天然有機化合物討論会講演要旨集
Online ISSN : 2433-1856
セッションID: 10
会議情報
10 コンパクチン(ML-236B)の不斉全合成
平間 正博上井 充子
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会議録・要旨集 フリー

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Compactin 1a (ML-236B) has become one of the prime targets aimed by a number of synthetic organic chemists since 1976, because of its high hypocholesterolemic activity and unique structural feature. A convergent and enantioselective synthesis of 1a has been achieved via asymmetric intramolecular Diels-Alder reaction of the acyclic (E,E,E)-trienone 4 leading to trans-octalone 3, which was a versatile intermediate to give all related compounds (1a, 1b, 2a and 2b) in the compactin family through the simple manipulation of the B ring functionality. 4 embodied the whole carbon-linkage necessary for 1a, and its intramolecular Diels-Alder reaction was considered to be a viable approach for the stereo-controlled construction of the trans-octalone. Our synthetic point based on the utilization of the allylic chiral center (C13) to control the approach of the dienophile from a single diastereotopic face of the diene. The four asymmetric centers (C8, C9, C14 and C17) with correct absolute configurations were expeditiously introduced by a choice of S configuration at C13-chirality. 4 was readily accessible by the Wadsworth-Emmons coupling of the optically active segments A (5) and B (6). Preparation of the acyclic 1,3,5-triol 6, masked form of the sensitive β-hydroxy-δ-lactone system, rested on a combination of a convenient and highly asymmetric reduction of β-keto acid 10d with baker's yeast and a subsequent regio- and stereoselective functionalization (i.e. 1,3-asymmetric induction) of the chiral homoallylic carbamate 13c using the novel carbamate-mediated iodocyclization. The synthesis of 5 in its optically active form was accomplished by the elaboration of the readily available 4S-γ-lactone 8.

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© 1982 天然有機化合物討論会電子化委員会
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