著者

林 雄二郎

出版者

The Society of Synthetic Organic Chemistry, Japan

雑誌

有機合成化学協会誌 (ISSN:00379980)

巻号頁・発行日

vol.63, no.5, pp.464-477, 2005-05-01 (Released:2009-11-13)

参考文献数

106

被引用文献数

73 77

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In the early 1970s, intramolecular aldol reaction catalyzed by proline was reported by Hajos et al., and its intermolecular version was discovered by List, Barbas, and Lerner in 2000. In the same year, MacMillan reported the asymmetric Diels-Alder reaction catalyzed by organocatalyst by lowering the LUMO energy of enones by the formation of iminium salt. After these two seminal papers, chiral small organic molecules have been widely employed in asymmetric synthesis because they have several advantages over the conventional transition metal based catalysts. Organic catalysts are inexpensive, readily available, and non-toxic. They are not sensitive to moisture and oxygen. The products are free from the contamination of metals. Because of these advantages, this field has been expanding so rapidly. Though there are so many asymmetric reactions catalyzed by organocatalysts, this article briefly summarizes the recent progress in the following reactions because of the limitation of space : Aldol reaction, Mannich reaction, Michael reaction, functionalization of α-position of carbonyl compounds, cycloaddition reactions such as Diels-Alder reaction, [3+2] cycloaddition reaction, and [4+3] cycloaddition reaction, allylation, Morita-Baylis-Hillman reaction, epoxidation, and phase-transfer reaction.

著者

山口 潤一郎 掛谷 秀昭 庄司 満 長田 裕之 林 雄二郎

出版者

天然有機化合物討論会

雑誌

天然有機化合物討論会講演要旨集

巻号頁・発行日

no.47, pp.25-30, 2005-09-15

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Lucilactaene (1), a cell-cycle inhibitor in p53-Transfected cancer, is a synthetically challenging molecule because of its rare hexahydro-3a-hydroxy-5-oxo-2H-furo [3,2-b]pyrrol-6-yl ring system and its substituted and conjugated E,E,E,E,E pentaene moiety, which is unstable to acid, base, and light. Lucilactaene (1), which readily undergoes racemization, has been synthesized for the first time in optically pure form via a biomimetic pathway. The conditions under which racemization occurs were elucidated during this total synthesis. The careful isolation of lucilactaene (1) from both the broth and the mycelia under neutral, nonracemizing conditions demonstrated that the isolable natural product is in fact itself racemic. This total synthesis, which enabled verification of the absolute configuration of lucilactaene (1), has several noteworthy features: All the reactions from NG-391 (2) are mild enough not to affect the labile E,E,E,E,E pentaene moiety; ether formation from 2 to 25 and 28 and the intramolecular Michael reaction from 26 to 27 or from 30 to 31 are both highly stereoselective; the reductive removal of the epoxide with Sml_2 without effecting demethoxylation, andthe deprotection of a hemiaminal under neutral, oxidative conditions via vinyl ether 33 by using a newly developed phenylselenylethyl protecting group, are also useful transformations.