Oxymethylene bridge

Dinucleoside polyphosphates (NpnN′s; where N and N′ are nucleosides and n = 3–6 phosphate residues) are naturally occurring compounds that may act as signaling molecules. One of the most successful approaches to understand their biological functions has been through the use of NpnN′ analogs. Here, we present the results of studies using novel diadenosine polyphosphate analogs, with an oxymethylene group replacing one or two bridging oxygen(s) in the polyphosphate chain. These have been tested as potential substrates and/or inhibitors of the symmetrically acting Ap4A hydrolase (bis(5′‐nucleosyl)‐tetraphosphatase (symmetrical); EC ) from E. coli and of two asymmetrically acting Ap4A hydrolases (bis(5′‐nucleosyl)‐tetraphosphatase (asymmetrical); EC ) from humans and narrow‐leaved lupin. The six chemically synthesized analogs were: ApCH2OpOCH2pA (1), ApOCH2pCH2OpA (2), ApOpCH2OpOpA (3), ApCH2OpOpOCH2pA (4), ApOCH2pOpCH2OpA (5) and ApOpOCH2pCH2OpOpA (6). The eukaryotic asymmetrical Ap4A hydrolases degrade two compounds, 3 and 5, as anticipated in their design. Analog 3 was cleaved to AMP (pA) and β,γ‐methyleneoxy‐ATP (pOCH2pOpA), whereas hydrolysis of analog 5 gave two molecules of α,β‐oxymethylene ADP (pCH2OpA). The relative rates of hydrolysis of these analogs were estimated. Some of the novel nucleotides were moderately good inhibitors of the asymmetrical hydrolases, having Ki values within the range of the Km for Ap4A. By contrast, none of the six analogs were good substrates or inhibitors of the bacterial symmetrical Ap4A hydrolase.

The fundamental step, and usually the last, in the synthesis of β-blockers consists of adding a propanolamine side chain. This can be done following two paths which both involve alkylation of an appropriate phenoxide with epichlorohydrin (ECH). The first way is shown as the upper way in figure 5 . It consists of phenoxide reacting at the oxirane and resulting in an alkoxide, that displaces the adjacent chloride to form a new epoxide ring. The second way is shown as the lower route in figure 5 . It consists of displacement of the halogen directly with a S N 2 reaction to give the same glycidic ether. When following both pathways, the central chiral carbon preserves its configuration, which is an important part to consider when synthesizing enantiomerically defined drugs. The ring opening of the epoxide ring in glycidic ether is done with an appropriate amine, such as isopropyl amine or tert-butylamine, and leads to the aryloxypropanolamine compound that consist of a secondary amine. This amine is typically known as the structural requirement for the β-adrenergic blocking activity. [14]

Oxymethylene bridge

oxymethylene bridge

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