Special Issue

Steven M. Weinreb's Special Issues, Vol. 70, No. 1, 2006

70 data found. 31 - 60 listedFirst Previous Next Last
Paper | Special issue | Vol 70, No. 1, 2006, pp. 185 - 199
Published online: 20th June, 2006
DOI: 10.3987/COM-06-S(W)3
Strecker Reactions of Chiral N-Acylhydrazones

Hui Ding and Gregory K. Friestad*

*415 Chemistry Building, Department of Chemistry, University of Iowa, 320 North Madison Street, Iowa City, Iowa 52242, U.S.A.

Abstract

Development of a method for addition of trimethylsilyl cyanide to chiral oxazolidinone-derived N-acylhydrazones is described. The diastereoselectivity was found to be highly dependent on the substituent of the oxazolidinone moiety; 4-phenyl-2-oxazolidinone achieved much higher stereocontrol than four other oxazolidinones screened. The reaction gives modest selectivity with aliphatic hydrazones and excellent selectivity with hydrazones prepared from aromatic aldehydes.

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Paper | Special issue | Vol 70, No. 1, 2006, pp. 201 - 205
Published online: 14th July, 2006
DOI: 10.3987/COM-06-S(W)4
Direct Conversion of Substituted Pyrrole-2-carboxylic Acid Methyl Esters to Their 2-Carbonitrile Analogues

Xun Li,* Michael Reuman, and Ronald K. Russell

*US Resarch & Early Development, Johnson & Johnson Pharmaceutical Research & Development, L. L. C., 1000 Route 202, Rartan, New Jersey 08869, U.S.A.

Abstract

Small to large quantity (1-136 g) of substituted pyrrole-2-carbonitrles were reproducibly prepared from their corresponding 2-carboxylic acid methyl esters in one step with 53-61% yield and high chemical purity (>97%), with using dimethylaluminum amide [(CH3)2AlNH2] that was freshly generated by treating anhydrous ammonia (NH3) and trimethylaluminum [(CH3)3Al] at -40 °C in chlorobenzene, a modified Weinreb’s method.

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Paper | Special issue | Vol 70, No. 1, 2006, pp. 207 - 221
Published online: 11th July, 2006
DOI: 10.3987/COM-06-S(W)5
Cycloaddition Reactions of 1-Aza- and 1,3-Diazaazulenium 1-Methylides

Hiroyuki Fujii,* Izumi Kawano, Kaoru Iwafuji, Yoshiyuki Sawae, Kentaro Nagamatsu, and Noritaka Abe*

*Department of Chemistry, Faculty of Science, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8512, Japan

Abstract

2-Chloro-, 2-methoxy-, and 2-amino-1-azaazulenium 1-methylides and 1,3-diazaazulenium 1-methylide were generated by the treatment of the corresponding 1-trimethylsilylmethyl-1-azaazulenium triflates and 1-trimethylsilylmethyl-1,3-diazaazulenium triflate with CsF; the triflates were prepared from the corresponding 1-azaazulenes and 1,3-diazaazulene with trimethylsilylmethyl triflate. The 1,3-dipolar cycloadditions of the 2-chloro-1-azazaazulenium 1-methylide, prepared in situ, with acetylenic esters gave 2a-azabenz[cd]azulene derivatives and 3a-azacyclopenta[a]naphthalene derivatives as major products, whereas 2-piperizino-1-azaazulenium 1-methylide underwent extended dipolar cycloaddition with acetylenic esters and afforded 9b-azacyclopent[a]azulene derivatives as major products.

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Paper | Special issue | Vol 70, No. 1, 2006, pp. 223 - 233
Published online: 29th August, 2006
DOI: 10.3987/COM-06-S(W)12
A De Novo Asymmetric Approach to Achiral Deoxy-Melodorinol Analogues

Md. Moinuddin Ahmed, Novruz Akhmedov, Hu Cui, Dirk Friedrich, and George A. O’Doherty*

*Department of Chemistry, West Virginia University, Morgantown, WV 26506-6045, U.S.A.

Abstract

A short and highly efficient route to deoxy-Melodorinol analogues has been developed. The key to the overall transformation is the use of an enantioselective Sharpless asymmetric dihydroxylation of an (Z,E)-dienoate to control the regioselectivity of the dihydroxylation reaction and a Mitsunobu elimination reaction to control the E-stereochemistry of the γ,δ-double bond. The highly efficient synthesis stereoselectively prepared four analogues in 3 steps from 4-substituted crotonaldehydes.

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Paper | Special issue | Vol 70, No. 1, 2006, pp. 235 - 248
Published online: 29th August, 2006
DOI: 10.3987/COM-06-S(W)11
Pyran-2-ones as Synthons for Pyridazine-3-carboxylic Derivatives. Oxidation of Nitrogen-Rich Compounds

Franc Pozgan, Stanislav Kafka, Slovenko Polanc, and Marijan Kočevar*

*Department of Organic Chemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, Askerceva 5, P.O. Box 537, SI-1000 Ljubljana, Slovenia

Abstract

The reaction of 6-(pyridin-2-yl)-2H-pyran-2-one (1) with hydrazine hydrate toward pyridazine derivatives was investigated. To elucidate the reaction pathway, an intermediary-formed α,β-dihydrazonohydrazide derivative (3) was successfully isolated. Oxidations of the above compounds as well as of other pyridazine derivatives containing a carbohydrazido group, using ammonium cerium(IV) nitrate (CAN), thallium(III) nitrate trihydrate (TTN), or copper(II) acetate hydrate (CuDA), are also presented.

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Paper | Special issue | Vol 70, No. 1, 2006, pp. 249 - 259
Published online: 22nd September, 2006
DOI: 10.3987/COM-06-S(W)15
The Concise and Versatile Synthesis of Epi-malbrancheamide and Structurally Related Analogs

Meriah W. N. Valente and Robert M. Williams*

*Department of Chemistry, Colorado State University, Fort Collins, CO 80523-1872, U.S.A.

Abstract

The synthesis of C-19-epi-malbrancheamide and several structurally related analogs is reported.

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Paper | Special issue | Vol 70, No. 1, 2006, pp. 261 - 270
Published online: 5th September, 2006
DOI: 10.3987/COM-06-S(W)17
Selective 1,2- vs 1,4-Addition of N-Arylphosphazenes to β,γ-Unsaturated α-Ketoesters. Synthesis of Quinolinecarboxylates

Francisco Palacios,* Javier Vicario, Jesús M. de los Santos, and Domitila Aparicio

*Department of Organic Chemistry I, Faculty of Pharmacy, University of The Basque Country, P.O. Box 450, 01080 Vitoria, Spain

Abstract

Selective conjugate reaction (1,4 addition) of N-arylphosphazenes derived from triphenylphosphine to α,β-unsaturated carbonyl compounds yielded 2-quinolinecarboxylates. However, when more reactive phosphazene species derived from trimethylphosphine were used, selective reaction with the carbonyl carbon (1,2-addition) occurred and N-aryl 1-azadienes were obtained. Thermal 6π-azaelectrocyclization of these 1-azadienes afforded 4-quinolinecarboxylates.

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Paper | Special issue | Vol 70, No. 1, 2006, pp. 271 - 278
Published online: 12th September, 2006
DOI: 10.3987/COM-06-S(W)18
Dediastereomerization of Dibenzylbutanolides by Plant Cell Culture

Masumi Takemoto,* Yuki Matsuoka, Kiyoshi Tanaka, and James Peter Kutney

*Schol of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Shizuoka 422-8526, Japan

Abstract

When a mixture of two diastereomers (4R*-3) and (4S*-3) was subjected to plant cell cultures, hydrolysis of acetate and dediastereomerization took place to give a single diastereomer (4R*-1) with 100% diastereomeric excess and 0% enantiomeric excess.

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Paper | Special issue | Vol 70, No. 1, 2006, pp. 279 - 294
Published online: 15th September, 2006
DOI: 10.3987/COM-06-S(W)20
Synthesis of (+)-Myrtopsine, (+)-7,8-Dimethoxymyrtopsine, and Related 2,3-Dihydro-3-hydroxy-2-(1-hydroxy-1-methylethyl)benzofuran Natural Products

Barry B. Snider* and Xiaoxing Wu

*Department of Chemistry, Brandeis University, 415 South Street, Waltham, MA 02254-9110, U.S.A.

Abstract

The first syntheses of myrtopsine (8t) and 7,8-dimethoxymyrtopsine (9t) have been carried out by halogen-metal exchange of 3-iodo-4-methoxyquinolin-2(1H)-ones (15) and (21) with i PrMgCl followed by addition of 3,3-dimethyloxirane-2-carboxaldehyde. A two-step sequence leads selectively to trans-2,3-dihydro-3-hydroxy-2-(1-hydroxy-1-methylethyl)benzofurans (7t), (8t), (9t), (28), and (32) by conversion of a 2-iodophenol or a 3-iodo-4-methoxyquinolin-2(1H)-one to an aryl Grignard reagent and addition of 3-methyl-2-butenal, followed by threo selective epoxidation of the resulting allylic alcohol and cyclization with inversion.

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Paper | Special issue | Vol 70, No. 1, 2006, pp. 295 - 307
Published online: 15th September, 2006
DOI: 10.3987/COM-06-S(W)23
Two Convergent Approaches to the Synthesis of 1α,25-Dihydroxy-2β-(3-hydroxypropoxy)vitamin D3 (ED-71) by the Lythgoe and the Trost Coupling Reactions

Junji Maeyama, Hiroko Hiyamizu, Keisuke Takahashi, Jun Ishihara, Susumi Hatakeyama, and Noboru Kubodera*

*Chugai Pharmaceutical Co., Ltd., 2-1-1, Nihonbashi-Muromachi, Chuo-ku, Tokyo 103-8324, Japan

Abstract

Two convergent syntheses of 1α,25-dihydroxy-2β-(3-hydroxypropoxy)vitamin D3 (ED-71) by the Lythgoe coupling reaction between the A-ring phosphine oxide and the C/D-ring ketone and the Trost coupling reaction between the A-ring ene-yne and the C/D-ring bromomethylene are described.

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Paper | Special issue | Vol 70, No. 1, 2006, pp. 309 - 319
Published online: 7th November, 2006
DOI: 10.3987/COM-06-S(W)24
Synthesis of 2,3-Dihydrobenzo[1,4]dioxins and -oxazins via a Domino Wacker-Heck Reaction

Lutz G. Tietze,* Kristina F. Wilckens, Sinem Yilmaz, Florian Stecker, and Julia Zinngrebe

*Institute of Organic and Biomolecular Chemistry, Georg-August-University, Tammannstr. 2, D-37077 Göttingen, Germany

Abstract

An efficient and operationally simple domino Wacker-Heck reaction of allylic phenols and α,β-unsaturated ketones as well as esters in the presence of catalytic amounts of Pd(TFA)2 and an oxidant for the synthesis of 2,3-dihydrobenzo[1,4]dioxins and 2,3-dihydrobenzo[1,4]oxazins is described. The necessary substrates are prepared by monoallylation of catechol derivatives and ortho-aminophenol.

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Paper | Special issue | Vol 70, No. 1, 2006, pp. 321 - 334
Published online: 10th October, 2006
DOI: 10.3987/COM-06-S(W)28
A Chiral Pool Approach toward the Synthesis of Thalidomide Metabolites

Frederick A. Luzzio,* Damien Y. Duveau, and William D. Figg

*Department of Chemistry, University of Louisville, 2320 South Brook Streeet, Louisville, KY 40292, U.S.A.

Abstract

A synthetic strategy toward the glutarimide-derived metabolite of thalidomide, 5’-hydroxythalidomide (5’-OH THD, 2) was developed which utilizes aspartic acid as a “chiral pool”-type starting material. The synthesis incorporates a Henry reaction as the key carbon-carbon bond-forming step followed by a tandem reduction-cyclization of the intermediate nitroalcohol in forming the heterocyclic core of 5’-OH THD

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Paper | Special issue | Vol 70, No. 1, 2006, pp. 335 - 344
Published online: 17th October, 2006
DOI: 10.3987/COM-06-S(W)29
Enantioselective Synthesis of ent-Sedridine and (+)-Coniine via Proline-Catalyzed Mannich Reaction

Kazuhiro Nagata, Kosuke Nishimura, Masashi Yokoya, and Takashi Itoh*

*School of Pharmaceutical Sciences, Showa University, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo 142-8555, Japan

Abstract

Proline-catalyzed three component Mannich reaction using 5-hydroxypentanal as a substrate was achieved in high enantioselectivity to construct a chiral center at C-2 position of 2-substituted piperidine alkaloids. The method was applied to the total syntheses of ent-sedridine and (+)-coniine.

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Paper | Special issue | Vol 70, No. 1, 2006, pp. 345 - 354
Published online: 6th October, 2006
DOI: 10.3987/COM-06-S(W)32
Dual Fluorescence Spectra of 1-Hydroxyindoles with Various C-C-Nb Side Chains at 3-Position in Methanol

Kunihiro Tokumura,* Akio Hayashi, Kenta Imai, and Masanori Somei*

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

Abstract

Almost the same ultraviolet absorption spectra with a broad peak at 292-294 nm and a shoulder peak at 275 nm were observed for methanol solutions of 1-hydroxyindoles with various C-C-Nb side chains at 3-position such as 1-hydroxy-Nb-methoxycarbonyltryptamine (1), Nb-acetyl-1-hydroxytryptophan methyl ester (2), N,N-dimethyl-1-hydroxyindole-3-acetamide (3), and 1-hydroxy-Nb-pivaloyltryptamine (4). Dual fluorescence excitation and emission spectra resulting from 1La1A and 1Lb1A fluorescence emissions were observed for these 1-hydroxyindoles (1 - 4). Excitation spectra were found to be dependent on observing wavelength of broad fluorescence emission spectra (λmax = 346-350 nm for 1, 2, and 3; λmax = 366 nm for 4). Dual fluorescence behaviors can be explained by the fact that 1La state locates slight below 1Lb state, and it is supported by time-dependent density functional theory calculations of 1 - 4 in methanol. It is noteworthy that dual fluorescence behaviors are delicately modified by C-C-Nb side chain at 3-position of indole ring.

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Paper | Special issue | Vol 70, No. 1, 2006, pp. 355 - 365
Published online: 6th October, 2006
DOI: 10.3987/COM-06-S(W)33
Synthesis of 6- and 7-(1,2,3-Trihydroxy-1,2-O-isopropylidenepropyl)pteridines and Deoxygenation of Their 3’-Hydroxy Groups

Tadashi Hanaya,* Daisuke Takayama, and Hiroshi Yamamoto

*Department of Chemistry, Faculty of Science, Okayama University, 3-1-1 Tsushima-naka, Okayama 700-8530, Japan

Abstract

Treatment of 3,4-O-isopropylidene-L-threo-pentos-2-ulose (7) with 5,6-diamino-1,3-dimethyluracil (8) afforded 1,3-dimethyl-6-[(1R,2S)-1,2,3-trihydroxy-1,2-O-isopropylidenepropyl]lumazine (9a) and its 7-substituted isomer (9b). Deoxygenation of 3’-hydroxy groups of 9a,b was investigated in connection with a practical transformation of neopterin into biopterin.1

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Paper | Special issue | Vol 70, No. 1, 2006, pp. 367 - 388
Published online: 21st November, 2006
DOI: 10.3987/COM-06-S(W)36
Cycloaddition Reactions of Amino-Acid Derived Cross-Conjugated Trienes: Stereoselective Synthesis of Novel Heterocyclic Scaffolds

Branko Mitasev, Bingli Yan, and Kay M. Brummond*

*Department of Chemistry, University of Pittsburgh, Parkman Avenue & University Drive, Pittsburgh, PA 15260, U.S.A.

Abstract

Cross-conjugated trienes obtained via a Rh(I)-catalyzed allenic Alder-ene reaction represent a new class of compounds. The synthesis of heterocyclic compounds containing multiple fused rings was accomplished via sequential Diels-Alder reactions of amino-acid derived cross-conjugated trienes. Newly synthesized imino-oxazolidinone fused trienes were used to control the stereoselectivity in an intermolecular cycloaddition sequence. Additionally, intramolecular cycloaddition of ester tethered tetraene stereoselectively afforded fused tricyclic pyridino-pyranone which was effectively utilized in subsequent cycloaddition reactions.

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Paper | Special issue | Vol 70, No. 1, 2006, pp. 389 - 421
Published online: 1st December, 2006
DOI: 10.3987/COM-06-S(W)37
The Efficient Separation of Lithium Chloride by Acyclic Carrier Molecules

Junko Morita, Shinji Tsuchiya, Misa Ifuku, Makie Kobayashi, Eriko Araki, Zhenxia Zhu, Keiko Takano, and Shojiro Ogawa*

*Center of Environmental Science for Human Life, Ochanomizu University, 2-1-1 Otsuka, Bunkyo-ku, Tokyo 112-8610, Japan

Abstract

A new acyclic carrier molecule (1) (2,9-didodecanoylamino-1,10-phenanthroline) for the separating purpose of lithium chloride was synthesized by a simple, short synthetic route. Carrier (1) exhibited the high selectivity for binding to the Li+ ion, and has enough ability to form a stable complex consisting of one carrier (1) and one Li+ ion. LiCl is separated efficiently from the mixture of various alkali metal chlorides by using liquid membranes containing carrier (1). The transport rate and selectivity by carrier (1) can are changed by the concentration of metal salts and the properties of anion in the source phase. Two different transport mechanisms are proposed for the explanation of this transport result and molecular orbital calculations on two proposed carrier (1)-Li+ complexes provide a possibility of supporting above explanation. The numerical simulation of Li+ transport using the rate equation of a simple model suggests that the transport by carrier (1) is promoted due to the diffusion limited process and this property is similar to other previously reported macrocyclic carrier molecules. These results indicate an important fact that simple, acyclic compounds have enough ability as LiCl carrier, though the complicated macrocycles with small cavity have been known as Li+ ion selective carriers.

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Paper | Special issue | Vol 70, No. 1, 2006, pp. 423 - 459
Published online: 24th October, 2006
DOI: 10.3987/COM-06-S(W)40
Aza-[3+3] Annulations. Part 6. Total Synthesis of Putative (-)-Lepadiformine and (-)-Cylindricine C

Jiashi Wang, Jacob J. Swidorski, Nadiya Sydorenko, Richard P. Hsung,* Heather A. Coverdale, Jennifer M. Kuyava, and Jia Liu

*Department of Chemistry, University of Minnesota, 207 Pleasant Street S. E. Minneapolis, MN 55455-0431, U.S.A.

Abstract

Efforts in achieving an enantioselective total synthesis of (-)-cylindricine C along with the syntheses of putative lepadiformine, epi-lepadiformines, (-)-4-deoxo-cylindricine C, and (-)-2-epi-cylindricine C are described here in details. These syntheses feature a stereoselective intramolecular aza-[3 + 3] annulation as a unified strategy, and specifically, the total synthesis of (-)-cylindricine C was accomplished in 22 steps with a 4.5% overall yield from L-serine. In addition, we developed an interesting halohydrin formation for the construction of the C4-ketone of cylindricines.

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Paper | Special issue | Vol 70, No. 1, 2006, pp. 461 - 476
Published online: 2nd November, 2006
DOI: 10.3987/COM-06-S(W)44
Synthetic Approaches to Polyhydroxy Indolizidines and Related Azabicyclic Scaffolds

Stephen Hanessian,* Eric Therrien, Jayakumar S. Warrier, and Guillaume Charron

*Department of Chemistry, University of Montreal, 2900 Edouard-Montpetit, Montréal, Québec H3C 3J7, Canada

Abstract

Approaches to the synthesis of unnatural polyhydroxylated indolizidines are described. Key reactions involve addition of 2-(trimethylsilyloxy)furan to iminium salts, and ring-closure metathesis as second alternative.

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Paper | Special issue | Vol 70, No. 1, 2006, pp. 477 - 490
Published online: 2nd November, 2006
DOI: 10.3987/COM-06-S(W)47
Synthesis of 1,2,3,4,5,6,7,10-Octahydro-1,5-imino-7,10-dioxo-3-benzazocine-4-carbonitrile Derivative and Evaluation of Antitumor Activity Related to Saframycin and Renieramycin Isoquinolinequinones

Yu-ichi Koizumi, Ken-ichi Inamura, Akinori Kubo, and Naoki Saito*

*Graduate School of Pharmaceutical Sciences, Meiji Pharmaceutical University, 2-522-1 Noshio, Kiyose, Tokyo 204-8588, Japan

Abstract

3-Benzyl-1,2,3,4,5,6,7,10-octahydro-9-methoxy-8,11-dimethyl-7,10- dioxo-1,5-imino-3-benzazocine-4-carbonitrile (4) as a simple model of saframycin A and renieramycin M is prepared and its cytotoxicity tested against three human cancer cell lines.

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Paper | Special issue | Vol 70, No. 1, 2006, pp. 491 - 499
Published online: 24th October, 2006
DOI: 10.3987/COM-06-S(W)48
Synthesis of 6-Methylindole-4,7-quinone and Anti-tumor Activities of Its Related Indolequinones

Junko Nobuhiro, Miho Hirayama, Tominari Choshi, Keiichi Kamoshita, Sakiko Maruyama, Yoshikazu Sukenaga, Takashi Ishizu, Haruto Fujioka, and Satoshi Hibino*

*Graduate School of Pharmacy and Pharmaceutical Sciences, Faculty of Pharmacy and Pharmaceutical Sciences, Fukuyama University, Fukuyama, Hiroshima 729-0292, Japan

Abstract

We synthesized 6-methylindole-4,5-quinone (1b) in order to clarify the structure of natural product, 5-methylindole-4,5-quinone (1a) isolated from Drupella fragum. The synthesis features the construction of the indole ring based on an electrocyclic reaction of a 3-alkenyl-2-propargylpyrrole intermediate.
Two synthetic methylindolequinones and their related compounds were examined in human lung cancer cell line NCI-H460 and human breast cancer cell line MDA-MB-231.

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Paper | Special issue | Vol 70, No. 1, 2006, pp. 501 - 508
Published online: 17th November, 2006
DOI: 10.3987/COM-06-S(W)51
Photochemical Synthesis of Polycyclic Pyrimidines through the Acid Catalyzd Cycloaddition of 6-Chloro-1-methyluracil to Methyl Substituted Benzenes

Kazue Ohkura,* Takeshi Yamaguchi, Ken-ichi Nishijima, Yuji Kuge, and Koh-ichi Seki

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

Abstract

UV-irradiation of 6-chloro-1-methyluracil with benzene in the presence of TFA resulted in 1,2-cycloaddition and susequent elimination of HCl gave a cyclooctapyrimidine-2,4-dione. Similar acid catalyzed photoreaction with substituted benzenes bearing two or three methyl groups afforded the corresponding cyclooctapyrimidines and two novel pentacyclic compounds, 9,11-diazapentacyclo[6.4.0.01,3.02,5.04,8]dodecanes and 9.11-Å@diazapentacyclo[6.4.0.01,3.02,6.04,8]dodcanes, in fair yields.

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Paper | Special issue | Vol 70, No. 1, 2006, pp. 509 - 517
Published online: 24th November, 2006
DOI: 10.3987/COM-06-S(W)54
Synthesis of a Stable Pyridyl Boronate and Its Reaction with Aryl and Heteroaryl Halides

Steven J. Durrant,* Joanne L. Pinder,* Jean-Damien Charrier, Juan-Miguel Jimenez, Guy Brenchley, Philip N. Collier, David Kay, Andrew Miller, Françoise Pierard, Sharn Ramaya, Shazia Sadiq, and Heather C. Twin

*Vertex Pharmaceuticals Limited, 88 Milton Park, Abingdon, Oxfordshire, OX14 4RY, U.K.

Abstract

The synthesis and reaction of a versatile 5-pyridyl boronate is described. This intermediate can be used to synthesize a range of biologically interesting 2-(1H)-pyridones.

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Paper | Special issue | Vol 70, No. 1, 2006, pp. 519 - 530
Published online: 21st November, 2006
DOI: 10.3987/COM-06-S(W)56
Alkylation of 2-Butyl-4,4-dimethyl-4H-benzo[d][1,3]oxathiien-1,1-dioxide, a New Class of Acyl Anion Equivalents as an Alternative to Dithianes

Robert K. Boeckman, Jr.,* Susan M. Hanson, and Jeremy A. Cody

*Department of Chemistry, University of Rochester, University of Rochester, U.S.A.

Abstract

(2-Butyl-4,4-dimethyl-4H-benzo[d][1,3]oxathiine-1,1-dioxide has been found to react with several electrophiles, such as various halides and aldehydes, upon regioselective deprotonation. This method utilizes the sulfone group to form new carbon-carbon bonds while serving as a masked carbonyl. Subsequent hydrolysis of the sulfone provides a facile approach toward many useful synthetic intermediates. This methodology could provide a useful alternative to the use of dithiane groups.

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Note | Special issue | Vol 70, No. 1, 2006, pp. 531 - 540
Published online: 20th June, 2006
DOI: 10.3987/COM-06-S(W)1
A Facile Construction of the Benz[c,d]indole Framework

Clifford E. Soll and Richard W. Franck*

*Department of Chemistry, Hunter College, City University of New York (CUNY), 695 Park Ave., New York, NY 10021, U.S.A.

Abstract

The Bradsher cycloaddition of isoquinolinium salts has been applied to 5-acetaminoisoquinoline. In 3 simple steps: (i) quaternization of isoquinoline N (ii) cycloaddition with electron-rich dienophile (iii) dehydration, the benz[c,d]indole framework is formed.

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Note | Special issue | Vol 70, No. 1, 2006, pp. 541 - 548
Published online: 11th July, 2006
DOI: 10.3987/COM-06-S(W)6
Chiral Synthesis of Poison-Frog Alkaloids 251N and 221K

Naoki Toyoooka,* Zhou Dejun, Hideo Nemoto,* H. Martin Garraffo, Thomas F. Spande, and John W. Daly

*Faculty of Pharmaceutical Sciences, Toyama University, 2630 Sugitani, Toyama, Toyama 930-0194, Japan

Abstract

The chiral synthesis of 8-butyl 5-substituted poison-frog alkaloids 251N and 221K has been achieved, and the relative stereochemistry of natural 251N was determined by the present chiral synthesis.

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Note | Special issue | Vol 70, No. 1, 2006, pp. 549 - 555
Published online: 12th September, 2006
DOI: 10.3987/COM-06-S(W)10
Biaryl Coupling Reactions of 3-Methoxy-N-(2-iodophenyl)-N-methylbenzamide and 3-Methoxycarbonyl-N-(2-iodophenyl)-N-methylbenzamide Using Palladium Reagent

Hiromi Nishioka,* Chie Nagura, Hitoshi Abe, Yasuo Takeuchi, and Takashi Harayama*

*Faculty of Pharmaceutical Sciences, Okayama University, 1-1-1 Tsushima-naka, Okayama 700-8530, Japan

Abstract

We examined palladium-assisted biaryl coupling reactions of 3-methoxy and 3-methoxycarbonyl benzanilides, and propose an aspect of the mechanism involved in forming a biaryl bond using Pd reagent.

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Note | Special issue | Vol 70, No. 1, 2006, pp. 557 - 570
Published online: 1st September, 2006
DOI: 10.3987/COM-06-S(W)16
Evaluation of Strategies for the Synthesis of the Guanidine Hemiaminal Portion of Palau’amine

Brian A. Lanman and Larry E. Overman*

*Department of Chemistry, University of California, Irvine, 516 Rowland, Irvine California 92697, U.S.A.

Abstract

Potential methods for the generation of the guanidine hemiaminal functionality of palau’amine (1) from a spirocyclic thiohydantoin precursor are examined using a spirobicyclic model system, culminating in the identification of an efficient means of effecting this transformation.

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Note | Special issue | Vol 70, No. 1, 2006, pp. 571 - 580
Published online: 2nd November, 2006
DOI: 10.3987/COM-06-S(W)25
A Facile Synthesis of 2-Acyl and 2-Alkylaminobenzimidazoles for 5-Lipoxygenase Inhibitors

Jin Ha Lee, Mi Hyun Ahn, Eun Hyun Choi, Hea-Young Park Choo, and Gyoonhee Han*

*Department of Biotechnology, College of Engineering, 134 Shinchon-dong, Seodaemun-gu, Seoul 120-749, Korea

Abstract

2-Acylaminobenzimidazoles (2a-r) have been synthesized from o-phenylenediamines (4) with benzoylcarbonimidodithioic acid dimethyl ester (5a) or dimethyl isobutyrylcarbonimidodithioic acid dimethyl ester (5b) in good yield. 2-Alkylaminobenzimidazoles could be prepared by the reaction of o-Phenylenediamines (4a, b) with benzyl isothiocyanate in moderate yields 8a, b or the reaction of 2-chlorobenzimidazole (9) with benzylamines (10a, b) in moderate yield 11a, b. Finally, the carbamate derivative of 2-aminobenzimidazole (13) was prepared by the reaction with pseudourea (12) in low yield. Most of the prepared analogues were evaluated in leukotriene inhibition assay and it found that benzamide derivatives (2a-i) are quite active among others.

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Note | Special issue | Vol 70, No. 1, 2006, pp. 581 - 586
Published online: 29th September, 2006
DOI: 10.3987/COM-06-S(W)27
One-Step Syntesis of 4,5-Disubstituted Pyrimidines Using Commercially Available and Inexpensive Reagents

Phil S. Baran,* Ryan A. Shenvi, and Steven A. Nguyen

*Department of Chemistry, The Scripps Research Institute, 10550 N. Torrey Pines Road, BCC-169, La Jolla, CA 92037, U.S.A.

Abstract

4,5-Disubstituted pyrimidines are synthesized from the corresponding ketone in one-step using inexpensive reagents (formamidine acetate, n-propanol, heat). Contrasted to other methods, this process appears quite amenable to large-scale use in industrial settings.

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