巻号一覧
63 巻, 3 号
選択された号の論文の6件中1～6を表示しています
- |<
- <
- 1
- >
- >|
-
小林 雄一2005 年 63 巻 3 号 p. 190-199
発行日: 2005/03/01
公開日: 2009/11/13
ジャーナル フリーTotal syntheses of macrosphelides published up to August, 2004 are described in the following order : (1) lactonization at the three possible ester linkages; (2) interconversion between macrosphelides A and B; (3) preparation of the segments and the total synthesis via lactonization; (4) the synthesis based on the furan ring cleavage reaction to furnish 4-oxo-2-alkenoic acids; (5) the syntheses through metathesis and carbonylation.抄録全体を表示PDF形式でダウンロード (1299K) -
中川 昌子, 長田 敏明, 小野 宏司, 西田 篤司2005 年 63 巻 3 号 p. 200-210
発行日: 2005/03/01
公開日: 2009/11/13
ジャーナル フリーManzamine alkaloid, (-) -nakadomarin A (1) was first isolated from the Okinawan marine sponge in 1997. Its structure consists of an unprecedented hexacyclic ring system (8/5/5/5/15/6) that includes a furan ring. We report here the first total synthesis of both enantiomers of nakadomarin A.
The spiro-lactam 29, obtained from methyl 4-oxopiperidine carboxylate, was coupled with a furan ring by Suzuki-Miyaura reaction to give intermediate 30. Intramolecular cyclization of the furan ring to acyliminium cation afforded the central core of nakadomarin A, 32. Both 8- and 15-membered rings were constructed by ring closing metathesis (RCM) to give dioxonakadomarin A, 14 which was reduced to (±) -1. Using chiral 23, obtained by optical resolution, the asymmetric synthesis of unnatural enantiomer, (+) -1 has been accomplished and the synthesis confirmed the absolute stereochemistry of (-) -1.
A central ABD ring system 52, which has all stereocenters of (-) -1, was synthesized from chiral hydroisoquinolinone 49, derived from Diels-Alder reaction of chiral piperidinone 47 and siloxydiene 48. The intermediate 52 was converted to natural (-) -nakadomarin A by furan formation via endoperoxides followed by RCM.抄録全体を表示PDF形式でダウンロード (1631K) -
石塚 智也, 古田 弘幸2005 年 63 巻 3 号 p. 211-221
発行日: 2005/03/01
公開日: 2009/11/13
ジャーナル フリーUnusual α and β' linkage of the pyrrole rings (confusion) in porphyrinoids affords a new family of porphyrin analogs having unique physical properties, reactivity and metal-coordination chemistry. Since the finding of N-confused porphyrin (NCP), an isomer of porphyrin, in 1994, various confused porphyrinoids and their metal complexes, including multiply N-confused, hetero-atom substituted, and ring expanded ones, have been synthesized, successively. Confused porphyrinoids reveal a lot of interesting properties, such as NH tautomerism, inner- and outer-metal coordination, organometallics nature, multiple redox system, extended aromatic π-system, etc. In this article, recent development of the confused porphyrinoids is summarized.抄録全体を表示PDF形式でダウンロード (1769K) -
筧 昭一2005 年 63 巻 3 号 p. 222-231
発行日: 2005/03/01
公開日: 2009/11/13
ジャーナル フリーIt is well known that pyridinium N-ylides and their relating pyridinium salts are very useful precursors for the syntheses of some nitrogen-bridged heterocycles, especially, indolizine and pyrazolo [1, 5-a] pyridine. The conventional preparative methods such as the 1, 3-dipolar cycloaddition and the 1, 5-dipolar cyclization of pyridinium N-ylides, and Tschitschibabin reactions of 1-acylmethyl-2-alkyl or aralkylpyridinium salts are convenient to the syntheses of their derivatives, but the compounds obtained thus are helpless for further transformation to fused indolizines and pyrazolo [1, 5-a] pyridines except a few examples. This article describes novel preparative methods for some functionalized indolizines and pyrazolo [1, 5-a] pyridines and their transformation to new fused heterocycles using their functionality.抄録全体を表示PDF形式でダウンロード (1451K) -
ジアゾ化合物をビルディングブロックとする方法の展開伊藤 哲二, 平井 克幸, 富岡 秀雄2005 年 63 巻 3 号 p. 232-241
発行日: 2005/03/01
公開日: 2009/11/13
ジャーナル フリーMany attempts have been made in order to realize organic ferromagnetic materials. Triplet carbenes are regarded as one of the most effective spin sources since magnitude of the exchange coupling between the neighboring centers is large. However, those systems have not employed extensively due to two disadvantages that hinder their further extension to usable magnetic materials. First, a triplet carbene unit is highly unstable and lacks the stability for practical application under ambient conditions. In order to overcome these difficulties, we have made great efforts to stabilize and succeeded in preparing fairly stable ones surviving for days. The second disadvantage that arises is that diazo groups are also generally labile and, hence, are usually introduced at the last step of synthesis.We found, more or less by chance, that a diphenyldiazomethane for a persistent triplet carbene is also persistent at the stage of the diazo compound and, hence, can be further modified, with the diazo group intact, into a more complicated diazo compound. Thus, the diazo compound can be used as a building block to prepare a poly (diazo) compound, which can then generate high-spin polycarbene with considerable thermal stability. Here we would like to summarize how we have used this method to prepare a series of poly (diazo) compounds. Attempts to modify the diazo compound to a more congested derivative by taking advantage of the stability are also mentioned.抄録全体を表示PDF形式でダウンロード (1466K) -
小林 雄一, 古田 弘幸, 筧 昭一2005 年 63 巻 3 号 p. 242
発行日: 2005/03/01
公開日: 2009/11/13
ジャーナル フリーPDF形式でダウンロード (201K)
- |<
- <
- 1
- >
- >|