Propiolic acid derivatives

Scheme 2.47. Addition of zinc-copper compounds to propiolic acid derivatives.

Mononitro compounds could be selectively obtained in the nitration of phenyl-propiolic acid derivatives with HNO3-HSO3F at low temperature501 [Eq. (5.191)]. Addition of fluorosulfuric acid to the triple bond, however, may also take place with substituted derivatives. 

Addition of in situ generated trichlorostannane to propiolic acid derivatives furnishes the corresponding j9-trichlorostannylacrylic acid derivatives (Scheme 33) [144]. The procedure provides an access to trialkyltin free alkenyltin reagents. 

Table 5. Solvent effects on regioselectivity in the additions of pyrollidine and n-propylamine to 2-furyl- and phenyl-propiolic acid derivatives, X—R—C=CCOY (equation 53) >...

Functionalized thiazole-fused thiopyrans can be regio- and diastereose-lectively prepared through [4 + 2] cyclocondensation reactions, in which 5-arylideneisorhodanines are used as heterodienes and crotonic, cinnamic, and propiolic acid derivatives serve as dienophiles (Scheme 80) (14T720). 

Examples of [4+2] cycloadditions in the solid state remain relatively rare, owing to an inherent difficulty in arranging two different molecules in a suitable geometry for reaction. Desiraju and Radha Kishan reported the first solid-state [4+2] cycloaddition, which involved a propiolic acid derivative (Figure 23a and b). Kochi and... 

The intermolecular reaction of phenols with propiolic esters occurs in the presence of a Pd(OAc)2 catalyst to afford coumarin derivatives directly.48,48a An exclusive formation of 5,6,7-trimethoxy-4-phenylcoumarin is observed in the Pd(OAc)2-catalyzed reaction of 3,4,5-trimethoxyphenol with ethyl phenylpropiolate in TFA (Equation (46)). Coumarin derivatives are obtained in high yields in the cases of electron-rich phenols, such as 3,4-methylenedioxyphenol, 3-methoxyphenol, 2-naphthol, and 3,5-dimethylphenol. A similar direct route to coumarin derivatives is accomplished by the reaction of phenols with propiolic acids (Equation (47)).49 A similar reaction proceeds in formic acid at room temperature for the synthesis of coumarins.50,50a Interestingly, Pd(0), rather than Pd(n), is involved in this reaction. 

Propiolic acids. The ylide derived from 1 converts aldehydes into propiolic esters or the acids in 50-70% yield. 

Acetylenic esters react well with copper-zinc compounds. Propiolic esters are especially reactive [83], but other acetylenecarboxylic acid derivatives such as dimethyl acetylenedicarboxylate or propiolamide 118 undergo highly stereoselective cis addition (Scheme 2.47) [46]. 

The cyclopropyl-allyl rearrangement has been shown to proceed with nucleophilic assistance,87i232<233 and the intermediate allyl cation can be trapped by nucleophiles leading to synthetically useful derivatives. An example is the formation of an unsaturated acetal and the propiolic acid ortho ester (equations 92 and 93).232... 

Vallee, Y. The reaction of propiolate acetylides with nitrones. Synthesis of y-amino-a,/ -ethy-lenic acid derivatives. Tetrahedron Lett. 1997,... 

The action of potassium ferricyanide upon copper acetylene derivatives is interesting. Diacotylouo-dicarboxylic acid is obtained from tho copper derivative of propiolic acid by treatment with forricyanido 6 yc - c.cooh c c.cooii... 

Diphenyl-diacetylene is the parent hydi ocarhon of indigo blue, and the dye itself can be prepared by means of tliis reaction, starting with o-nitro-phenyl-propiolic acid. By loss of carbon dioxide the acid becomes o-nitro-phenyl-acetylene, the copper derivative of which passes to di-ortho-nitrophenyl-diacety-lene ... 

Diselenetane derivative 39 reacts with elemental selenium in the presence of a catalytic amount of triphenyl-phosphine or triphenylphosphine selenide to give 1,2,4-triselenolane 65 in 37% yield (Scheme 9) <2001TL3881>. The reaction with propiolic acid under reflux conditions in toluene affords selenodioxenone 66 (25%) and trace amounts of compound 67 <2004BCJ1933>. 

Several disubstituted acetylenes containing other heteroatoms have been found to polymerize Derivatives of propiolic acid (PhC = CC02H, H02CC=CC02H) can be polymerized by MoCls— cocatalyst40). The polymerization of l-(ferrocenyl-l-propyne) is effected by WCl —Ph Sn 49). The MW s of these polymers, however, are not very high. 

Polycarbobetaines derived from aromatic or heteroaromatic systems are listed in Scheme 3. The vinylimidazolium betaines 13 and 14 were prepared by alkylation of 1-vinyhmidazole with the corresponding bromocarboxylic acid, and aqueous solution polymerization using an azo initiator [29]. Polymers 13b, 15, 16, and 17b were made by the addition of acryUc or propiolic acid to poly(4-vinylpyridine) and poly(N-vinylimidazole). Kinetic measurements revealed a mechanism consisting of two reactions first, addition of two molecules of acid to the polymer second, the formation of an equilibrium between the adduct and the betaine structure [30,31]. 

By the oxidation of propargyl alcohol, propinol, CH=C—CH2OH (p. 167), an acid is obtained having the constitution CH=C—COOH and known as propiolic acid or propinoic acid and also as acetylene carboxylic acid. This is the simplest acid of the ethine series and the only one we shall mention. Derivatives of it are of importance in the benzene series in Part li as will be shown later. 

This acid is the simplest aromatic acid with the carboxyl in the side chain. Its name, phenyl acetic acid, indicates the relation to the aliphatic acids as a phenyl derivative. The commonly used names for the side-chain carboxy acids are derived similarly, e.g. phenyl propiolic acid. It will be seen at once that phenyl acetic acid and the toluic acids are isomeric, the first being the result of the partial oxidation of ethyl benzene, the latter the result of the partial oxidation of the di-methyl benzenes or xylenes which are isomeric with ethyl benzene. In both cases the relationship to the hydrocarbon is that only one carbon group of the side chain is oxidized to carboxyl. 

The side-chain carboxy acids which we have studied are phenyl acetic, phenyl propionic or hydrocinnamic, phenyl acrylic or cinnamic and phenyl propiolic. Phenol derivatives of all of these are known. Hydroxy phenyl acetic acid is not important. 

Special interest was focused on the photochemistry and redox properties of mononuclear ruthenium complexes.20 Examples show the nucleophilic attack of one of the N atoms of 1,8-naphthyridine on the coordinated CO in [Ru(bipy)2(napy)(CO)]2+ upon le reduction of the napy moiety (Scheme 2). Such a type of metallacyclization enables the reduction of the CO group, derived from the electrochemical reduction of C02 catalyzed by [Ru(bipy)(napy)2(CO)2](PF6)2, to produce acetone in the presence of Me4NBF4.21,22 An unusual result is the simultaneous formation of a carbene ligand and the addition of the methoxo group to the naphthyridine ring upon reaction of [Ru(bipy)2(napy)]2+ with propiolic acid in methanol (Scheme 2).23... 

Danishefsky has exploited his widely utilized silyloxydiene chemistry to complete a formal total synthesis of 90 (Scheme 1.20). By employing the appropriate oxidation levels for both the diene and dienophile, a resorcinyl ester possessing the required differentiation of the phenolic groups was obtained without further oxidative manipulation. To this end, the dianion of propiolic acid was alkylated with l-bromo-7-octene to give acid 98 in 68% yield. Further alkylation with methyl iodide then gave the ester 99. A Diels-Alder reaction with diene 100, a derivative of methyl acetoacetate, and alkyne 99 then furnished an initial phenolic intermediate which was protected as the benzyl ether to afford... 

Amongst the most commonly used reagents are DMAD [2280, 2419, 2422, 2523, 2830], bis(methyUhio)methyIenemalonic acid derivatives [3491, 3571], propiolic acid nitrile [2280], 3-methoxyacrylic ester or nitrile [3704], 2- or... 

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