Amides table

By this procedure, the following amides (Table 16.2) may be prepared from the indicated starting materials in the approximate yields given. 

The last method for the preparation of 2-quinolones described in this chapter relies on a intramolecular Heck cyclization starting from heteroaryl-amides (Table 2) [57]. These are synthesized either from commercially available pyrrole- and thiophene-2-carboxylic acids (a, Table 2) or thiophene-and furan-3-carboxylic acids (b, Table 2) in three steps. The Heck cyclization is conventionally performed with W,Ar-dimethylacetamide (DMA) as solvent, KOAc as base and Pd(PPh3)4 as catalyst for 24 h at 120 °C resulting in the coupled products in 56-89% yields. As discussed in Sect. 3.4, transition metal-catalyzed reactions often benefit from microwave irradiation [58-61], and so is the case also for this intramolecular reaction. In fact, derivatives with an aryl iodide were successfully coupled by conventional methods, whereas the heteroarylbromides 18 and 19, shown in Table 2, could only be coupled in satisfying yields by using MAOS (Table 2). 

This procedure, which is based on the work of Ishii and co-workers, affords a mild and general method for converting a wide variety of esters to primary, secondary, and tertiary amides (Table 1). While the preparation of the tertiary amide, N,N-dimethylcyclohexanecarboxamide, described here is carried out in benzene, aluminum amides derived from ammonia and a variety of primary amines have been prepared by reaction with trimethylaluminum in dichloromethane and utilized for aminolysis in this solvent. Although 1 equivalent of the dimethylaluminum amides from amines was generally sufficient for high conversion within 5-48 hours, best results were obtained when 2 equivalents of the aluminum reagent from ammonia was used. Diethyl-aluminum amides can also effect aminolysis, but with considerably slower rates. 

On the basis of IR evidence it has been proposed84 that alkylamidates are the strongest known hydrogen-bonding carbonyl bases and that the order of hydrogen-bond basicity may be alkylamidates w FLMPA > vinylogous amides benzamidates > amides (Table 8). 

Azetidones (p-lactams) are generally obtained in high yield from (3-halopropion-amides (Table 5.18) and the low yield from the reaction of N-phenyl (3-chloropropi-onamide can be reconciled with the isolation of A-phenyl acrylamide in 58% yield [34]. The unwanted elimination reaction can be obviated by conducting the cyclization in a soliddiquid system under high dilution [35, 36]. Azetidones are also formed by a predominant intramolecular cyclization of intermolecular dimerization to yield piperazine-2,5-diones, or intramolecular alkylation to yield aziridones. Aone-pot formation of azetidones in 45-58% yield from the amine and P-bromocarboxylic acid chloride has also been reported [38]. 

Conversion of allyl phosphates into p,runsaturated amides (Table 8.10)... 

In a related process, Johnson and co-workers have developed an asymmetric metallophosphite-catalyzed intermolecular Stetter-hke reaction employing acyl silanes [81, 82], Acyl silanes are effective aldehyde surrogates which are capable of forming an acyl anion equivalent after a [l,2]-Brook rearrangement. The authors have taken advantage of this concept to induce the catalytic enantioselective synthesis of 1,4-dicarbonyls 118 in 89-97% ee and good chemical yields for a,p-unsaturated amides (Table 11). Enantioselectivities may be enhanced by recrystallization. 

Oxidative transformation of the amide function fails where a more easily oxidts-able group is present. Comparison of the o.xidation potentials for amides (Table 8.11) with those for aromatic rings (Tables 6.1 and 6.5) and for alkene bonds (Table 2.2) allows the reactivity of a multifunctional compound to be predicted. Whereas phenacylamides are oxidised with no interference from the aromatic ring,... 

Branched iV-chlorohydroxamic esters exhibit much lower carbonyl frequencies in their IR spectra. Series of Ai-(phenylethyloxy)amides (Table 2, entries 1-7) and Af-butoxy-amides (Table 2, entries 12-16) show a clear movement to lower carbonyl stretch frequencies with branching alpha to the carbonyl, in accord with greater inductive stabilization of the polar resonance form III of the carbonyl (Figure la). Neopentyl (entry 17) is a special case. While the group should contribute much more inductive stabilization than ethyl, its carbonyl stretch frequency is higher. Similar changes have been noted in the IR spectra of branched ketones and have been ascribed to a degree of steric hindrance to solvation and therefore destabilization of the polar resonance form Dl". ... 

The second dataset consists of 50 V-acetyl peptide amides (Table 2) these peptides have un-ionizable side chains and have previously been studied by Buchwald and Bodor (28). The three-dimensional structures of the di-peptides were built using the force field and partial charges of Kollman (29) as implemented in Sybyl 6.5.3. The initial random starting conformations were energy minimized in vacuo. For all calculations described herein, the dielectric of the medium was set to unity and the electrostatic cut-off distance was set to 16 A. For each molecule, the Sybyl Genetic Algorithm-based conformational search,... 

Reaction of the chiral lithium enolate of meso-2,6-dimethylcyclohexanone (6), generated by deprotonation with (R)-l-phenylethylamine and (/ )-camphor/(R)-l-phenylethylaniine derived chiral lithium amides (Table 1, entries 17 and 64) with 3-bromopropene, leads to homoallyl ketones of opposite absolute configuration in acceptable yield with poor to modest enantiomeric excess14, which can be determined directly by H-NMR spectroscopy in the presence of tris [3-(heptafluorohydroxymethylene)-D-camphorato]europium(III) [Eu(hfc)3]. 

Discrepancies in the enantioselectivity reported for the same lithium amide and reaction conditions may be due to different enantiomeric purity of the lithium amides (Table 6, entries 1 -3,4-6 and 7-9 and Table 7, entries 3-5) . Interestingly, for the elimination of the cw-epoxides enantioselectivity is higher in benzene than in tetrahydrofuran (Table 6, entries 1 and 3.12 and 13 and 14 and 15) whereas for that of the trans-epoxide the situation is reversed (Tabic 7, entries 2 and 6). The enantioselectivity of the elimination of the /rans-epoxide can be raised significantly through addition of DBU (Table 7, entries 6 and 7). 

This is an amide local anaesthetic and is widely used on account of its rapid onset, medium duration of effect, and low toxicity. It is less highly protein-bound than the longer-acting amides (Table 5.1) but it has a useful duration of effect and is the most versatile of all local anaesthetics. It is of intermediate potency and has less toxic potential than bupivacaine. It is available in aqueous solution as the hydrochloride salt in concentrations of 0.5-2.0% with and without adrenaline (epinephrine). Topical preparations are also available as gels or aerosols in 2-4% concentrations. 

Equilibrium diagrams, 22-26 construction of, 26-29 Equivalent weight of an acid, 1071 Ester-amides, table of, 425 Esterification, 379 -382, 1000, 1001 Esters, hydroxamic acid test for, 1062, 1063 ... 

Once it was established that pheromone biosynthesis was regulated by a peptide produced in the SEG, the next goal was to identify the peptide. In the purification of any biologically active factor, each purification step requires a sensitive bioassay to measure the active material. In the purification of PBAN, the bioassay consisted of head ligated females that were injected with bioactive fractions. After a 1-3 h period of incubation, the pheromone gland was excised and titers of pheromone determined by gas chromatography (GC). The first PBAN was purified and identified from H. zea (Raina el ah, 1989). Dissection of about 5000 brain-SEG complexes followed by several steps of HPLC purification resulted in a pure peptide that could be sequenced. It was found to be a 33 amino acid peptide with a C-terminal amide (Table 5.1). The peptide was synthesized and was shown to be active in the bioassay in a dose as low as 2 pmol (Raina et al., 1989). In the same year, a PBAN from B. mori was purified and sequenced (Kitamura et al.,... 

One of the earliest heterocyclic applications of the Ritter reaction was to the synthesis of dihydro-1,3-oxazines.9 It was found that the reaction of the dialcohol (1) with nitriles leads to the oxazines (2) rather than the expected bis-amides (Table I). The yields are only fair... 

Glycosyl imines from aliphatic aldehydes are sensitive to anomerization. However, the anomerization can be avoided by conducting the reactions at lower temperatures (-78 °C). Recrystallization of the crude products (methanol/water for aliphatic, heptane for aromatic compounds) gave the diastereomerically pure D-amino acid amides (Table 4.3). 

Analogously, Van Pelt et al. (2009) have realized a one-pot bienzymatic cascade combining the (5 )-selective oxynitrilase from M. esculenta and a purified nitrile hydratase from Nitriliruptor alkaliphilus for the synthesis of aliphatic S)-a-hydroxycarboxylic amides (Table 17.6) both enzymes were immobilized as CLEAs to enhance their stability (Van Pelt et al., 2009). 

Most examples of quinone dehydrogenations adjacoit to have been earned out on steroidal ketones and are essentially limited to readily enolizable species. Reactions on esters and amides (Table 8) are far less common and, because of their relatively low ease of enolization, require hanh conditions. Thus, unless stabilization of the intermediate carbonium ion is possible, - elevated temperatures and prolonged reaction times are required (Table 8), which increases the incidence of unwanted side reactions. Frequent by-products are those arising as a result of Diels-Alder reactions or Michael addition to the quinone." Allylic alcohols may be rapidly oxidized to aldehydes or ketones under these conditions and requite prior protection. 

The effect of the H bond on Vt is shown in the IR studies by Miyazawa of A -substituted amides (1420, 1421). The paper by Miyazawa, Shimanouchi, and Mizushima (1424) summarizes their assignments for a number of these amides. Table 3-XX lists a portion of their data pertaining to vt, the out-of-plane N—deformation [which they designate as amide V or 7t(N—H)]. 

Treatment of trithiane (73) with potassium amide (Table 17) gives spiro compound 74 in good yield Other dithioketal examples are shown. Cyclopropanone diselenoketals, i.e. 

Activation of aliphatic and aromatic carboxylic acids with sulfuric acid derivatives yields amides (Table 3). Sulfuryl chloride fluoride and primary amines or chlorosulfonyl isocyanate and secondary amines are used as reaction partners. 

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