Esters alicyclic

Two-step 1,4 cycloaddition of enamines, such as was observed with methyl vinyl ketone, is not possible with acrylate or maleate esters. This is due to the fact that, following the initial simple substitution, no side-chain carbanion is available for nueleophilic attack on the a carbon of the iminium ion. Likewise two-step 1,3 eycloaddition, such as that found when alicyclic enamines were treated with acrolein, is impossible with acrylate or maleate esters because transfer of the amine moiety from the original enamine to the side chain to form a new enamine just prior to the final cyclization step is not possible. That is, the reaction between a seeondary amine and an ester does not produce an enamine. 

Finally, it is important to mention that there are other related publications in which porphyrin macrocycles are not directly used as dipolarophiles but are transformed into new derivatives that can react with carbonyl ylides via ACE (alkene cyclobutene epoxide) reactions. This idea arose in 1997, when Russell and co-workers found that fused ester-activated cyclobutene epoxides 86 can be ring-opened to give carbonyl ylides 87, and that these can be trapped stereospecifically by ring-strained alicyclic dipolarophiles, such as 2,5-norbomadiene, to form hetero-bridged norbomanes 88 in good yields, through ACE transformations (Scheme 31) <97CC1023>. 

At a high temperature (>200°C), the reaction with alicyclic ketones is a very attractive application of DMC as a methoxycarbonylating agent. In particular, cyclopentanone and cyclohexanone, whose reactions with DMC (or (3 = diethylaminoethyl chokide hydrochloride (DEC)] and a base (K2CO3) yield adipic and pimelic dimethyl (or diethyl) esters, respectively (Scheme 4.18). ... 

Rule of thumb The stability of molecular ions roughly decreases in the following order aromatic compounds > conjugated alkenes > alkenes > alicyclic compounds > carbonyl compounds > linear alkanes > ethers > esters > amines > carboxylic acids > alcohols > branched alkanes. [81]... 

In more complex enaminocarbonyl systems, the dominant form of the cation depends to some extent upon the nature of the system, e.g., whether or not part of the chain [244] is involved in a large structure, such as an alicyclic or aromatic ring, and whether or not the carbonyl group takes part in another competing conjugation, as in the ester group. Ultraviolet and infrared spectroscopy are... 

We report here that polyethylene adipate (PEA) and polycaprolactone (PCL) were degraded by Penicillium spp., and aliphatic and alicyclic polyesters,ester type polyurethanes, copolyesters composed of aliphatic and aromatic polyester (CPE) and copolyamide-esters (CPAE) were hydrolyzed by several lipases and an esterase. Concerning these water-insoluble condensation polymers, we noted that the melting points (Tm) had a effect on biodegradability. 

The fungus assimilated various polyesters. In general, assimilation of aliphatic polyesters by the fungus was better the greater the number of carbon atoms between the ester bonds. Polyesters with side chains were generally less assimilated than without side chains. The fungus also assimilated unsaturated aliphatic polyesters, but hardly assimilated alicyclic and aromatic polyesters. 

The parent 4-oxo-2-thioxopyrimidines 305 (cis, n = 1, 2 trans, n = 2 R = H), 306 cis or trans), 307 and 308 diendo and diexo) were prepared analogously to pyrimidinediones by reacting the corresponding amino ester hydrochlorides with potassium thiocyanate (89MRC959), or from alicyclic ethyl 2-isothiocyanato-l-carboxylates, obtained by the reaction of amino esters and thiophosgene with ammonia (96UP2). 

Cyclization of the isothiocyanates obtained from alicyclic )8-amino esters with thiophosgene and 2-chloroethyl or 3-chloropropylamine gave the thia-zolopyrimidinones 464-467 (96UP2). 

The enthalpy of fomation of two such species has been measured, namely the cyclopropane and cycloheptane derivatives. The difference between the values for these two species, both as solids, is 238.1 kJmol . Is this difference plausible Consider the difference between the enthalpies of formation of the parent cycloalkanes as solids, 194 kJ mol . The ca 44 kJ mol discrepancy between these two differences seems rather large. However, there are idiosyncracies associated with the enthalpies of formation of compounds with three-membered rings and almost nothing is known at all about the thermochemistry of compounds with seven-membered rings. Rather, we merely note that a seemingly well-defined synthesis of cycloheptyl methyl ketone was shown later to result in a mixture of methyl methylcyclohexyl ketones, and superelectrophilic carbonylation of cycloheptane resulted in the same products as methylcyclohexane, namely esters of 1-methylcyclohexanecarboxylic acid. The difference between the enthalpies of formation of the unsubstituted alicyclic hydrocarbons cycloheptane and methylcyclohexane as solids is 33 kJmol . This alternative structural assignment hereby corrects for most of the above 44 kJ mol discrepancy in the enthalpies of formation of the two oximes. More thermochemical measurements are needed, of oximes and cycloheptanes alike. 

Reiter et al. studied the condensations of 3-methylthio-AT and 3-morpholino-AT, respectively, with ethoxymethylene-cyanoacetate (and -malonitrile) in acetic acid or DMF (or mixtures) and isolated only the corresponding 7-amino-TP (87JHC1149). Analogous reactions of aliphatic (90M173) and alicyclic 3-ketocarbonic esters (87JHC1503 890PP163 91JHC721) always resulted in 7-oxo-TPs as the major products and 5-oxo-TPs as by-products. 

Some alicyclic alcohols are important as synthetic sandalwood fragrances. A few alicyclic aldehydes are valuable perfume materials and are obtained by Diels Alder reactions using terpenes and acrolein. Esters derived from hydrogenated aromatic compounds, such as /cr/-butylcyclohexyl and decahydro-/3-naphthyl acetates, are also used in large amounts as fragrance materials. 

The principal constituents of rosin (qv) are abietic and related acids. Tall oil (qv) is a mixture of unsaturated fatty and alicydic acids of the abietic family. Refined tall oil may be high in rosin acids or unsaturated acids, depending on the refining process. Ethoxylates of rosin acids, eg, dehydro abietic acid, are similar to fatty acid ethoxylates in surfactant properties and manufacture, except for their stability to hydrolysis. No noticeable decomposition is observed when a rosin ester of this type is boiled for 15 min in 10% sulfuric acid or 25% sodium hydroxide (90). Steric hindrance of the carboxylate group associated with the alicyclic moiety has been suggested as the cause of this unexpectedly great hydrolytic stability. 

The reaction is very general. The aldehyde or ketone may be aliphatic, alicyclic, or aromatic (including diaryl ketones) it may contain double or triple bonds it may contain various functional groups, such as OH, OR, NR2, aromatic nitro or halo, acetal, or even ester groups.643 Double or triple bonds conjugated with the carbonyl also do not interfere, the attack being at the 0=0 carbon. 

Aromatic esters may be used to aroylate the dianions derived from 1,3-diketones by reaction with potassium amide (60JOC538). Not only are acetyl and benzoyl acetones suitable for reaction, but alicyclic diketones and 2-hydroxyacetophenone are also acceptable. Cycliz-ation of the triketones occurs in cold sulfuric acid, presumably via the enolic form and the hemiacetal (Scheme 132). 

First, peak heights are measured at five points in the NMR spectra (Figure 2). All NMR spectra of fulvic acids described in this study were determined as the sodium salt in D20 at pH 8 (21). Peak heights were used rather than peak areas to minimize overlapping spectral contributions from various proton structures. From structural-model considerations, peak 1 appears to be a combination of methylene and methine protons in aliphatic alicyclic rings and branched methyl groups located beta to carbonyl groups of a carboxylic acid, ester, or ketone. The structural model rules out meth-... 

Various groups have reported that additions of a-hetero substituted ester enolates to a,3-enones are temperature dependent, l40 c but, in general, the 1,2 to 1,4-equilibration of a-seleno and a-thio substituted ester adducts occurs at lower temperature than the a-oxo substituted ester adducts. In contrast to the simple ester enolates, the a-hetero substituted ester enolates are extremely useful for functionalization of alicyclic a,(3-enones with the tandem conjugate addition-electrophile trapping protocol, as shown... 

Carbonyl compounds will be taken in this chapter to mean any organic compound that contains at least one carbon-oxygen double bond where we limit the substitution to only saturated aliphatic, saturated alicyclic and aryl hydrocarbyl groups. Carbonyl compounds with a variety of unsaturated substituents have earlier been discussed within the context of enones4. Non-hydrocarbyl substituents, X , may be directly attached to the carbonyl and elsewhere in the molecule. The first type of species, RCOX, is alternatively identified as acyl derivatives such as carboxylic acids and their esters, halides and amides and have already been discussed in a recent Patai thermochemistry... 

The hydroxyl group of a primary, secondary, or tertiary acyclic or alicyclic alcohol may be protected by conversion into (a) an ether, (b) a silyl ether, or (c) an ester. The most important method for the protection of a 1,2- or 1,3-diol is conversion into (d) a cyclic acetal. 

The Arndt-Eistert reaction is a comparatively simple method for converting an acid into its next higher homologue, or to a derivative of the homologous acid, such as an amide or an ester. The reaction is applicable to aliphatic, aromatic, alicyclic and heterocyclic acids, and the yield is generally good. 

The carboxyl group of aliphatic and alicyclic carboxylic acids may be protected by conversion into a variety of organic esters silylation affords a valuable alternative. 

Esterification with alicyclic alcohols proceeds best when the alcohol is saturated with hydrogen chloride and treated with an excess of the carboxylic acid (the Fischer-Speier method) a very impure ester results if sulphuric acid is used as the catalyst. 

Solvolysis rates of isopropenyl chloroformate, CH2=C(Me)0C(0)Cl, were shown to be very similar to those for 4-nitrobenzoyl chloride in mechanism and reactivity.29 Stepwise mechanisms were observed in the aminolysis of aryl chloroformates by a series of substituted quinuclidines - which were more reactive than isobasic secondary alicyclic amines.30 The pH-independent hydrolysis of 4-nitrophenyl chloroformate in MeCN-H20 mixtures proceeded via a cyclic transition state containing the ester and two water molecules.15 Solvolyses of 2-furancarbonyl chloride in most... 

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