Acetylene derivatives esters

Apart from lactic and hydroxyacetic acids, other a- and P-hydroxy acids have been small-volume specialty products produced in a variety of methods for specialized uses. y-Butyrolactone [96 8-0] which is the monomeric inner ester of y-hydroxybutyric acid [591-81-17, is a large-volume chemical derived from 1,4-butanediol (see Acetylene-derived chemicals). 

Acetylene dicarboxylic esters and (less easily) acetylene monocarboxylic esters replace nitriles from the 4,5-positions of 1,2,4,3-triazaphosphole rings (92) to give carboxyl derivatives of 1,2,3-diazaphospholes, presumably by a cycloaddition/cycloreversion mechanism, R/R = Me/Ph, SiMej/NMCj <83ZN(B)1484>. 

Scheme 43 shows the details of the different steps involved in the equilibrium. The nucleophilic attack of the P(III) derivative on the acetylenic bond yields a 1,3-dipole which, after a fast protonation, frees aZ ion. If the subsequent addition of this ion occurs on the P atom (reaction a), a P(V) phosphorane is formed, but the addition of Z on the ethylenic C atom (reaction b) results in the formation of an ylide. Both of these reactions occur under kinetic control and, in both cases, X is always an OR group from the initial acetylene dicarboxylic ester. When the acetylenic compound is a diketone and X is an alkyl or aryl moiety, the C=0 group is much more electrophilic and the attack by the Z ion produces an alcoholate (reaction c), a new intermediate which can cyclize on to the P+ to form a phosphorane, or attack the a-C atom to form an ylide as in Scheme 42. Hence, reactions a and c can coexist, and are strongly dependent on the nature of the trapping reagent and of the P compound, but reaction b is blocked, whatever the reagent. This is well illustrated by the reaction of the 2-methoxytetramethylphospholane 147 on diben-zoylacetylene in the presence of methanol as trapping reagent. The proportions of the vinylphosphorane 157 and spirophosphorane 158 formed (Figure 24) are 13% and 84%, respectively.

Several cycloaddition reactions of 2,5-dihydrothiophene derivatives have been reported. Compounds possessing an enamine system undergo [2 + 2] cycloaddition with acetylene-dicarboxylic ester (Scheme 215) (77AHC(2l)253). Diels-Alder addition of the 2,5-di-hydrothiophene-3-carboxylic ester (557) with butadiene, followed by desulfurization, leads to the trisubstituted cyclohexane (558) (B-74MI31404). 

Acrylic acid [79-10-7] - [AIR POLLUTION] (Vol 1) - [ALDEHYDES] (Vol 1) - [ALLYL ALCOHOL AND MONOALLYL DERIVATIVES] (Vol 2) - [MALEIC ANHYDRIDE, MALEIC ACID AND FUMARIC ACID] (Vol 15) - [POLYESTERS, UNSATURATED] (Vol 19) - [FLOCCULATING AGENTS] (Vol 11) - [CARBOXYLICACIDS - SURVEY] (Vol 5) -from acetylene [ACETYLENE-DERIVED CHEMICALS] (Vol 1) -from acrolein [ACROLEIN AND DERIVATIVES] (Vol 1) -acrylic esters from [ACRYLIC ESTER P OLYMERS - SURVEY] (Vol 1) -from carbon monoxide [CARBON MONOXIDE] (Vol 5) -C-21 dicarboxylic acids from piCARBOXYLIC ACIDS] (Vol 8) -decomposition product [MAT. ETC ANHYDRIDE, MALEIC ACID AND FUMARIC ACID] (Vol 15) -economic data [CARBOXYLIC ACIDS - ECONOMIC ASPECTS] (Vol 5) -ethylene copolymers [IONOMERS] (Vol 14) -in floor polishes [POLISHES] (Vol 19) -in manufacture of ion-exchange resins [ION EXCHANGE] (V ol 14) -in methacrylate copolymers [METHACRYLIC POLYMERS] (Vol 16) -in papermaking [PAPERMAKING ADDITIVES] (Vol 18)... 

Acetylenecarboxylic esters, reactions with nitrogen-containing heterocycles, 23, 263 Acetylenic derivatives of pyrazoles, synthesis and properties of, 82, 1 Acetylenic esters, synthesis of heterocycles through nucleophilic additions to, 19,297 Acid-catalyzed polymerization of pyrroles and indoles, 2, 287... 

Cyclic active-methylene compounds react in Michael reactions not only with a,/J-unsaturated acceptors, but also with acetylene dicarboxylates, propiolates, and their derivatives (Scheme IV/8). If, for instance, acetylene carboxylic esters are added to a variety of cyclic-active methylene compounds, ring-expanded products generally are formed directly. In other cases, it is possible to isolate the intermediate cyclobutene derivatives, which can be converted to the ring enlarged compounds in a second reaction step. 

The reaction of nitronic acid esters with acetylene derivatives yielded a2iri-dines(36d)(186]. 

Syntheses and properties of acetylenic derivatives of pyrazoles 02AHC(82)1. Syntheses of 2-pyrazolines by the reactions of a,/ -unsaturated aldehydes, ketones, and esters with diazoalkanes, nitrile imines, and hydrazines 02JHC1. 

In the search for chemicals inhibiting the enzymes O-methyl transferase and methyl farnesoate epoxidase, responsible for the methyl ester formation and for the terminal epoxidation in juvenile hormone biosynthesis. Brooks and co-workers (1984) prepared a number of acetylenic esters and 1,3-benzodioxole derivatives. These groupings are of particular interest in the context of JH biosynthesis inhibition. The acetylenic derivative 79 showed the strongest inhibitory action on both enzymes. 

Ethylene from acetylene derivatives s. 1, 59 Alcohols from a,/ -ethvlenecarboxylic acid esters s. 4, 91 CiC —C C... 

A further type of degradation occurs during the photolysis or thermolysis of derivatives of the 2,3-oxaphosphabicyclo[2.2.2]octene system, formally derivatives of cyclic phos-phonic or phosphinic acids. The compounds 42 are obtained by Baeyer-Villiger oxidations, with 3-chloroperoxybenzoic acid, of the 1 1 adducts from monomeric l//-phospho-les and iV-phenylmaleimide, and 43 by the identical oxidation of the products of dimerization of monomeric but unstable li/-phospholes. The simpler substrates 44, similarly obtained by the oxidation of the Diels-Alder adducts prepared from acetylene dicarboxylic ester, have also been examined. The thermolysis (at 80-110 °C in toluene) or... 

Acetylenic ethers and esters represent an important class of functionalized acetylene derivatives of the hypothetical alkynols, RC=COH. The chemistry of acetylenic ethers has been well developed since their first preparation about 100 years ago Several exhaustive reviews covering the literature on acetylenic ethers and their analogs up to 1985 have been published in the last 30 years. In contrast to acetylenic ethers, esters of alkynols were unknown until the mid-1980s when the first preparation of alkynyl tosylates was reported. In the following years a wide variety of alkynyl carboxylate, phosphate and sulfonate esters has been prepared from alkynyl iodonium salts. The chemistry of these novel derivatives of alkynols has been summarized in a recent review. In the last 10 years considerable interest and research activity has arisen toward alkynols themselves and such derivatives as alkynolate salts and silyl ynol ethers. The present chapter will cover the chemistry of acetylenic ethers and esters as well as related derivatives of ynols with emphasis on new developments in this subject during the last 5-10 years. 

Acidic hydrolysis of the reactive enamide led to the corresponding carboxylic acids 14 whereas alcoholysis gave esters 16 and aminolysis amides 15. The mechanism of the hydrolysis was shown to proceed via miinchnone derivatives 20 which, instead of being opened with a nucleophile, reacted as a 1,3-dipole in [3+2] cycloaddition reactions with propiolic esters or acetylene dicarboxylic esters to give after elimination of carbon dioxide protected pyrroles 19 (Scheme 3.2.4)... 

The stepwise (room temperature/thermal) cycloreversion sequence failed to provide furans from acetylene derivatives activated by just a single electron withdrawing moiety (e.g. propiolate esters). These derivatives, less reactive than DMAD, did not undergo cycloadditions to the immobilised dipoles at an appreciable rate at room temperature. 

Lie Ken Jie, M.SE., Pasha, M.K., and Alam, M.S. (1998) S3m-thesis of Novel Triazole Fatty Acid Derivatives from Acetylenic Fatty Ester, Chem. Phys. Lipids 97,71-78. 

The a-pyrone analogues (101) have been synthesized by a [24]cycloaddition reaction between cyclic a-keto-enamines (100) and di(thioethyl)ketene/ 5-Enamino- 8-keto-esters, derived from the corresponding acetylenic keto-esters, undergo smooth alkylation to give /35-diketo-esters, which can be cyclized to 4-hydroxy-a-pyrones with hot polyphosphoric acid/ ... 

A novel insoluble green complex of palladium(II) and N,N -salicylideneethylenedi-amine (salen) functions as a selective heterogeneous catalyst, notably for the reduction of alkynes in the presence of alkenes, and of the latter in the presence of certain functional groups. E ciVEthylene from acetylene derivs. A soln. of startg. acetylene deriv. in EtOH hydrogenated for 17 min in the presence of the palladium(ll) complex (prepared from potassium tetrachloropalladate, salen, and triethylamine) cis-product. Y 100%. Reduction of alkenes is considerably slower however, terminal olefins may be reduced in the presence of internal olefins esters, oxo compds., dibenzyl ether, and iodobenzene were unaffected. F.e., also ar. amines from nitro compds. s. J.M. Kerr et al.. Tetrahedron Letters 29, 5545-48 (1988). 

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