-strictamine, which features ozonolysis, the Staudinger reaction, and the aza-Wittig reaction to construct its D-ring, is reported.

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Published online: 21st February, 2018

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-17-13864
A Practical Synthesis of the Cyclic Butylene Terephthalate Trimer

Xiaolin Li, Pu Zhou, Wenxuan Wu, Li Zhan, Ting Liu, Fan Yang, Jie Tang, Shanbao Yu, Hui Li, and Yu Luo*

*Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, School of Chemistry and Molecular Engineering, East China Normal University, Shanghai 200241, China

Abstract

This paper described a practical synthetic approach for the cyclic butylene terephthalate trimer (7). The key step was a ring-closing metathesis, using Grubbs’ second-generation catalyst to form the macrocyclic ring. The advantages of this procedure included short reaction steps, simple operations and good yields.

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Published online: 21st February, 2018

Paper | Regular issue | Prepress
DOI: 10.3987/COM-17-13865
A Short-Step Synthesis of Onychine and the Related 4-Azafluorenones via Hetero Diels-Alder Reaction of 5-Substituted Isotellurazoles

Yusuke Taneichi, Kazuaki Shimada,* and Toshinobu Korenaga

*Department of Chemistry and Biosciences, Faculty of Science and Engineering, Iwate University, Iwate 020-8551, Japan

Abstract

Synthesis of onychine and the related 4-azafluorenones was achieved from 5-substituted isotellurazoles through a two-step procedure involving hetero Diels-Alder reaction with methyl phenylpropiolate and the subsequent Friedel-Crafts ring closure of the resulting pyridine derivatives.

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Published online: 20th February, 2018

Paper | Regular issue | Prepress
DOI: 10.3987/COM-17-13862
Novel One-Pot Synthesis of Dihydroacenaphtho[1,2-f][1,3]oxazepines via 1,4-Dipolar Cycloaddition Reaction

Mervat S. Sammor, Mustafa M. El-Abadelah,* Ahmad Q. Hussein, and Firas F. Awwadi

*Department of Chemistry, Faculty of Science, The University of Jordan, Amman 11942, Jordan

Abstract

A facile three-component reaction involving 3-alkyl(aryl)imidazo[1,5-a]pyridines 7a-g, dimethyl acetylenedicarboxylate 2 (DMAD) and acenaphthene-1,2-dione 5 led to the construction of the respective dihydroacenaphtho[1,2-f][1,3]oxazepinedicarboxylates 10a-g in fair yields. Structures of the latter tetracyclic adducts, are based on NMR and MS spectral data and confirmed by single-crystal X-ray diffraction analysis for compound 10a. Most logically, the reaction proceeds via initial formation of the relevant diastereomeric spiro[1,3]oxazine-1,4-dipolar cycloadducts 12, 13 which then suffer skeletal rearrangement leading to the respective acenaphtho[1,2-f]-[1,3]oxazepines 10a-g.

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Published online: 15th February, 2018

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-17-13839
Synthesis of the Anti-Prostate Cancer Drug Abiraterone Acetate

Siyue Ma, Jianheng Li,* Huayang Tang, and Feng Xu

*School of Pharmacy, Hebei University, No.180 WuSi Road, Baoding, 071002, China

Abstract

Abiraterone acetate is used for the treatment of castration-resistant prostate cancer. Abiraterone acetate was synthesized from dehydroepiandrosterone via a three-step reaction including the formation of tosylhydrazone, cross-coupling reaction and acetylation, and a two-step purification including column chromatography and recrystallization with an overall yield of 51.9%. Here, an improved procedure for the preparation of abiraterone acetate is described. This synthetic process is of easy operation and low cost, which is suitable for industrialization.

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Published online: 14th February, 2018

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(T)20
Synthesis and Properties of Oligonucleotides Containing 3′-O,4′-C-Ethyleneoxy-bridged 5-Methyluridines

Takashi Osawa, Yuka Hitomi, Sawako Wakita, Han Kim, Masakazu Dohi, Masahiko Horiba, Yuta Ito, Satoshi Obika, and Yoshiyuki Hari*

*Faculty of Pharmaceutical Sciences, Tokushima Bunri University, Yamashiro-cho, Tokushima 770-8514, Japan

Abstract

A phosphoramidite of 3ʹ-O,4ʹ-C-ethyleneoxy-bridged 5-methyluridine (3ʹ,4ʹ-EoNA-T) was successfully incorporated into oligonucleotides, and their abilities to form duplexes with RNA and DNA as well as triplexes with double-stranded DNA were evaluated. The stabilities of the duplexes formed between RNA and 3ʹ,4ʹ-EoNA-modified oligonucleotides were only slightly lower than those of the natural DNA–RNA duplex, while the duplexes formed between 3ʹ,4ʹ-EoNA-modified oligonucleotides and DNA were drastically less stable than the natural DNA–DNA duplex. Moreover, under the same conditions as the UV-melting experiments of the duplexes, 3ʹ,4ʹ-EoNA-modified oligonucleotides were unable to form triplexes with dsDNA. These results showed that oligonucleotides containing 3ʹ,4ʹ-EoNA-T had excellent RNA selectivity.

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Published online: 13th February, 2018

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-17-13858
Synthetic Studies of Yessotoxin: Stereoselective Annulation of the CD and JK Ring Fragments by Using Pd(II)-Catalyzed Cyclization

Hajime Yokoyama,* Genki Moriyama, Kazuki Nishida, Yasuhiro Kusumoto, Kiyoshi Tsuge, Masahiro Miyazawa, and Yoshiro Hirai

*Department of Chemistry, Graduate School of Science and Engineering, University of Toyama, 3190 Gofuku, Toyama 930-8555, Japan

Abstract

Yessotoxin is the polycyclic ether implicated in diarrheic shellfish poisoning. This toxin has A-K ring system involving 6-, 7-, 8-membered ether rings. We have been studying high stereoselective Pd(II)-catalyzed cyclization. Herein we describe the CD and JK ring fragments of yessotoxin by our annulation based on Pd(II)-catalyzed cyclization. The efforts to understand these high stereoselectivities are also disclosed. This annulation method could be applicable to other polyethers and related natural products.

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Published online: 9th February, 2018

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(T)18
Stereoselective Synthesis of a Pivotal Chiral Intermediate for Natural Salicylic Macrolides

Yoshihito Oguma, Nozomi Yamamoto, Kenji Sugimoto, and Yuji Matsuya*

*Graduate School of Medicine and Pharmaceutical Sciences for Research, University of Toyama, Sugitani 2630, Toyama, 930-0194, Japan

Abstract

As a part of our ongoing research projects on the synthesis of natural salicylic macrolides, the optically active protected salicylate bearing the chiral diene substituent was required as a pivotal synthetic intermediate. The synthesis of the compound was achieved with a high optical purity starting from D-mannitol through Heck coupling reaction and terminal methylenation as key C–C bond forming reactions.

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Published online: 9th February, 2018

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-17-S(T)12
Synthesis Of 2′(2′,6′)-(Di)Halogenoisoxazolopodophyllic Acids-Based Amides Derived from a Naturally Occurring Lignan Podophyllotoxin and their Acaricidal Activity

Bingchuan Zhang, Mingqiao Yu, and Hui Xu*

*Laboratory of Pharmaceutical Design & Synthesis, College of Life Sciences, Northwest A & F University, Xinong Road 22#, Yangling, Shaanxi, 712100, China

Abstract

In continuation of our program to discover natural product-based pesticides, a series of 2′(2′,6′)-(di)halogenoisoxazolopodophyllic acids-based amides were prepared by structural modification of a naturally occurring lignan podophyllotoxin. Meanwhile, their acaricidal activity was evaluated against a typically crop-threatening agricultural insect pest, Tetranychus cinnabarinus. Among all derivatives, especially compounds 1012 displayed 4.8-7.4 folds more potent acaricidal activity than podophyllotoxin against T. cinnabarinus. This demonstrated that the carboxyl group at their C-2 position of 2′(2′,6′)-(di)halogenoisoxazolopodophyllic acids was very important for the acaricidal activity.

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Published online: 7th February, 2018

Short Paper | Regular issue | Prepress
DOI: 10.3987/COM-17-13776
Prins Reaction Using Trioxane for Trisubstituted, cis-Fused Hexahydro-2H-furo[3,2-b]pyran Derivative

Oriel Hlokoane, Hiyori Itagaki, Manami Chiba, Taiki Noda, Yuichi Takasaki, Kei Miyako, Ryuichi Sakai, Yuichi Ishikawa,* and Masato Oikawa*

*Graduate School of Nanobioscience, Yokohama City University, Seto 22-2, Kanazawa-ku, Yokohama 236-0027, Japan

Abstract

The construction of cis-fused heterobicyclic system involved in neuroactive natural products such as dysiherbaine has been accomplished by employing Prins strategy using 1,3,5–trioxane as an equivalent for formaldehyde. The reactions allowed stereoselective construction of the trisubstituted cis-fused hexahydro-2H-furo[3,2-b]pyran with maximum yield of 60%.

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Published online: 7th February, 2018

Communication | Special issue | Prepress
DOI: 10.3987/COM-17-S(T)15
Radical Cyclizations of Aryl Bromides for Synthesis of Cyclopenta[b]Indoles from Vince Lactam

Takumi Abe,* Tsuyoshi Morita, and Koji Yamada

*Faculty of Pharmaceutical Sciences, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido 061-0293, Japan

Abstract

Radical cyclizations of aryl bromides, synthesized in two steps from Vince lactam, afforded cyclopenta[b]indoles in good yields. Furthermore, an unprecedented method for constructing cyclopenta[b]indoles utilizing tricyclic intermediate was also explored.

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Published online: 6th February, 2018

Review | Regular issue | Prepress
DOI: 10.3987/REV-17-877
Enantioselective Heterocycle Formation Using Chiral Hypervalent Iodine(III)

Morifumi Fujita*

*Graduate School of Material Science, University of Hyogo, 3-2-1 Kohto, Kamigori, Ako-gun, Hyogo 678-1297, Japan

Abstract

The field of chiral hypervalent iodine chemistry has made significant progress in the past decade. This review focuses on enantioselective heterocycle formation induced by chiral hypervalent iodine reagents and catalysts. The enantioselective heterocyclizations are classified into the dearomatization of phenols (and naphthols), α-oxidation of carbonyl compounds, and oxidative vicinal difunctionalization of alkenes. As a characteristic reaction of a hypervalent iodine oxidizing reagent, the 6-endo selective lactonization of ortho-alkenylbenzoate is selected and compared with the 5-exo selectivity induced by other electrophilic reagents. The oxidative lactonization with 6-endo selectivity afforded a 4-oxyisochroman-1-one framework, which has been found in a family of polyketide metabolites. The total syntheses of 4-oxyisochroman-1-one natural products were also summarized to assess the synthetic utility of hypervalent iodine compounds

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Published online: 6th February, 2018

Review | Regular issue | Prepress
DOI: 10.3987/REV-17-872
4-Hydroxy-6-methyl-2-pyrone: A Versatile Synthon in the Synthesis of Heterocyclic Scaffolds via Multicomponent Reactions

Ghodsi Mohammadi Ziarani,* Razieh Moradi, Marziyeh Zandiyeh, and Negar Lashgari*

*Department of Chemistry, Alzahra University, Tehran, Iran

Abstract

4-Hydroxy-6-methyl-2-pyrone has been utilized in the synthesis of various heterocyclic compounds. It is a potential 1,3-dicarbonyl compound with diverse synthetic applications that have been extensively investigated. There is a wide range of multicomponent reactions that include 4-hydroxy-6-methyl-2-pyrone in the synthesis of heterocyclic compounds. This review highlights the advances in the use of this compound as starting material in the synthesis of various organic compounds.

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Published online: 2nd February, 2018

Paper | Special issue | Prepress
DOI: 10.3987/COM-18-S(T)19
Total Synthesis of Phenanthroquinolizidine Alkaloid Cryptopleurine and Phenanthroindolizidine Alkaloid Tylophorine

Yousuke Yamaoka,* Marie Taniguchi, Ken-ichi Yamada, and Kiyosei Takasu*

*Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida-shimoadachi-machi, Sakyo-ku, Kyoto 606-8501, Japan

Abstract

Total synthesis of phenanthroquinolizidine alkaloid cryptopleurine was achieved in 11 steps from commercially available 6-bromoveratraldehyde. The crucial step of phenanthrene construction is a formal [2 + 2] cycloaddition of 2-acyl-2’-vinyl-1,1'-biaryl, followed by an acid promoted ring-contraction/ring-opening sequence. The key point to complete the total synthesis of cryptopleurine is use of nosyl amide as a nucleophile for cyclization of piperidine ring. The synthesis of tylophorine was also achieved in the similar manner.

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Published online: 2nd February, 2018

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-17-S(T)13
One-pot Synthesis of (Z)-N-Substituted Isobenzofuran-1(3H)-Imines from Secondary Benzothioamides and Carbonyl Compounds

Kazuhiro Kobayashi* and Takashi Nogi

*Applied Chemistry Field, Chemistry and Biotechnology Course, Department of Engineering, Graduate School of Sustainability Science, Tottori University, 4-101 Koyama-minami, Tottori 680-8552, Japan

Abstract

An efficient one-pot methodology for the synthesis of (Z)-N-substituted isobenzofuran-1(3H)-imines starting from secondary benzothioamides has been developed. The reaction of the starting materials with two equivalents of butyllithium generated 2,N-dilithio-N-alkyl(or aryl)benzothioamides, which were then allowed to react with carbonyl compounds to give, after aqueous treatment, the desired products in satisfactory yields.

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Published online: 26th January, 2018

Paper | Special issue | Prepress
DOI: 10.3987/COM-17-S(T)14
Activation of 1-Methyl-5-Nitro-2-Pyrimidinone by Dearomatization using a Secondary Amine

Haruyasu Asahara, Azusa Yasuoka, and Nagatoshi Nishiwaki*

*School of Environmental Science and Engineering, Kochi University of Technology, Tosayamada-cho, Kami, Kochi, 782-8502, Japan

Abstract

Electron-deficient 1-methyl-5-nitro-2-pyrimidinone is easily attacked by methanol or pyrrolidine to afford the corresponding adducts, respectively, by which aromaticity of nitropyrimidinone is lost. Indeed, the amine-adduct exhibited higher reactivity than that of original structure to facilitate the reaction with 1,3-dicarbonyl compound leading to diazabicyclic compound at room temperature. The amine-adduct also underwent the ring opening reaction to furnish nitroenamines with (Z)-configuration.

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Published online: 23rd January, 2018

Communication | Special issue | Prepress
DOI: 10.3987/COM-17-S(T)9
Fine Chemicals from a Biomass-Derived Dicarboxylic Acid: Chiral Bisoxazolines and Their Application in Enantioselective Diels-Alder Reactions

Sermadurai Selvakumar, Alisa Fairweather, Angel Ugrinov, and Mukund P. Sibi*

*Department of Chemistry, North Dakota State University, Fargo, North Dakota, 58105-5516, U.S.A.

Abstract

2,5-Furandicarboxylic acid (FDCA) is a feedstock chemical readily available from cellulosic biomass. Six chiral bisoxazolines varying in the steric size of the blocking group have been synthesized from FDCA in modest to good overall yields. The effectiveness of the new chiral bisoxazolines has been evaluated in enantioselective Diels-Alder reactions.

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Published online: 23rd January, 2018

Paper | Special issue | Prepress
DOI: 10.3987/COM-17-S(T)11
Research on Unique Masked ortho-Benzoquinone, Monohemiaminal: Synthesis and Reactions

Yuri Matsumoto, Akihiko Nakamura, Emi Saito, and Masahisa Nakada*

*Department of Chemistry and Biochemistry, School of Advanced Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan

Abstract

Synthesis of ortho-benzoquinone monohemiaminals via the oxidative dearomatization/O-cyclization cascades of phenols bearing an ortho substituent derived from an amino alcohol with PIDA is described. The cascade reactions of substrates bearing a chiral substituent were found to proceed in a stereoselective manner. The Diels-Alder reactions of the ortho-benzoquinone monohemiaminals proceed in a highly stereoselective manner. The oxidative dearomatization/O-cyclization cascade affording the ortho-benzoquinone monohemiaminal had never been reported; hence, there is still ample scope for further investigation.

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Published online: 23rd January, 2018

Communication | Special issue | Prepress
DOI: 10.3987/COM-17-S(T)10
Synthesis of 6/6/6-Tricyclic Ether System via Achmatowicz and Intramolecular Oxa-Michael Reactions

Hiroki Yamamoto, Kohei Torikai, Makoto Ebine, and Tohru Oishi*

*Department of Chemistry, Faculty and Graduate School of Science, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan

Abstract

Synthesis of 6/6/6-tricyclic ethers possessing 1,3-diaxial methyl groups was examined via Achmatowicz reaction and intramolecular oxa-Michael reaction. A key precursor was prepared via coupling of an aldehyde with a furyllithium derivative followed by radical deoxygenation of the resulting secondary alcohol. The intramolecular oxa-Michael reaction proceeded in a stereoselective manner to afford cis-fused product as a single isomer.

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Published online: 28th December, 2017

Communication | Special issue | Prepress
DOI: 10.3987/COM-17-S(T)7
Enantioselective Cycloadditions between Aliphatic Nitrile Oxides and 2-Hydroxystyrenes Catalyzed by Chiral Amine-Urea

Yasunori Toda, Masato Koyama, Hiroyoshi Esaki, Kazuaki Fukushima, and Hiroyuki Suga*

*Department of Materials Chemistry, Faculty of Engineering, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553, Japan

Abstract

Chiral amine-urea-catalyzed enantioselective 1,3-dipolar cycloadditions of nitrile oxides with 2-hydroxy-3-methoxystyrene are described. Aliphatic aldehyde-derived hydroximoyl chlorides were used as nitrile oxide precursors, providing optically active isoxazolines with moderate to good enantioselectivities.

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Published online: 26th December, 2017

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-17-S(T)8
Stereoinversion of a Tertiary Alcohol on a THP Ring: a Recovery Route to an Intermediate for Gymnocin-A

Takeo Sakai, Kayo Aoyama, Rie Oshima, Kyoko Furukawa, and Yuji Mori*

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

Abstract

The stereoinversion of a tertiary alcohol on a tetrahydropyran ring was achieved through a five-step sequence including regioselective dehydration, diastereoselective epoxidation and reduction. This approach offers a recovery route from the diastereomer to the desired tertiary alcohol as part of the synthesis of gymnocin-A.

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Published online: 19th December, 2017

Short Paper | Special issue | Prepress
DOI: 10.3987/COM-17-S(T)6
Concise Approach to Mono- and Disubstituted Luotonin A Analogs and Their Cytotoxicity Test

Natsuko Kagawa,* Kimiko Nishimura, Shinya Abe, Takashi Masuko, and Masahiro Toyota*

*Department of Chemistry, Graduate School of Science, Osaka Prefecture University, 1-1 Gakuencho, Sakai, Osaka 599-8531, Japan

Abstract

A concise approach for the preparation of luotonin A analogs has been developed. The new synthetic route contains an anion-assisted intramolecular double hetero Diels ̶ Alder reaction and a direct oxidative cross coupling reaction. Some synthetic luotonin A analogs show cytotoxic activities against Daudi and Jurkat human cancer cells as potent as camptothecin.

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Published online: 18th December, 2017

Paper | Special issue | Prepress
DOI: 10.3987/COM-17-S(T)2
Synthesis of Substituted t-Butyl 3-Alkyl-oxindole-3-carboxylates from Di-t-Butyl (2-Nitrophenyl)malonates

Yusuke Yamai, Akio Tanaka, Tatsuo Yajima, Kyoji Ishida, Itaru Natsutani, Shinichi Uesato, Yasuo Nagaoka, and Takaaki Sumiyoshi*

*Faculty of Chemistry, Materials and Bioengineering, Kansai University, 3-3-35 Yamate-cho, Suita, Osaka 564-8680, Japan

Abstract

Using a novel tandem reduction-cyclization, we synthesized t-butyl 3-alkyloxindole-3-carboxylates from the di-t-butyl 2-alkyl-2-(2-nitrophenyl)-malonate. Introduction of an α-substituent to the di-t-butyl 2-(2-nitrophenyl)-malonates and addition of acid promoted reactivity. This methodology was successfully applied to gram-scale-synthesis of the t-butyl 3-methyloxindole-3-carboxylate 1 and 3-hydroxymethyl-3-methyloxindole 2 without silica gel column chromatography.

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Published online: 17th November, 2017

Paper | Special issue | Prepress
DOI: 10.3987/COM-17-S(T)1
Asymmetric Total Synthesis and Structure Confirmation of (+)-(3E)-Isolaurefucin Methyl Ether

Te-ik Sohn, Byungsook Kim, Deukjoon Kim,* and Robert S. Paton

*The Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Shillim-Dong, San 56-1, Kwanak-Gu, Seoul 151-742, Korea

Abstract

An asymmetric total synthesis and structure confirmation of (+)-(3E)-isolaurefucin methyl ether (2a) was accomplished. Our synthesis features two complementary routes to construct the α,α’-trans-2,8- dioxabicyclo[5.2.1]decane skeleton of the natural product from α,α’-trans-γ,δ-unsaturated oxocene alcohol 7, namely, an intramolecular epoxide opening route and a novel methoxyetherification route based on organoselenium- mediated oxonium ion formation/fragmentation. A computational analysis was performed to model the observed different fragmentation behaviors of the respective oxonium ions 8 and 8’ derived from α,α’-trans- and α,α’-cis-γ,δ-unsaturated oxocene alcohols 7 and 7’ during the organoselenium-mediated oxonium ion formation/fragmentation. Regarding the possibility of the natural product being an artifact, the reactivity of chlorofucin surrogate 16 and neoprelaurefucin surrogate 16’ during methanolysis was compared, the results were in good agreement with calculations.

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Published online: 17th November, 2017

Paper | Special issue | Prepress
DOI: 10.3987/COM-17-S(T)3
Polymeric Silver(I) Complexes Based on Bidentate Imidazoline-2-thiones Synthesis and Crystal Structures

Barbara Rietzler, Gerhard Laus, Klaus Wurst, Thomas Gelbrich, Sven Nerdinger,* Erwin Schreiner, and Herwig Schottenberger

*Sandoz GmbH, Biochemiestrasse 10, 6250 Kundl, Austria

Abstract

The bidentate ligand 1,6-bis(1-methylimidazol-2-ylthio)hexane or its hexafluoride salt reacted with silver(I) triflate, nitrate or oxide, respectively, to give the corresponding polymeric silver(I) complexes. Three crystal structures have been determined and showed linear and cyclic motifs.

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27 data found. 1 - 27 listed