16625-37-9Relevant articles and documents
Enantioselective total synthesis of (-)- Stenine
Chen, Jingbo,Chen, Jingchao,Xie, Yan,Zhang, Hongbin
, p. 1024 - 1027 (2012/02/16)
In control: (-)-Stenine has been synthesized in 14 steps from commercially available compounds with an overall yield of 5.9 % by using a method that is based on double Michael addition. In the key step, the stereogenic centers that are required for (-)-stenine are generated in a highly stereocontrolled, asymmetric, one-pot cyclization to give a densely substituted cyclohexane core. Copyright
Studies on the synthesis of (±)-stenine: A combined intramolecular [4 + 2]-cycloaddition/rearrangement cascade
Padwa, Albert,Ginn, John D.
, p. 5197 - 5206 (2007/10/03)
Several cyclic 2-(methylthio)-5-amidofurans containing tethered unsaturation were prepared via the reaction of dimethyl(methylthio)sulfonium tetrafluoroborate (DMSTF) with β-alkoxy-γ-dithiane lactams. Thermolysis of these furans resulted in an intramolecular Diels-Alder reaction (IMDAF). The resulting oxa-bridge cycloadducts underwent a subsequent 1,2-methylthio shift to form tricyclic lactams in high yield. Furan 9, annealed to an azepine ring, underwent the IMDAF reaction at or below room temperature. Conformational effects imposed by the placement of a carbonyl group within the tether, combined with a rotational bias about the C(2)-N bond, enhances the rate of the IMDAF reaction of the seven-ring system so that it occurs readily at 25 °C. The feasibility of using the cascade sequence in the context of a total synthesis of the Stemona alkaloid (±)-stenine was explored. The eventual synthesis of (±)-stenine was carried out by an intramolecular Diels-Alder reaction of a 2-amido-5-methylthio-substituted furan containing a trans-pent-3-enoic acid methyl ester side chain in order to create the desired azepinoindole skeleton. This was followed by a series of reductions to set the syn-anti stereochemical relationship at the incipient ring fusion sites present in stenine. All six stereocenters at the azepinoindole core were derived in high stereoselectivity from the functionality present in the rearranged cycloadduct 10. Compound 10 was converted to stenine in 11 additional steps via a sequence that features a Crabtree's-catalyst directed hydrogenation, iodolactonization, and a Keck allylation.
Total synthesis of (+/-)-stenine using the IMDAF cycloaddition of a 2-methylthio-5-amido-substituted furan.
Ginn, John D,Padwa, Albert
, p. 1515 - 1517 (2007/10/03)
[reaction: see text]. The intramolecular [4 + 2]-cycloaddition of a 2-methylthio-5-amidofuran was used to create the azepinoindole skeleton present in the Stemona alkaloid stenine. The rearranged cycloadduct was converted to stenine (1) in 11 additional steps via a sequence that features a Crabtree catalyst directed hydrogenation (9-->10), iodolactonization (2-->11), and a Keck allylation (11-->12).
