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Synthesis of (±)‐Kempa‐6,8‐dien‐3‐ol (=(2a RS ,3 SR ,4a SR ,7 RS ,7a SR ,10b SR ,10c SR )‐2,2a,3,4,4a,5,6,7,7a,8,10b,10c‐Dodecahydro‐2a,7,10,10c‐tetramethylnaphth[2,18‐ cde ]azulen‐3‐ol)
Author(s) -
Kato Tadahiro,
Tanaka Motoyuki,
Takagi Shinsuke,
Nakanishi Keita,
Hoshikawa Masahiro
Publication year - 2004
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.200490008
Subject(s) - chemistry , epimer , scheme (mathematics) , natural product , ring (chemistry) , stereochemistry , position (finance) , combinatorial chemistry , organic chemistry , mathematical analysis , mathematics , economics , finance
The synthesis of kempa‐6,8‐dien‐3 β ‐ol ( 4a ), as a synthetic leading model of the natural product 4b , was carried out starting from intermediate 12 , the synthetic route of which has been developed previously ( Scheme 1 ). The conversion of 12 to the model compound 4a involved the elaboration of three structure modifications by three processes, Tasks A, B , and C (see Scheme 2 ). Task A was achieved by epoxy‐ring opening of 41 with Me 3 SiCl ( Scheme 9 ), and Task B being performed by oxidation at the 13‐position, followed by hydrogenation, and then epimerization ( Schemes 4 and 5 ). The removal of the 2‐OH group from 12 ( Task C ) was achieved via 30b according to Scheme 6 , whereby 30b was formed exclusively from 30a / 31a 1 : 1 ( Scheme 7 ). In addition, some useful reactions from the synthetic viewpoint were developed during the course of the present experiments.