Special Issue

Albert Eschenmoser's Special Issues, Vol. 82, No. 2, 2011

66 data found. 61 - 66 listedFirst Previous
Note | Special issue | Vol 82, No. 2, 2011, pp. 1699 - 1704
Published online: 26th October, 2010
DOI: 10.3987/COM-10-S(E)107
Synthesis of 6-Deoxy-D-altrose Used as an Authentic Sample to Identify an Unknown Monosaccharide Isolated from the Fruiting Body of an Edible Mushroom

Masashi Yamada, Fumi Yoshida, Hiromune Ando, Hideharu Ishida,* Makoto Kiso, and Masakuni Tako

*Faculty of Applied Biological Sciences, Gifu University , 1-1 Yanagido, Gifu, Gifu 501-1193, Japan

Abstract

Here, we describe the synthesis of 6-deoxy-D-altrose and its subsequent use as an authentic sample to verify the structure of a monosaccharide newly isolated from the fruiting body of an edible mushroom. D-Rhamnopyranoside, converted from D-mannopyranoside, was selectively protected to give the 3-OH derivative, which was converted to the corresponding 6-deoxy-D-altropyranoside by nucleophilic substitution of the 3-triflate with acetoxy group. Removal of the protecting group, including the temporary protection of the anomeric position with the THP group, afforded the desired 6-deoxy-D-altrose. Both the NMR data and the [α]D value were identical to the data on the natural product, thus indicating that the recently isolated monosaccharide was 6-deoxy-D-altrose.

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Note | Special issue | Vol 82, No. 2, 2011, pp. 1705 - 1708
Published online: 19th October, 2010
DOI: 10.3987/COM-10-S(E)115
Second Generation Palladium-Catalyzed Cycloalkenylation in Iridoid Lactone Synthesis: Total Syntheses of (±)-Onikulactone and (±)-Mitsugashiwalactone

Megumi Saeki and Masahiro Toyota*

*Department of Chemistry, Graduate School of Science, University of Osaka Prefecture, Sakai, Osaka 593-8531, Japan

Abstract

Type-II iridoid lactones, onikulactone (1) and mitsugashiwalactone (2), were synthesized by employing the second generation palladium-catalyzed cycloalkenylation reaction as the key step.

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Note | Special issue | Vol 82, No. 2, 2011, pp. 1709 - 1717
Published online: 11th November, 2010
DOI: 10.3987/COM-10-S(E)116
Synthesis of Selenohydantoins from Isoselenocyanates and α-Amino Acids

Hajime Maeda,* Koichi Sakata, Masaru Takashima, Tatsuya Watanabe, Nobuteru Mizukami, Mitsunori Honda, and Masahito Segi*

*Chemistry Course, College of Science and Engineering, School of Chemistry, Kanazawa University, Kakuma, Kanazawa, Ishikawa 920-1192, Japan

Abstract

Selenohydantoins were synthesized by the reaction of isoselenocyanates with α-amino acids in high yields. Reaction of isoselenocyanates with β-amino acids gave a six-membered ring compound and acyclic selenoureas.

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Note | Special issue | Vol 82, No. 2, 2011, pp. 1719 - 1726
Published online: 30th September, 2010
DOI: 10.3987/COM-10-S(E)118
Structures of Fukinone Epoxides. Configuration, Conformation, and CD Spectra

Yoshinori Saito and Motoo Tori*

*Faculty of Pharmaceutical Sciences, Tokushima Bunri University, 180 Nishihamabouji, Yamashiro-machi, Tokushima, 770-8514, Japan

Abstract

The configuration and conformation of two diastereoisomeric fukinone epoxides were unambiguously established by NMR (NOESY), CD, and X-ray crystallographic analyses of their derivatives. The data show the absolute configurations of exo α,β-epoxy ketones can be predicted by an octant rule, not by a Reverse Octant Rule.

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Note | Special issue | Vol 82, No. 2, 2011, pp. 1727 - 1737
Published online: 2nd November, 2010
DOI: 10.3987/COM-10-S(E)119
Asymmetric Intramolecular Aldol Reaction Mediated by (S)-N-Substituted-N-(2-pyrrolidinylmethyl)amine to Prepare Wieland-Miescher Ketone

Yuichi Akahane, Kohei Inomata,* and Yasuyuki Endo

*Tohoku Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai 981-8558, Japan

Abstract

New or known N-substituted-N-(2-pyrrolidinylmethyl)amine deriva- tives bearing a variety of alkyl and aryl substituents were easily prepared from N-Boc-proline or N’-Boc-N-(2-pyrrolidinylmethyl)amine. The enantioselectivity of the intramolecular asymmetric aldol reaction mediated by a combination of the amine derivative and TFA to prepare Wieland-Miescher ketone was examined. During the examination, optimal amount of TFA in the reaction was identified.

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Note | Special issue | Vol 82, No. 2, 2011, pp. 1739 - 1745
Published online: 20th January, 2011
DOI: 10.3987/COM-10-S(E)127
Oxidative Coupling of Indoles with 3-Oxindoles

Mikkel Jessing and Phil S. Baran*

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

Abstract

A mild procedure for the union of 3-oxindoles with indoles is reported using oxidative coupling.

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