F Methyl propiolate

Hexadiynylene chlorosulfite, 2155 Lithium ethynediolate, 0989 f Methoxyacetylene, 1143 3-Methoxypropyne, 1520 f Methyl propiolate, 1438... 

Several syntheses of the hepatatoxic alkaloid (+)-retronecine have been reported although the most succinct has utilized a chiral azomethine ylide cycloaddition to construct the bicychc skeleton. The ylide processor 175, which was obtained in five efficient steps from commercially available tran -(l )-4-hydroxy-L-proline, underwent double desilyation in the presence of AgF (described in detail in Section 3.1.1) and in situ cycloaddition with methyl propiolate, to deliver a 3 1 mixture of cycloadducts in favor of the desired regioisomer. DiisobutyMuminum (DIBAL) reduction of 176 furnished enantiopure (-F)-retronecine (Scheme 3.50). 

Methyl-5-propyl-1,2-4-trioxolane, see trans-2-Hexene ozonide, 2507 f Methyl propynoate, Methyl propargylate, see Methyl propiolate, 1438... 

The promotion of polymerization of certain alkynes by nucleophiles is another Kiev contribution of the late 1960s polypropiolanhydride of molecular weight 12000 could be produced elsewhere (see Section III.F) are mentioned other anions that promote both trimerization and polymerization of methyl propiolate . 

Aminoindoxazene differs from related 3-aminobenzodiazoles in that it undergoes nonregiospecific cycloaddition of methyl propiolate to give a mixture of 2-oxo-2ff-pyrimido- and 4-oxo-4/f-pyrimido[ 1,2-h]benzisox-azole.75... 

Indolenines exemplified by compound (336) can be converted into the related 3/f-indole 1-oxide (338) by a sequence involving reduction to the dihydro compound (337) followed by oxidation with /M-chloroperbenzoic acid. Compound (338) behaves as a typical cyclic nitrone and undergoes cycloaddition with DMAD and methyl propiolate. The initially formed cycloadduct (339) rearranges via an aziridine intermediate to an oxazolo[3,2-a]indole (340) (Scheme 107) <93JCS(Pl)939>. 

Methyl propiolate added dropwise with shaking and ice-cooling to a soln. of 1-methylbenzimidazole 3-oxide in chloroform, and allowed to stand 1 hr. at room temp. methyl a-formyl-l-methyl-2-benzimidazoleacetate. Y 90%. F. e. s. S. Takahashi and H. Kano, Ghem. Pharm. Bull. 12, 1290 (1964). 

Scheme 6.1 Total synthesis of (/f)-ochratoxin a (326) as well as ochratoxins A-C (323-325). Reagents and conditions a) ketene dimethyl acetal, sealed tube, 165°C, 23 h b) methyl propiolate, sealed tube, 145 C, 22 h, 69% over two steps c) p-TsOH, CH2CI2, rt, 72 h, 82% d) BCI3, CH2CI2, 0°C, 10 min, 92% e) SO2CI2, CH2CI2, rt, 48 h f) MeOH, LiOH H20, reflux, 5 h, 68% over two steps g) L-phenylalanine t-butyl ester, EEDQ, THF, rt, 15 h h) EtOH...

Benzaldehyde, methyl propiolate, NH4-acetate, and acetic acid heated 10-15 min. on a steam bath dimethyl l,4-dihydro-4-phenylpyridine-3,5-dicarboxylate. Y 79%. F. e. s. T. Chennat and U. Eisner, Soc. Perkin I 1975, 926. 

Tetramerization. Methyl propiolate in cyclohexane stirred at 22 in the presence of tetrakis (phosphorus trichloride) nickel (0), and the product isolated after ca. 15 min. crude 1,2,4,6-tetracarbomethoxycyclooctatetraene. Y 83% based on startg. m. consumed.—The reaction, catalyzed by zero valent complexes, is extremely limited in scope. It provides, however, a useful route to a rare class of compounds. F. e. s. J. R. and M. F. Leto, Am. Soc. 83, 2944 (1961). 

Methyl propiolate in benzene treated with p-chlorobenzaldehyde and BFg-etherate in the same solvent, HgS passed into the soln. for 5 min., stirred and refluxed 0.5 hr. methyl 2,4-di-p-chlorophenyl-m-dithiin-5-carboxylate. Y ca. 100%. F. e. and limitations s. U. Eisner and T. Krishnamurthy, Tetrahedron 27, 5753 (1971) review of dithiins s. Intern. J. Sulfur Chem. B 7, 101 (1972). 

Pyrroles. Triethylamine in benzene added dropwise to a soln. of N-(4-nitro-benzyl)benzimidodiloride in benzene and methyl propiolate, stirring continued 1 hr. methyl 2-phenyl-5-(4-nitrophenyl)pyrrole-4-carboxylate. Y 63%. F. e. s. R. Huisgen et al., B. 105, 1258, 1279, 1307 (1972). 

Carbomethoxy-4,5-dihydro-6H-l,2-oxazine N-oxide dissolved with stirring and cooling in methyl propiolate, allowed to stand 24 hrs. at ca. 20°, and excess methyl propiolate removed by vacuum distillation product. Y 92%. F. e. s. I. E. Chlenov et al., Izvest. 1973, 473 C. A. 79, 5304. 

Methyl-5H-dibenzophosphole in tetrahydrofuran added dropwise at 0° under Ng during 10 min. to methyl propiolate in tetrahydrofuran-water, and refluxed 12 hrs. -> 5,6-dihydro-6-methoxycarbonylmethyl-5-methyldibenzo[b,d]phosphorin 5-oxide. Y 70%. F. e. s. E. M. Richards and J. C. Tebby, Soc. (C) 1971, 1064. 

An alternative approach to alkene extended cyclohexadienyliumiron complexes is the reaction of (a-keto-cyclohexa-l,3-diene)iron complexes with a nucleophile obtained by hydroalumination of methyl propiolate, subsequent ligand exchange with triphenyl-phosphane, and removal of the hydroxy group with hexafluorophosphoric acid (Scheme 4-171). Organocuprates add to these compounds at the terminus of the noncomplexed double bond.f "" ... 

Disubstituted acetylenes and 1,2-disubstituted olefins are comparatively bad dipolarophiles. If the introduction of the second substituent was expected to have a strong accelerating effect, this is lacking (fumaric ester is sometimes less reactive than acrylic ester) or is small, c.f. acetylene dicarboxylate with propiolates. When the second substituent is a phenyl group, it deactivates phenylpropiolate is less reactive than propiolate in reaction types (i) (ii) and (iv). Table 13. The introduction of methyl groups into the a or )3 position of acrylic ester, has a similar effect on the rate of several different 1,3-cycloadditions". Steric hindrance appears to intervene in these cases. 

Azapyrrocolines. A soln. of l-amino-2-picolinium iodide in dimethylformamide stirred 1 hr. at room temp, with solid K-carbonate, a soln. of ethyl propiolate in the same solvent added dropwise with stirring, which is continued 1 hr. at room temp. l-carbethoxy-5-methyl-3-azapyrrocoline. Y 55%. F. e. and limitation s. V. Boekelheide and N. A. Fedoruk, J. Org. Chem. 55, 2062 (1968) cf. R. Grashey and M. Baumann, Tetrah. Let. 1969, 2173. 

Methyl 2,3,4-tri-0-benzyl-L- /Fcero-p-D-a//o-heptopyranoside, H-32 Methyl 2,3,4-tri-O-benzyl-L- /Fcero-a-D- /wco-heptopyranoside, H-42 Methyl 4,5,7-tri-0-benzyl-a-D- iiwco-2-heptulopyrajiosonate, H-64 Methyl 2,3,6-tri-0-benzyl-a-D-x /o-hexopyTaiiosid-4-ulose, H-104 Methyl 3,4,6-tri-O-benzyl-D-mannopyranoside, M-204 Methyl 3,4,6-tri-0-benzyl-2-0-mesyl-p-D-maimopyranoside, M-205 Methyl 2,3,5-tri-0-benzyl-f(-D-ribofuranoside, M-208 Methyl 3-(2,3,5-tri-0-benzyIribofuranosyI)propiolate, M-212 Methyl 2,4,6-tri-0-benzyl-3-0-(3,4,6-tri-0-benzyl-p-D-mannopyranosyl)-a-D-mannopyranoside, M-97... 

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