Acyl group carbonyl

The systematic lUPAC name of ethyl acetoacetate is ethyl 3 oxobutanoate The presence of a ketone carbonyl group is indicated by the designation oxo along with the appro priate locant Thus there are four carbon atoms m the acyl group of ethyl 3 oxobutanoate C 3 being the carbonyl carbon of the ketone function... 

It should be noted that when 3-acylisoxazoles (116) are heated with a base such as sodium ethoxide, the acyl group is eliminated to give a carboxylate salt and a /3-ketonitrile (117). The reaction probably occurs via initial attack at the carbonyl group (46G206). 

In the diaziridine field many compounds are known bearing N-YL, A/-alkyl and A-acyl groups, but here no dramatic changes in reactivity are caused by A-substituents. N-Aryldiaziridines are underrepresented. The ring carbon is in the oxidation state of a carbonyl compound or, in the diaziridinones (5) and the diaziridinimines (6) that of carbonic acid. In single cases, diaziridine carbon bears chlorine or fluorine. 

A variant on this theme contains mixed acyl groups. In the absence of a specific reference it may be speculated that the synthesis starts with the diacetyl derivative (15). Controlled hydrolysis would probably give the monoacetate (16) since the ester para to the ketone should be activated by that carbonyl function. Acylation with anisoyl chloride followed by reduction would then afford nisobuterol (18). 

Acid halides are named by identifying first the acyl group and then the halide. The acyl group name is derived from the carboxylic acid name by replacing the -ic acid ending with -yl or the -carboxylic acid ending with -carbonyl, as described previously in Section 20.1 and shown in Table 20.1 on page 753. For example ... 

The way in which various substituents affect the polarization of a carbonyl group is similar to the way they affect the reactivity of an aromatic ring toward electrophilic substitution (Section 16.5). A chlorine substituent, for example, inductively withdraws electrons from an acyl group in the same way that it withdraws elections from and thus deactivates an aromatic ring. Similarly, amino, methoxvl, and methylthio substituents donate electrons to acyl groups by resonance in the same way that they donate electrons to and thus activate aromatic rings. 

Gas phase reactivity toward allyltrimethylsilane was used to compare the reactivity of several cyclic A-acyliminium ions and related iminium ions.203 Compounds with endocyclic acyl groups were found to be more reactive than compounds with exocyclic acyl substituents. Five-membered ring compounds are somewhat more reactive than six-membered ones. The higher reactivity of the endocyclic acyl derivatives is believed to be due to geometric constraints that maximize the polar effect of the carbonyl group. 

Mononuclear acyl Co carbonyl complexes ROC(0)Co(CO)4 result from reaction of Co2(CO)8 with RO-.77 These also form via the carbonylation of the alkyl precursor. The ROC(0)Co(CO)4 species undergo a range of reactions, including CO ligand substitution (by phosphines, for example), decarbonylation to the alkyl species, isomerization, and reactions of the coordinated acyl group involving either nucleophilic attack at the C or electrophilic attack at the O atom. 

Insertion takes place between a Jt-bonded fragment and a a-bonded fragment in mutual cis-positions, as was described above. The de-insertion reaction can only proceed if there is a vacant site cis to the acyl group. The experiment outlined in Figure 2.12 proves this point. A manganese acetyl complex which is labelled with 13C at the acyl carbonyl group was synthesised and heated to give de-insertion of CO. The result was that the only product formed contained the methyl substituent in a position cis to the labelled 13C. 

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