Carboxylic acids alkenyl

The reaction of alkenyl mercurials with alkenes forms 7r-allylpalladium intermediates by the rearrangement of Pd via the elimination of H—Pd—Cl and its reverse readdition. Further transformations such as trapping with nucleophiles or elimination form conjugated dienes[379]. The 7r-allylpalladium intermediate 418 formed from 3-butenoic acid reacts intramolecularly with carboxylic acid to yield the 7-vinyl-7-laCtone 4I9[380], The /i,7-titisaturated amide 421 is obtained by the reaction of 4-vinyl-2-azetidinone (420) with an organomercur-ial. Similarly homoallylic alcohols are obtained from vinylic oxetanes[381]. 

Formation of carboxylic acids ami their derivatives. Aryl and alkenyl halides undergo Pd-catalyzed carbonylation under mild conditions, offering useful synthetic methods for carbonyl compounds. The facile CO insertion into aryl- or alkenylpalladium complexes, followed by the nucleophilic attack of alcohol or water affords esters or carboxylic acids. Aromatic and a,/ -unsaturated carboxylic acids or esters are prepared by the carbonylation of aryl and alkenyl halides in water or alcohols[30l-305]. 

The addition of various alkyllithium reagents to ( )-2-(l-alkenyl)-4,5-dihydrooxazoles in THF at —78 °C followed by acid hydrolysis gave nonracemic chiral / ,/>-disubstituted carboxylic acids in high enantiomeric purity (>91% ee). 

Also via Alkenyl Acids Section 322 (Carboxylic Acid -Alkene)... 

A wide range of A-acylbenzotriazoles 915 have been prepared under mild conditions in reactions of carboxylic acids with thionyl chloride in the presence of fourfold excess of benzotriazole, including R = alkyl, a-haloalkyl, a-alkoxyalkyl, alkenyl, alkinyl, aryl, and heteroaryl <2003S2795, 2004RQM275>. They represent convenient acylating agents for variety of nucleophiles. Synthetic applications of such compounds have been reviewed <2005SL1656>. 

Alkene loss via McLafferty rearrangement at the alkoxy group of aliphatic and aromatic carboxylic acid esters competes with yet another reaction path, where two hydrogens instead of one as in the normal McLafferty product are transferred to the charge site. This second pathway leading to alkenyl loss has early been noticed [94] and became known as McLafferty rearrangement with double hydrogen transfer (r2H) ... 

The transformation of lithio derivatives of dibenzothiophene into alkyl, alkenyl, hydroxyalkyl, formyl, acetyl, carboxylic acid, alkyl and arylsilyl, boronic acid, aryl and carbinol derivatives of dibenzothiophene is dealt with in the appropriate sections. In addition, the four mono-tritio derivatives of dibenzothiophene have been prepared from the corresponding lithio derivatives via hydrolysis with tritiated water (Section III, 0,2). ... 

As indicated in Section ni.B, deprotonation of a carbamate affords a dipole-stabilized a-amino-organolithium that can be transmetalated with copper salts to form cuprates, thereby expanding the versatility of the organolithium. Suitable electrophiles include enones, alkenyl, alkynyl, allenyl and dienyl carboxylic acid derivatives, nitriles and sulfoxides. Dieter and coworkers have shown that the same process can be accomplished via transmetalation of a stannane (Scheme 36). The procedure is particularly... 

The use by Langlois of an amidoalcohol (79,80) is an unusual strategy for the construction of a-amino acids. More commonly, the required amine and carboxylic acid functionalities are carried into the cycloaddition in the dipolarophile, as a homochiral alkenyl a-amino acid derivative. Importantly, this introduces a second... 

Dr L.Deffet, Bruxelles private communication, March 10,1954 Alkenyl Aromatics of the general formula Ar. CH, CHa. C CH2, were prepd by reacting aruEliatic nyuiocarbons (at moderate temp and press) with 1,3 diolefins in the presence of a catalyst(such as boron trihalide satd with an organic carboxylic acid). The purified alkenyl aromatics can be nitrated to yield expl derivs... 

Hydroperoxide formation is characteristic of alkenes possessing tertiary allylic hydrogen. Allylic rearrangement resulting in the formation of isomeric products is common. Secondary products (alcohols, carbonyl compounds, carboxylic acids) may arise from the decomposition of alkenyl hydroperoxide at higher temperature. 

Alkenyl-2-azetidinone systems could be converted to bicyclic (3-lactam carboxylic esters and hence carboxylic acids (Fig. 5) via tandem Ireland-Claisen rearrangement and subsequent alkene metathesis [250],... 

The major improvement compared to the Rh(I) catalysts was the ability of the Cu(I)/RB (OR )2 system to also carboxylate alkenyl-boronic esters in very good yield, under similar conditions. Interestingly, the system functioned better under ligandless conditions, producing the corresponding unsaturated carboxylic acids in good yields. 

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