64657-11-0Relevant articles and documents
Regioselective acetylation of 7-deacetylforskolin with 11C-acetyl chloride
Sasaki,Furukata,Ishii,Iimori,Ikegami,Nozaki,Senda
, p. 337 - 347 (1996)
Reaction conditions were studied to control the acetylating position on 7-deacetylforskolin using [11C]acetyl chloride. In a preliminary study using non-labeled acetyl chloride, pyridine, lutidine, triethylamine, N,N-diisopropylethylamine, dimethylaminopyridine (DMAP) and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) were tested as the base in the acetylation. Pyridine was effective in selective acetylation to yield forskolin in any solvent, and DBU was effective for 1-acetyl-7-deacetylforskolin. Among toluene, dichloromethane and dichloroethane, toluene was the most suitable as the solvent for the selective acetylation of the 7-OH group to give forskolin with any base. In the selectivity of acetylation with [11C]acetyl chloride, more [11C]forskolin was obtained than [11C]1-acetyl-7-deacetylforskolin (70:30) in the presence of pyridine in toluene. [11C]1-acetyl-7-deacetylforskolin was preferentially synthesized with DBU in dichloromethane, and the ratio of [11C]1-acetyl-7-deacetylforskolin to [11C]forskolin was 98:2. For the yield of the [11C]acetylated product, DBU in dichloromethane was also suitable to obtain [11C]1-acetyl-7-deacetylforskolin. However, that of pyridine in toluene did not confer any advantages upon the yield of [11C]forskolin compared with DMAP in toluene.
Expedient synthetic transformation of ptychantins into Forskolin
Hagiwara, Hisahiro,Tsukagoshi, Masashi,Hoshi, Takashi,Suzuki, Toshio,Hashimoto, Toshihiro,Asakawa, Yoshinori
, p. 929 - 931 (2008)
Forskolin has been synthesized in 11 steps with a 17% overall yield from ptychantins A and B, which have been isolated from the liverwort Ptychanthus striatus in good yield. The 1α-hydroxy group was furnished by stereoselective reduction of the corresponding carbonyl group by sodium cyanoborohydride. The 9α-hydroxy group was introduced stereoselectively by epoxidation of Δ9,11-enol ether. Georg Thieme Verlag Stuttgart.
A Concise Synthesis of Forskolin
Hylse, Ond?ej,Maier, Luká?,Ku?era, Roman,Pere?ko, Tomá?,Svobodová, Aneta,Kubala, Luká?,Paruch, Kamil,?venda, Jakub
, p. 12586 - 12589 (2017/09/12)
A 24-step synthesis of (±)-forskolin is presented, which delivered hundred milligram quantities of this complex diterpene in one pass. Transformations key to our approach include: a) a strategic allylic transposition, b) stepwise assembly of a sterically encumbered isoxazole ring, and c) citric acid-modified Upjohn dihydroxylation of a resilient tetrasubstituted olefin. The developed route has exciting potential for the preparation of new forskolin analogues inaccessible by semisynthesis.
Total synthesis of forskolin - Part II
Delpech, Bernard,Calvo, Daniel,Lett, Robert
, p. 1019 - 1022 (2007/10/03)
The further elaboration of the key-intermediate 5 into forskolin 1 has been achieved via two different routes. Key features of this new total synthesis are: 1) the stereospecific formation of the 6β, 7β, 8α-triol via the BF3-Et2O assisted opening of the epoxy carbamate 8; 2) use of the 8α, 11-di-t-butylsilylene ketal for the specific protection of the 6β, 7β-diol, from the tetrol 10(A); two new sequences for the formation of the dihydro-γ-pyrone ring in high overall yield from 23; 4) the stereoselective divinyl cuprate conjugate α-addition on the dihydro-γ-pyrone 16 or 28, in the presence of BF3-Et2o, with the stereochemistry required for forskolin synthesis.
