Progress in Chemo- and Regioselective Transformations of Symmetrical Cephalostatin Analogues

Author(s): Mansour Nawasreh*.

Journal Name: Letters in Organic Chemistry

Volume 15 , Issue 2 , 2018

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Abstract:

As a part of our continuous efforts in synthesizing potent anti-cancer natural product cephalostatin 1 and its analogues using a symmetrical bits-steroidal diketone, progress in the chemoselective distinction of the two parts is reported. The first strategy involves the highly chemoselective reductive opening of the spiroketal moiety (ring-F) of nonsymmetrical diol precursor. Thus, the protected 12β,12´α-diol underwent a chemoselective ketal opening using the catechol-borane complex yielding mono-opened spiroketal product with high chemoselctivity. Additionally, 11α-methoxy diketone derivative led to the corresponding mono-opened spiroketal product when treated with 4-methylcatecholborane, a modified reducing complex. The same derivative underwent a chemo- and regioselective hydration of the D-ring double bond using diaminobenzonitrile-borane complex. These key developments pave the way to prepare cephalostatin 1 and analogues.

Keywords: Cephalostatins, chemoselectivity, spiroketal ring-opening, selective D-ring hydration, spiroketal reconstruction, transformation.

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Article Details

VOLUME: 15
ISSUE: 2
Year: 2018
Page: [155 - 161]
Pages: 7
DOI: 10.2174/1570178614666170907113121
Price: $65

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