Acyl compounds structures

On heating to 140°C in the absence of a solvent, the Al-acyl compounds 18 rearrange quantitatively to the isomeric structures 17. " The rate of reaction is increased by bulky ring substituents, being immeasurably slow when R = R = R = Me it also depends on the nature of R Crossing experiments have shown the migration to be intermolecular. ... 

Pantothenic acid is a component of coenzyme A, which functions in the transfer of acyl groups (Figure 28.17). Coenzyme A contains a thiol group that carries acyl compounds as activated thiol esters. Examples of such structures are succinyl CoA, fatty acyl CoA, and acetyl CoA. Pantothenic acid is also a component of fatty acid synthase (see p. 182). Eggs, liver, and yeast are the most important sources of pan tothenic acid, although the vitamin is widely distributed. Pantothenic acid deficiency is not well characterized in humans, and no RDA has been established. 

For the sake of brevity, salient aspects of key structure-activity relationships in one homologous series of twelve mono- and bis-acyl homologated spermine analogues (Fig. 12.8) will be first discussed (Miller et al., 2005). We addressed two questions in this study (i) what is the optimal hydrophobic chain length for effective anti-endotoxic activity, (ii) are symmetrical bis-acyl spermines more effective than mono-acyl compounds We found that a carbon number of 14-16 is optimal in mono-acyl spermines (Fig. 12.9) which are, in general, as potent as... 

Glyceraldehyde-3-phosphate dehydrogenase has an essential cysteine residue in its active site. The enzyme forms a transient acyl compound with its substrate, glyceraldehyde 3-phosphate, (a) What is the general chemical name of the compound (b) Draw its likely structure. 

The carbonyl carbon of an amide is sp hybridized and has trigonal planar geometry. A second resonance structure can be drawn that delocalizes the nonbonded electron pair on the N atom. Amides are more resonance stabilized than other acyl compounds, so the resonance structure having the C=N makes a significant contribution to the hybrid. 

Curved Brpnsted plots or other structure-reactivity correlations are often taken as evidence for changes in transition-state structure with changing properties of the reactant that might be described by the Marcus equation (24) or other equations. However, it is important to evaluate other possible explanations for such curvature, including solvation effects that could decrease the reactivity of basic nucleophiles without any change in the structure of the transition state for nucleophilic attack. For example, solvation effects could provide a relatively simple explanation for the curvature of structure-reactivity correlations for reactions of basic oxygen anion nucleophiles with acyl compounds and carbon acids. 

The reaction of diaz (26) with Fe2(CO)g yields [(diaz)Fe2(CO)g] which contains no N—N bond and two non-equivalent iron atoms. Spectral studies and an X-ray crystallographic determination have also been reported, [(diaz H2)Fe2(CO)g] [diaz H2 = (27)] has also been isolated and spectroscopic studies of this compound indicate that it possesses a similar structure to [(diaz)Fc2(CO)g], but with somewhat greater distortions at one of the octahedral iron atoms. Reactions of phthalazine with iron carbonyls have also been studied and are outlined in Scheme 2. The p-acyl compounds [Fc2(CO)g-(p-COR)2] react with donor ligands (L) to form [Fe2(CO)5L(p-COR)2] (R = Me or Ph L = NH3, Et2NH, PhNHNHj, py, or CsH,oNH) and with thiols and selenols to form [Fe(CO)3(p-X)]2 (X = SEt or SePh) and the aldehydes PhCHO and MeCHO. Reaction of [Fe2(CO)g(p-COPh)2] with three molar equivalents of PR3 gives (28), Fe(CO)3(PR3)2 (R = Ph or Pr ), and carbon monoxide. The structure of (29) has been determined. ... 

Tenuazonic acid (741), a phytotoxin produced by Alternaria spp., is structurally related to the tetramic acid family of compounds, and has been found to exhibit antibiotic activity (511). Since 1964, there have been several publications on the total synthesis of 741 (512-515), including the report by Poncet and his group in 1990 (516) (Scheme 11.10). A general method to synthesize the tetramic acids is an intramolecular Dieckmann cyclization of (V-acyl amino esters. Beginning with methyl L-isoleucinate 780, the A/-acyl compound 782 was obtained through a nucleophilic reaction (512), which then cyclized to tenuazonic acid 741 under basic conditions and neutralization by acidic work-up. The synthetic product showed a diastereomeric excess of 89%, with the major epimer presenting the same configuration as its precursor (517). 

Given here are the NMR spectra and carbonyl IR absorption peaks of five acyl compounds. Propose a structure for each. 

In an interesting reaction, treatment of [AlMe(OC6H2Bu2-2,6-Me )2] with acetyl chloride was found to yield the complex [AlMe(OC6H2Bu -2,6-Me )(OC6H2Bu -2-Me-4-CMeO-6)] in which one of the aryloxide ligands was acylated. The structural parameters for this latter compound were discussed in terms of the above two resonance forms. The structural parameters for both a- and -hydroxy carbonyl ligands bound to aluminium have been discussed. ... 

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