Takeshi Nakanishi

Synthesis of derivatives of NK109, 7-OH Benzo[c]phenanthridine alkaloid, and evaluation of their cytotoxicities and reduction-resistant properties

The N5-C6 double bond of NK109 (an antitumor benzo[c]phenanthridine alkaloid) is easily reduced under biological environment. To suppress the inactivation caused by reduction, we synthesized 5-, 6-, and 8-substituted NK109. 5-Substituted derivatives (4a-c) were reduced more easily than NK109. 6-Substituted ones (10a-f) inhibited biological reduction, but showed weak cytotoxic activity. 8-O-Substituted ones (13a-h), especially 8-O-hydroxyethyl NK109 (13d), suppressed biological reduction and exhibited strong cytotoxic activity.

A convenient method for removal of the t-butyl group from nucleoside bis(t-butyl) phosphates under non-acidic conditions

Abstract A new method for selective removal of the t-butyl group from 3′ - bis(t-butyl) phosphate esters of 5′-0-(4,4′-dimethoxytrityl)deoxyribo-nucleosides was developed by use of Me 3 SiCl and Et 3 N. Several unexpected properties of the t-butyl group were described.

Regioselective O-Methylation of Hydroxyl Groups Via 1,3-Benzodithiol-2-Yl Ether Intermediates

Abstract A two-step regioselective O-methylation of hydroxyl groups via 1,3-benzodithiol ether intermediates has been developed. the O-alkylation of alcohols containing a phenolic hydroxyl group or pyridine skeleton was successfully performed.