Carbonyl group derivatives

A variety of carbonyl group derivatives of cyclopropenones have been reported. The reaction of diphenylcyclopropenone with phosphorus pentasulfide gives diphenylcyclo-propenethione (equation 62). The thione has also been prepared using thioacetic acid... 

Maruoka, K., Yamamoto, H. Functionai group transformations via carbonyl group derivatives, in Comp. Org. Synth, (eds. Trost, B. 

Because of its symmetrical structure, a molecule of succinate derived from a 14C-labeled acetyl-CoA is converted into two forms of oxaloacetate, one with a labeled methylene group and one with a labeled carbonyl group. 14C-Iabeled CO, is not released until the third turn of the cycle when one-half of the original labeled carbon is lost (the carbonyl group derived from acetyl-CoA). The labeled carbon is further scrambled when succinyl-CoA is converted to succinate during the third and fourth turns of the cycle. 

Another carbonyl group derivative which forms an imidazole ring with a diamine is 5,iS-dimethyl-Af-tosyliminodithiocarbonimidate (76.10), which is useful in the synthesis of 8-aminopurines. In an attempt to prepare a l,S-benzo-diazepine, the chloroaldehyde (76.11) was stirred or warmed with o-phenylene-diamine but the main product was the benzimidazole. 

There are few examples of ene reactions using carbonyl group derivatives, such as thioke-tones107 and imines, and only in the case of nitrogen derivatives has stereochemical control been investigated. 

The latter substance was unusual in that it was colored and had a very high m.p. ( > 300°), and it seems possible that it was not a simple carbonyl group derivative. 

Formation of Carbonyl Group Derivatives, Both phenyl- and diphenyl--cyclopropenones have been reported to form 2,4-dinitrophenyl-... 

The electrophilicity of a carbonyl group derives from resonance effects as well as inductive effects ... 

More restricted specificity is found in other enzymes, the activities of which require that the substrate molecule contains a distinct structural feature in addition to the reactive functional group. Examples are the proteinases tr3fpsin and chymotrypsin which cleave only ester or peptide bonds with the carbonyl group derived from lysyl or arginyl (trypsin) or t3rosyl, phenylalanyl or tryptophanyl residues (ch3miotr3fpsin). Many enzymes activate only one single substrate or preferentially catalyze the conversion of one substrate while other substrates are converted into products with a lower reaction rate (cf. ex-... 

More recently, Fei and coworkers have employed the Ugi/deprotection/activation/ cyclization strategy for their synthesis of DKPs 191 using CIC IW3 (Scheme 7.66) [74] Anhydrous HCl, which forms in situ, helps deprotect the Boc group and activates the amide carbonyl group derived from IW3. 

Hammen equation A correlation between the structure and reactivity in the side chain derivatives of aromatic compounds. Its derivation follows from many comparisons between rate constants for various reactions and the equilibrium constants for other reactions, or other functions of molecules which can be measured (e g. the i.r. carbonyl group stretching frequency). For example the dissociation constants of a series of para substituted (O2N —, MeO —, Cl —, etc.) benzoic acids correlate with the rate constant k for the alkaline hydrolysis of para substituted benzyl chlorides. If log Kq is plotted against log k, the data fall on a straight line. Similar results are obtained for meta substituted derivatives but not for orthosubstituted derivatives. 

Hydrazine and its alkylated derivatives are used as rocket fuels in organic chemistry, substituted phenylhydrazines are important in the characterisation of sugars and other compounds, for example aldehydes and ketones containing the carbonyl group C=0. 

The isopropyl group could be derived from a carbonyl group and a Grignard reagent in two ways ... 

Terminal alkyne anions are popular reagents for the acyl anion synthons (RCHjCO"). If this nucleophile is added to aldehydes or ketones, the triple bond remains. This can be con verted to an alkynemercury(II) complex with mercuric salts and is hydrated with water or acids to form ketones (M.M.T. Khan, 1974). The more substituted carbon atom of the al-kynes is converted preferentially into a carbonyl group. Highly substituted a-hydroxyketones are available by this method (J.A. Katzenellenbogen, 1973). Acetylene itself can react with two molecules of an aldehyde or a ketone (V. jager, 1977). Hydration then leads to 1,4-dihydroxy-2-butanones. The 1,4-diols tend to condense to tetrahydrofuran derivatives in the presence of acids. 

The reaction of amines with the 4-phenylazo derivative (228) results in their rearrangement into triazolines. Depending on the basicity of the amines and the size of the alkoxy group, three different triazolines (229. 230, and 231) are obtained (Scheme 117) (454. 459, 472). In all cases, the first step involves nucleophilic addition of the amine to the carbonyl group followed by ring opening and further ring closure. 

Although the present chapter includes the usual collection of topics designed to acquaint us with a particular class of compounds its central theme is a fundamental reaction type nucleophilic addition to carbonyl groups The principles of nucleophilic addition to aide hydes and ketones developed here will be seen to have broad applicability m later chap ters when transformations of various derivatives of carboxylic acids are discussed... 

The chemistry of the carbonyl group is probably the single most important aspect of organic chemical reactivity Classes of compounds that contain the carbonyl group include many derived from carboxylic acids (acyl chlorides acid anhydrides esters and amides) as well as the two related classes discussed m this chapter aldehydes and ketones... 

What structural features are responsible for the reactivity order of carboxylic acid derivatives Like the other carbonyl containing compounds that we ve studied they all have a planar arrangement of bonds to the carbonyl group Thus all are about the same in offering relatively unhindered access to the approach of a nucleophile They differ m the degree to which the atom attached to the carbonyl group can stabilize the carbonyl group by electron donation... 

Thioesters Like chlorine sulfur is a third row element with limited ability to donate a pair of 3p electrons into the carbonyl tt system With an electronegativ ity that IS much less than Cl or O however its destabilizing effect on the carbonyl group IS slight and thioesters he m the middle of the group of carboxylic acid derivatives m respect to reactivity... 

Most methods for their preparation convert one class of carboxylic acid derivative to another and the order of carbonyl group stabilization given m Figure 20 1 bears directly on the means by which these transformations may be achieved A reaction that converts one carboxylic acid derivative to another that lies below it m the figure is pracfical a reacfion fhaf converts if fo one fhaf lies above if is nol This is anofher way of saying fhaf one carboxylic acid derivative can be converted to another if the reaction leads to a more stabilized carbonyl group Numerous examples of reacfions of fhis fype will be pre senfed m fhe secfions fhaf follow... 

The first stage of the mechanism is exactly the same as for nucleophilic addition to the carbonyl group of an aldehyde or ketone Many of the same nucleophiles that add to aldehydes and ketones—water (Section 17 6) alcohols (Section 17 8) amines (Sections 17 10-17 11)—add to the carbonyl groups of carboxylic acid derivatives... 

Conversions of acid anhydrides to other carboxylic acid derivatives are illustrated m Table 20 2 Because a more highly stabilized carbonyl group must result m order for nucleophilic acyl substitution to be effective acid anhydrides are readily converted to carboxylic acids esters and amides but not to acyl chlorides... 

The carbonyl group of an amide is stabilized to a greater extent than that of an acyl chlo ride acid anhydride or ester amides are formed rapidly and m high yield from each of these carboxylic acid derivatives... 

Infrared IR spectroscopy is quite useful in identifying carboxylic acid derivatives The, carbonyl stretching vibration is very strong and its position is sensitive to the nature of IKT the carbonyl group In general electron donation from the substituent decreases the double bond character of the bond between carbon and oxygen and decreases the stretch mg frequency Two distinct absorptions are observed for the symmetric and antisym metric stretching vibrations of the anhydride function... 

Section 20 2 The structure and reactivity of carboxylic acid derivatives depend on how well the atom bonded to the carbonyl group donates electrons to it... 

Aldoses incorporate two functional groups C=0 and OH which are capable of react mg with each other We saw m Section 17 8 that nucleophilic addition of an alcohol function to a carbonyl group gives a hemiacetal When the hydroxyl and carbonyl groups are part of the same molecule a cyclic hemiacetal results as illustrated m Figure 25 3 Cyclic hemiacetal formation is most common when the ring that results is five or SIX membered Five membered cyclic hemiacetals of carbohydrates are called furanose forms SIX membered ones are called pyranose forms The nng carbon that is derived... 

Tesla (Section 13 3) SI unit for magnetic field strength Tetrahedral intermediate (Section 19 14 and Chapter 20) The key intermediate in nucleophilic acyl substitution Formed by nucleophilic addition to the carbonyl group of a car boxyhc acid derivative... 

Aldol Addition and Related Reactions. Procedures that involve the formation and subsequent reaction of anions derived from active methylene compounds constitute a very important and synthetically useful class of organic reactions. Perhaps the most common are those reactions in which the anion, usually called an enolate, is formed by removal of a proton from the carbon atom alpha to the carbonyl group. Addition of this enolate to another carbonyl of an aldehyde or ketone, followed by protonation, constitutes aldol addition, for example... 

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