[reaction: see text] The conversion of N-2,2-dichloropropionyl indole methyl ester into a tetracyclic cycloheptannelated indole model compound for the synthesis of dragmacidin E was accomplished in 10 steps. Key reactions include a Witkop cyclization to fashion a C-C bond at C(4) of the indole nucleus and a subsequent Dieckmann cyclization to deliver the desired cycloheptanoid ring.
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http://dx.doi.org/10.1021/ol0522081 | DOI Listing |
Org Lett
March 2020
School of Biotechnology and Health Sciences, Wuyi University, Jiangmen, Guangdong 529020, P. R. China.
An efficient and straightforward Lewis-acid-mediated stereoselective (4 + 3)-cyclization of indole-substituted alkylidene malonates and donor-acceptor cyclopropanes has been developed involving the Friedel-Crafts/Michael addition cyclization cascade. This reaction provides a mild and effective method for the construction of synthetically and structurally interesting functionalized cycloheptannelated indoles.
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October 2010
Chemistry Department, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
The conversion of a cycloheptannelated indole platform into the heptacyclic core structure of dragmacidin E proceeded over nine steps. Key sequences include a cyclocondensation to form an intermediate dihydropyrazinone ring and the conversion of a cyclic urea into the cyclic guanidine of the target.
View Article and Find Full Text PDFOrg Lett
November 2005
Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
[reaction: see text] The conversion of N-2,2-dichloropropionyl indole methyl ester into a tetracyclic cycloheptannelated indole model compound for the synthesis of dragmacidin E was accomplished in 10 steps. Key reactions include a Witkop cyclization to fashion a C-C bond at C(4) of the indole nucleus and a subsequent Dieckmann cyclization to deliver the desired cycloheptanoid ring.
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