Propiolic add

Methyl propiolate Propiolic add, methyl ester (8) 2-Propynoic add, methyl ester (9 (922-67-8)... 

Potassium hydroxide, 20, 239, 303-304 Potassium persulfate, 274 Potassium superoxide, 304-307 Potassium tri-sec-butylborohydride, 307 Prins reaction, 159 Progesterone, 107 Proline, 10, 307 1,3-Propanediol, 37 Propargylic alcohols, 8, 53 Propargylic chlorides, 155 (E)-Propenyllithium, 141 Propiolaldehyde diethyl acetal, 79-80 Propiolamidium salts, 124 Fropiolate esters, 8 Propiolic add, 295 Propylene carbonate, 74 Propylene oxide, 74 Protolichesterinic add, 412 Pterocarpins, 114 Pulegone, 287, 288, 308-309 tosylhydrazones, 375-376 Pulvinic acid pigments, 291 Pumiliotoxin, 28... 

Photochemistry.— The photochemical addition of dimethyl acetylene-dicarboxylate, methyl propiolate, or methyl phenylpropiolate to benzo[h]-thiophen and its 2- and 3-methyl and 2,3-dimethyl derivatives leads to cyclobutene derivatives of unexpected structures. From benzo[ >]-thiophen and dimethyl acetylenedicarboxylate (376) is obtained. Methyl propiolate adds in a direction opposite to that of methyl phenylpropiolate, suggesting that the excited state of benzo[h]thiophen is highly polarized. The mechanism of the addition is discussed, and several mechanistic alternatives are suggested. Only with diphenylacetylene, which reacts slowly, can the normal addition product (377) be obtained. The... 

Acyl azides 268, derived from furan, thiophene and selenophene, add slowly at room temperature to the strained double bond of 5-methylenebicyclo[2.2.1]hept-2-ene. Two regioisomeric triazolines, 269 and 270, which form in the first step, are unstable and decompose with elimination of nitrogen to provide aziridine derivatives 271. Products 271 are isolated in good yield (73-85%). It is worthy to note that not only the terminal, unstrained double bond in the starting material, 5-methylenebicyclo[2.2.1]hept-2-ene, is unaffected, but also the typical dipolarophiles like esters of crotonic, propiolic and byt-2-ynoic acids do not react with azides 268 under these conditions (Scheme 39) <2002J(P1)1420>. 

The A pyrroline-A-oxides (SO) undergo violently exothermic reactions with DM AD in the absence of solvent.95 In ether at room temperature, unstable products (51) that rearrange exothermically to the pyrrolines (52) are formed this ring fission recalls that of isoxazolium salts.96 With unsymmetrical acetylenes, two modes of cycloaddition are possible. Propiolic acid adds to 50 (R = H), giving an unstable solid... 

Methyl propiolate and EPP add to indolizine giving 43 and 44 the structure of the latter was confirmed by hydrolysis and decarboxylation to a known compound.597 Substituted indolizines react as well Boekel-heide and Fahrenholtz converted 2-phenylindolizine (47) into 48 under these same conditions.599... 

Trialkylphosphines add via anti addition to give the expected salts (577 Scheme 81) which decompose upon work-up to products (578) not containing phosphorus.145 Triethyl phosphite (equation 132) reacts with propiolic acid (572) or methyl propiolate (506) to give predominately (>90%) the P-phos-phono ester (579) with the ( -configuration.l4Sb... 

Alkynoic acids in which the C—C triple bond is far removed from the acid moiety behave like simple alkynes. 63,166 Propiolic acid, on the other hand, adds HBr to form almost exclusively (Z)-3-bromoprope-noic acid (equation 115).98... 

From the Fischer rate study, it appears that primaiy ester-substituted radicals are not electrophilic but ambiphilic and the borderline between ambiphilic and electrophilic radicals is not at all clear. Consider our results68 (Scheme 16) on the atom transfer additions of ester-substituted radicals to alkynes (with the caution that it may be dangerous to compare yields in place of rate constants). The primary ester-substituted radical adds more efficiently to 1-heptyne but the tertiary ester-substituted radical prefers ethyl propiolate. 

Addition of allylic sulfides to methyl propiolate. In the presence of AlClj (1 ftpiiv ). ullylic sulfides add in Michael fashion to methyl propiolate followed by a t t igninliopic rearrangement.7... 

Bryce-Smith and Lodge [3] have discovered that methyl propiolate, dimethyl acetylenedicarboxylate, and phenylacetylene add to benzene upon irradiation at 50°C. The products are cyclooctatetraenes, formed via initial ortho addition of the acetylene to benzene followed by ring opening (Scheme 9). 

A two-phase mixture ol methyl propiolate (5.0 g, 59.5 mmol), boric add (5.5 g, 89 mmol), sodium benzenesulfinate (9.75 g, 59.5 mmol), and tetra-n-butylammonium hydrogen sulfate (3.0 g, 8.75 mmol) (Note 1) in tetrahydrofuran water (200 mL, 1 1) is stirred vigorously at room temperature for 48 hr (Note 2). The solution is acidified to pH 4 (2 N hydrochloric acid) and extracted into diethyl ether (4 x 50 mL) (Note 3). The organic layer is dried (MgSCU) and concentrated under reduced pressure to afford 13.75 g of yellow oil (Note 4) which is subjected to flash column chromatography (1.5 1 hexanes-diethyl ether) to afford initially methyl (E)-3-(benzenesulfonyl)prop-2-enoate (400 mg, 2.9%) and then the desired Z-isomer (10.89 g, 81%) as a pale yellow solid, pure by spectral study (Note 5). 

Methyl propiolate and DMAD add to carbon diselenide under high pressure to give 1,4,5,8-tetraselenafulvalenes (101) and (102). The dimerization of a l,3-diselenole-2-carbene is implicated (81CC669). The alkynes function as the two-atom unit while carbon diselenide is the three-atom unit. 

The addition of hydrogen halides to propiolic acid (6 of Table 2) in water occurs by a mechanism entirely different from that of the acid-catalysed hydration of phenylpropiolic acid (see above). Here again vinyl cations are probably not involved as intermediates and the major mechanistic pathway is the one involving formation of 17 which stereospecifically adds a proton to form tram adducts following equation (7). 

Prior to 1973, nitrones were believed to add to monosubstituted dipolarophiles in a unidirectional fashion, giving 5-substituted adducts exclusively (Fig. 7). An exception to this behavior was reported by Huisgen a mixture of 4- and S-substituted isoxazolines form in the reaction of methyl propiolate with C-phenyl-N-methylni-trone19, as shown in Fig. 7. 

Sodium iodide, 99%, was purchased from Janssen Chimica and used as received. Glacial acetic add, 99%, was purchased from Prolabo. Ethyl propiolate was obtained from Janssen Chimica and used as received. 

The related (Z)-lithium dialkenylcuprates (147) derived from acetylene itself also react well with epoxides to provide a useful route to (2)-homoallylic alcohols the lack of reactivity with esters allows an easy access to lactones (148) by condensations between epoxy esters and this type of cuprate (Scheme 29). Likewise, the lower homologs (149) and (151), both of which are relatively easy to prepare in optically active forms, can be readily converted into homoallylic and bishomoallylic alcohols (150) and (152) respectively. An ester unit can also be incorporated into the cuprate functions thus, addition of a mixed lithium cuprate, RCuYLi , to ethyl propiolate gives the cuprates (153), which add to epoxides to give unexpectedly the (Z)-crotonates (154). Such isomerization is not uncommon with vinyl carbanions in general, and is obviously a limitation when isomeric mixtures are produced. 

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