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Synthesis reduction with ethylene glycol

Carbon-11 labeled BPA, 4, was synthesized from the corresponding aldehyde, 4-boronophenylacetaldehyde, 9. This boronated aldehyde was prepared from commercially available 4-bromophenylacetic acid, 10, in five synthetic steps (Scheme 1). The synthesis was initiated by the borane reduction of acid 10 to the 2-(4-boronophenyl)ethyl alcohol, 11. Alcohol 11 was then carefully oxidized to aldehyde 12. In the next step, 4-bromophenylacetaldehyde, 12, was refluxed with ethylene glycol in the presence of a catalytic amount of/>-toluenesulfonic acid to obtain the corresponding acetal 13.The boronic acid moiety was introduced at the para position of the phenyl ring 1 the reaction with butyllithium followed by triisopropyl borate" to obtain the 4-bronophenylacetaldehyde ethylene acetal, 14. In the final step of the synthesis, acetal 14 was treated with concentrated hydrochloric acid in methanol as solvent to obtain the desired precursor, 4-boronophenylacetaldehyde, 9, for the synthesis of carbon-11 labeled BPA, 4, Scheme 2. [Pg.122]

Recent investigations have shed light on peculiarities of the NOS action mechanism the role of the H4B cofactor and CaM, and cooperativity in kinetic and thermodynamic properties of different components of the nitric oxide synthesis system. Stop flow experiments with eNOS (Abu-Soud et al., 2000) showed that calmodulin binding caused an increase in NADH-dependent flavin reduction from 0.13 to 86 s 1 at 10 °C. Under such conditions, in the presence of Arg, heme is reduced very slowly (0.005 s 1). Heme complex formation requires a relatively high concentration ofNO (>50 nM) and inhibits the entire process NADH oxidation and citrulline synthesis decreases 3-fold and Km increases 3-fold. NOS reactions were monitored at subzero temperatures in the presence of 50% ethylene glycol as an anti-freeze solvent (Bee et al., 1998). [Pg.114]


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See also in sourсe #XX -- [ Pg.339 ]




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Ethylene syntheses

Glycolate synthesis

Glycols, reduction

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