W. Dabkowski et al., 2,4-Dinitrophenol: a novel activating reagent in nucleotide synthesis via the phosphoramidite route. Design of new effective phosphitylating reagents, TETRAHEDR L, 41(39), 2000, pp. 7535-7539
2,4-Dinitrophenol (DNP) is a remarkably efficient activator in the reaction
of P(III) amides with nucleosides to give P(III) esters in excellent yield
. Typical examples of this novel procedure are presented heroin. Mechanisti
c features of the activation were elucidated by model studies of the reacti
on of bis(2-cyanoethyl)diisopropylphosphoroamidite with benzyl alcohol. The
importance of the initial protonation stage and formation of an intermedia
te P(III)-2,4-dinitrophenyl ester were clearly demonstrated by P-31 NMR spe
ctroscopy and independent synthesis. New phosphitylating reagents containin
g the 2,4-dinitrophenoxy group do not require any activation. (C) 2000 Else
vier Science Ltd. All rights reserved.