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Progress in Chemo- and Regioselective Transformations of Symmetrical Cephalostatin Analogues

[ Vol. 15 , Issue. 2 ]

Author(s):

Mansour Nawasreh*   Pages 155 - 161 ( 7 )

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.

Affiliation:

Physics and Basic Sciences Department, Faculty of Eng. Techn./Al-Balqa Applied University, P.B. 15008, Marka 11134, Amman

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