“…Classical organic chemical reactions allow the transformation of carbonyl derivatives into amines; the carboxylic acids can be converted to amines through well-known reactions, such as the Hofmann , (eq 5) and Curtius , (eq 6) rearrangements. …”
The oxidation of N-alkylamides by O(2), catalyzed by N-hydroxyphthalimide (NHPI) and Co(II) salt, leads under mild conditions to carbonyl derivatives (aldehydes, ketones, carboxylic acids, imides) whose distribution depends on the nature of the alkyl group and on the reaction conditions. Primary N-benzylamides lead to imides and aromatic aldehydes at room temperature without any appreciable amount of carboxylic acids, while under the same conditions nonbenzylic derivatives give carboxylic acids and imides with no trace of aldehydes, even at very low conversion. These results are explained through hydrogen abstraction by the phthalimide-N-oxyl (PINO) radical, whose reactivity with benzyl derivatives is governed by polar effects, so that benzylamides are much more reactive than the corresponding aldehydes. The enthalpic effect is, however, dominant with nonbenzylic amides, making the corresponding aldehydes much more reactive than the starting amides. The importance of the bond dissociation energy (BDE) of the O-H bond in NHPI is emphasized.
“…Classical organic chemical reactions allow the transformation of carbonyl derivatives into amines; the carboxylic acids can be converted to amines through well-known reactions, such as the Hofmann , (eq 5) and Curtius , (eq 6) rearrangements. …”
The oxidation of N-alkylamides by O(2), catalyzed by N-hydroxyphthalimide (NHPI) and Co(II) salt, leads under mild conditions to carbonyl derivatives (aldehydes, ketones, carboxylic acids, imides) whose distribution depends on the nature of the alkyl group and on the reaction conditions. Primary N-benzylamides lead to imides and aromatic aldehydes at room temperature without any appreciable amount of carboxylic acids, while under the same conditions nonbenzylic derivatives give carboxylic acids and imides with no trace of aldehydes, even at very low conversion. These results are explained through hydrogen abstraction by the phthalimide-N-oxyl (PINO) radical, whose reactivity with benzyl derivatives is governed by polar effects, so that benzylamides are much more reactive than the corresponding aldehydes. The enthalpic effect is, however, dominant with nonbenzylic amides, making the corresponding aldehydes much more reactive than the starting amides. The importance of the bond dissociation energy (BDE) of the O-H bond in NHPI is emphasized.
“…Aromatic amines are very important compounds, being the structural units of some medicinally important molecules and many other industrially relevant materials . The amino function can be introduced into the benzene ring by a wide variety of methods, i.e., by the reduction of a nitro moiety, by the replacement of a halogen atom, by rearrangement reactions, etc. 7a,b Different anilines have also been obtained by the amination of arenes with azodicarboxylates, followed by the reduction of the primary-formed hydrazino intermediates, 7c,d by the Buchwald−Hartwig cross-coupling reaction, 7e-g by the microwave-assisted replacement of a halogen atom with the amino moiety,7h etc.…”
The Diels-Alder reactions of a variety of 2H-pyran-2-ones 1 with alkynes 2 yielding highly substituted aniline and o-phenylenediamine derivatives 4 with novel (and in some cases known but very rare and useful) structural patterns are presented. The effect of substituents of both reactants on the reaction rates was investigated. The reactions were carried out under thermal conditions, as well as at high pressures.
“…(c) The electronic and steric similarities between halogens and the azido group (56) (40,53). Based on bond strengths, known reactivities of aryl azides, and the lack of precedent for biological hydrogenolytic cleavage of the Car-N bond, the possibility that the N3-IAA might be metabolized to IAA itself is negligible (1,5,8,56). The 2-and 7-azido isomers were not chosen for use as fluorescent photoaffmity labeling agents because of both the low auxin activity of the corresponding chloro compounds (25,48) and the likelihood of tetrazole or tetrazine formation, respectively, with the ring nitrogen (7).…”
Three auxin analogs, 4-, 5-, and 6-azido-3-indoleacetic acid (4N3-IAA, 5-N3-IAA, and 6-NA-IAA) have been synthesized for use as fluorescent photoaffinity labeling agents. The pKa values of these compounds (4-N3-IAA, 4.67; 5-Ns-IAA, 4.65; 6-N3-IAA, 4.66; all ± 0.04) are experimentally indisfinguishable from the pK. of 3-indoleacetic acid (IAA, 4.69 ± 0.04). The auxin activity of these IAA derivatives has been determined in several systems. In soybean, pea, and corn straight growth assays, all three analogs induce growth comparable to that caused by IAA. In the tobacco pith assay, anl three analogs elicit a maximum increase in fresh weight at least 40 to 50% of that caused by IAA. Optimal growth is attained in the tobacco pith assay at slightly higher concentrations of 4Ns-IAA and 6-N3-IAA (30 micromolar) than required for IAA (10 micromolar); however, maximal growth is achieved at a slightly lower concentration of 5-N3-IAA (3 micromolar). The NA-IAAs, like IAA, are transported basipetally through tobacco pith tissue.Auxins, the longest known class of plant hormones, modulate a wide variety of cell functions, the most significant being cell elongation (21,31,39,42,54,55). Despite extensive investigation, the mechanism of auxin action is still unknown, although it is now generally recognized that the response to auxins occurs in two phases (58,60,61). Within the past decade, reversible binding between auxins and several cell components has been demonstrated, establishing tentative locations of auxin receptors within the cell (17, 19, 23, 27, 43, 45, 50-52, 59, 61-66) (41).The decline in the rate of appearance of reports on auxin binding in the past 2 years compared to the rate during the 6 years immediately following the initial demonstration of auxin binding (23) and recent attempts to predict the properties of the auxin receptor from empirical structure-activity correlations (29,33,49) signal the need for a fresh approach to the problem of isolating an auxin receptor.To this end, we have synthesized three auxin analogs, 4-, 5-, and 6-azido-3-indoleacetic acid (4-N3-IAA, 5-N3-IAA, and 6-N3-IAA)7 for use as fluorescent photoaffinity labeling agents. The technique of photoaffinity labeling, which has been used to study animal hormones and to characterize the active sites of enzymes, has been thoroughly reviewed (6, 14-16, 30, 32
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