Carboxylic derivs., reactions

Carboxylic derivs., reaction, 230-244 acid hydrolysis, 240, base hydrolysis, 238 electronic effects in, 237 Grignard reagents, 238... 

Pentenamer Ionomers. Unsaturated polypentenamer elastomers have been derivatized by post-synthesis reactions (72—74). Phosphonate, thioglycolate, sulfonate, and carboxylate derivatives have been prepared and converted into ionomers. 

Correlations with o in carboxylic acid derivative reactions have been most successful for variations in the acyl portion, R in RCOX. Variation in the alkyl portion of esters, R in RCOOR, has not led to many good correlations, although use of relative rates of alkaline and acidic reactions, as in the defining relation, can generate linear correlations. The failure to achieve satisfactory correlations with cr for such substrates may be a consequence of the different steric effects of substituents in the acyl and alkyl locations. It has been shown that solvolysis rates of some acetates are related to the pA", of the leaving group, that is, of the parent alcohol. The pK of alcohols has been correlated with but this relationship... 

This is another reaction that involves carbanions derived from esters, e.g. (Ill), but this time adding to the carbonyl carbon atom of another ester molecule. The reason for considering it here rather than under carboxylic derivatives (p. 237) is that it can, in its initiation, be regarded as something of an analogue, for esters, of the aldol condensation on aldehydes (cf. p. 224), e.g. with ethyl ethanoate (acetate, 112) ... 

ADDITION/ELIMIN ATION REACTIONS OF CARBOXYLIC DERIVATIVES... 

In an extension of previous work on conjugated enamine carbonyl derivatives, reaction of the pyrazolone 91 with IV.lV-disubstituted hydrazines on heating in an alcohol solvent afforded the hexahydropyrazolo[4,3-Michael-type addition of the alcohol to a pre-formed pyrazolo-diazepine, was excluded <06T8126>. 

A number of BODIPY derivatives that contain reactive groups able to couple with amine-containing molecules are commonly available. The derivatives either contain a carboxy-late group, which can be reacted with an amine in the presence of a carbodiimide to create an amide bond, or an NHS ester derivative of the carboxylate, which can react directly with amines to form amide linkages. The three discussed in this section are representative of this amine-reactive BODIPY family. The two NHS ester derivatives react under alkaline conditions with primary amines in molecular targets to form stable, highly fluorescent derivatives. The carboxylate derivative can be coupled to an amine using the EDC/sulfo-NHS reaction discussed in Chapter 3, Section 1.2. 

Table 5 1,2,4-Oxadiazoles available from the reaction of carboxylic derivatives with amidoximes (see Equation 33)...

Solid-phase synthesis of dihydropteridinones has been achieved from 4,6-dichloro-5-nitropyrimidine <00TL8177>. A series of ethyl 7-aminopteridine-6-carboxylate derivatives has been prepared in one step from the reaction of vicinal diamines as 13-dialky 1-5,6-diamino-2-thiouracils with diethyl ( )-2,3-dicyanobutenedioate <99JHC1317>. The relative binding affinities to human dihydrofolate reductase of new 2,4-diaminopteridine derivatives... 

The mechanisms of reactions of anionic nucleophiles with carboxyl derivatives and phosphate esters are similar in that negative charge tends to be localized on oxygen in the transition states, as shown for deacylation in Scheme 5 (Bunton, 1977). The transition state here should be stabilized by... 

This carboxylation reaction is of importance mainly for the manufacture from 2-naphthol of P-oxynaphthoic acid (BON) acid, the parent acid of sodium 3-hydroxy-2-naphthoate (4-35). The carboxylation is achieved by heating the sodium salt of 2-naphthol under pressure in an atmosphere of carbon dioxide (Scheme 4.25). Under these conditions an equilibrium mixture of the naphthol and its carboxylated derivative is established, the mixture containing about 30% of the carboxylic acid. The desired product is extracted from the reaction mixture and the unchanged 2-naphthol is recycled. 

Methyl oxetane-2-carboxylate derivatives (e.g., 284), obtained by ring contraction of aldonolactones, have been employed for the synthesis (279) of the nucleoside / -noroxetanocin [9-(/ -D-eryt/iro-oxetanosyl)adenine, 304] and its a-anomer via an a-chloride obtained by a modified Hunsdiecker reaction. Displacement of chloride by adenine and debenzylation gave 304. The threo isomer of304, /J-epinoroxetanocin (305), was likewise synthesized from D-lyxono-1,4-lactone. The oxetane nucleosides display potent antiviral activity against the human immunodeficiency virus (HIV). 

Intramolecular addition of trialkylboranes to imines and related compounds have been reported and the main results are part of review articles [94, 95]. Addition of ethyl radicals generated from Et3B to aldimines affords the desired addition product in fair to good yield but low diaster control (Scheme 40, Eq. 40a) [96]. Similar reactions with aldoxime ethers [97], aldehyde hydrazones [97], and N-sulfonylaldimines [98] are reported. Radical addition to ketimines has been recently reported (Eq. 40b) [99]. Addition of triethylborane to 2H-azirine-3-carboxylate derivatives is reported [100]. Very recently, Somfai has extended this reaction to the addition of different alkyl radicals generated from trialkylboranes to a chiral ester of 2ff-azirine-3-carboxylate under Lewis acid activation with CuCl (Eq. 40c) [101]. 

The reaction of cephalosporanic acid (1598) and cyclopenteno(6)pyri-dine in a 3 1 mixture of water and acetone in the presence of potassium iodide and ascorbic acid at 66-68°C for 4 hr gave the pyridiniumceph-3-ene-4-carboxylate derivative (1599) in 14% yield (84GEP3316796). 

If the reactants are oppositely charged, the collision complex in (5.18) takes the form of an outer-sphere complex with discernable stability. For the outer sphere redox reaction between Co(NH3)jL"+ and Fe(CN)g, L being a series of pyridine or carboxylate derivatives, saturation kinetics are observed, with the pseudo first-order rate constant (/ obs)> Fe(II) in excess, being given by... 

STEREOSELECTIVITY IN CARBONYL ADDITION REACTIONS, p. 234. ADDmON/EUMINATION REACTIONS OF CARBOXYLIC DERIVATIVES,... 

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