- Total syntheses of the diterpenoids (-)-kolavenol and ( -)-agelasine B
-
The trans-clerodane diterpenoids (-)-kolavenol (2) and (-)-agelasine B (1) have been prepared from the enantiomerically pure decalone 3. The key steps of the syntheses involve the stereo selective alkylation of the nitrile 4 (to give 5), the efficient coupling of the iodides 10 and 11 to produce the clerodane skeleton 12, and the electrochemical reduction of 16 to provide (-)-1.
- Piers, Edward,Roberge, Jacques Y.
-
-
Read Online
- Decarboxylative alkenylation
-
Olefin chemistry, through pericyclic reactions, polymerizations, oxidations, or reductions, has an essential role in the manipulation of organic matter. Despite its importance, olefin synthesis still relies largely on chemistry introduced more than three decades ago, with metathesis being the most recent addition. Here we describe a simple method of accessing olefins with any substitution pattern or geometry from one of the most ubiquitous and variegated building blocks of chemistry: alkyl carboxylic acids. The activating principles used in amide-bond synthesis can therefore be used, with nickel- or iron-based catalysis, to extract carbon dioxide from a carboxylic acid and economically replace it with an organozinc-derived olefin on a molar scale. We prepare more than 60 olefins across a range of substrate classes, and the ability to simplify retrosynthetic analysis is exemplified with the preparation of 16 different natural products across 10 different families.
- Edwards, Jacob T.,Merchant, Rohan R.,McClymont, Kyle S.,Knouse, Kyle W.,Qin, Tian,Malins, Lara R.,Vokits, Benjamin,Shaw, Scott A.,Bao, Deng-Hui,Wei, Fu-Liang,Zhou, Ting,Eastgate, Martin D.,Baran, Phil S.
-
p. 213 - 218
(2017/05/19)
-
- TERPENOID COMPOUNDS FROM PARENTUCELLIA LATIFOLIA
-
Together with phytol, sitosterol acetate, α-tocopherylquinone annd sitosterol, the neutral part of Parentucellia latifolia afforded seven esters of diterpene alcohols: 7,13E-labdadien-15-ol acetate; ent-3,13E-clerodadien-15-ol acetat; di-malonate; 7,13E-labdadien-15-yl and ent-3,13E-clerodadien-15-yl malonic acid diester; di- malonate; 7,13E-labdadien-15-yl-methyl malonic acid diester; ent-3-13E-clerodadien-15-yl-methyl malonic acid diester.Three nor diterpenes: 14,15-dinor-7-labden-13-one; 14,15-dinor-ent-3-cleroden-13-one; 14,15-dinor-ent-2,4(18)clerodadien-13-one; and seven diterpene alcohols, five of them isolated as acetyl derivatives: 7,13E-labdadien-15-ol; ent-3,13E-clerodadien-15-ol; diacetate of 8,(17),13E-labdadien-7α,15-diol; 15-acetoxy-13E-labden-8β-ol; 15-acetoxy-13E-labden-8-ol and 15-acetoxy-ent-3,13E-clerodadien-2-one.
- Urones, J. G.,Marcos, I. S.,Cubillo, L.,Garrido, N. Martin,Basabe, P.
-
p. 2223 - 2228
(2007/10/02)
-
- ONE THE CONSTITUENTS OF LINARIA JAPONICA MIQ. IV. CHEMICAL CORRELATION OF CIS-CLERODANE DITERPENES WITH TRANS-CLERODANE DITERPENES
-
The chemical correlation between 5α-methyl-trans-clerodane diterpenes and 5β-methyl-cis-clerodane diterpenes was investigated.Attempts to correlate a trans-clerodane with a cis-clerodane by virtue of i) photoisomerization of a
- Kitagawa, Isao,Kamigauchi, Toshiyuki,Yonetani, Kazuto,Yoshihara, Minoru
-
p. 2403 - 2413
(2007/10/02)
-