Ethanolamine nucleophilic addition

One simple way for arriving at a photoinduced Markovnikov-type amination of olefins is illustrated in Scheme 3.15, for the case of o-alkenylphenols (e.g., 24). Here, an ammonium salt of the o-alkenylphenolate anion (25) is prepared and irradiated this causes proton transfer within the ion pair (from the amine to the olefin), and the resulting zwitterion undergoes nucleophilic addition of the amine at the benzylic cation center. The addition is selective for N- rather than O-nucleophiles, as shown in the case of ethanolamine [34]. 

On the one hand, alternative basic deprotection cocktails were developed using various combinations of hydrazine, ethanolamine, and alcohol [146] or incorporating the use of more nucleophilic alkylamines [7,16]. The latter method favors 40% aqueous methylamine in place of or in addition to 30% ammonium hydroxide, which cleaves the acyl protecting groups present on the nucleobases in a few minutes at 65°C or in over 1 h at room temperature. 

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