Basic region synthesis

Promoters are DNA regions capable of specific initiation of transcription (start of RNA synthesis) and consist of three basic regions (See Figure 4.2). The part determining the exact nucleotide for transcriptional initiation is called the core promoter and is the stretch of DNA sequence where the RNA polymerase and its cofactors assemble on the promoter. 

Control of the pH is also of importance for the Mannich-based bispidine synthesis. Formation of an aldol product competes with the Mannich condensation in the basic pH region. It is for this reason that, in some cases, the reaction is sensitive to the order in which the reactants are added to the reaction mixture. It is possible to add the aldehyde and amine components one after another to a solution of the CH-acidic compound, but sometimes the aldol reaction can be disfavored by changing the order. This allows the imminium ion to be formed in advance. The precursors of 45 and 46 have been prepared by this method. In some cases, it has been useful to use a protonated amine component as the acetate salt (e.g., 49 or precursors for 44, 47, and 48), as the chloride salt (e.g., 11) or to carry out the reaction in acetic acid. Aromatic amines (e.g., aniline) give rise to para-substituted aromatic amines if the solution is not approximately neutral. In a very elegant procedure, a condensate of formaldehyde and aniline, which is the trimeric methyleneaniline, was prepared separately, and treated in the Mannich reaction with dimethyl acetonedicarboxylate and formaldehyde to yield the 3,7-diphenylbispidone... 

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