Presence Of Dimethyl Acetylenedicarboxylate Research Articles

ChemInform Abstract: A Comparison of 4‐Oxazoline and 2‐Acylaziridine Routes to Azomethine Ylides.

AbstractThermolysis of the aziridines such as (I) or (VI) in the presence of dimethyl acetylenedicarboxylate (II) yields pyrrolines such as (III) or (VII), pyrroles such as (IV), or enamines such as (V) via the intermediate azomethine ylides.

Synthesis of heterodinuclear FeRu(CO) 6(R-DAB(6e))(R-DABRNC(H)C(H)NR) Part XV. Comparison of the reactivities of heterodinuclear FeRu(CO) 6(R-DAB(6e)) and homodinuclear analogues M 2(CO) 6(R-DAB(6e)) (M = Fe, Ru). Single-crystal x-ray structures of FeRu(CO) 6(i-Pr-DAB(6e)) and FeRu(CO) 5(i-Pr-DAB(4e))(C 3H 4)

The reactions of Fe(CO) 3(R-DAB; R 1, H(4e)) ( 1a: R = i-Pr, R 1 = H; 1b: R = t-Bu, R 1 = H; 1c: R = c-Hex, R 1 = H; 1e: R = p-Tol, R 1 = H; 1f: R = i-Pr, R 1 = Me) with Ru 3(CO) 12 and of Ru(CO) 3(R-DAB; R 1, H(4e)) ( 2a: R = i-Pr, R 1 = H; 2d: R = CH(i-Pr) 2, R 1 = H) with Fe 2(CO) 9 in refluxing heptane both afforded FeRu(CO) 6(R-DAB; R 1, H(6e)) (3) in yields between 50 and 65%. The coordination mode of the ligand has been studied by a single crystal X-ray structure determination of FeRu(CO) 6(i-Pr-DAB(6e)) ( 3a). Crystals of 3a are monoclinic, space group P2 1/ a, with four molecules in a unit cell of dimensions: a = 22.436(3), b = 8.136(3), c = 10.266(1) Å and β = 99.57(1)°. The structure was refined to R = 0.049 and R w = 0.052 using 3045 reflections above the 2.5σ( I) level. The molecule contains an FeRu bond of 2.6602(9) Å, three terminally bonded carbonyls to Fe, three terminally bonded carbonyls to Ru and bridging 6e donating i-Pr-DAB ligand. The i-Pr-DAB ligand is coordinated to Ru via N(1) and N(2) occupying an apical and equatorial site respectively (RuN(1) = 2.138(4) RuN(2) = 2.102(3) Å). The C(2)N(2) moiety of the ligand is η 2-coordinated to Fe with C(2) in an apical and N(2) in an equatorial site (FeC(2) = 2.070(5) and FeN(2) = 1.942(3) Å). The 1H and 13C NMR data indicate that in all FeRu(CO) 6(R-DAB(6e)) complexes ( 3a to 3f) exclusively η 2-CN coordination to the Fe atom and not to the Ru atom is present irrespective of whether 3 was prepared by reaction of Fe(CO) 3(R-DAB(4e)) ( 1) with Ru 3(CO) 12 or by reaction of Ru(CO) 3(R-DAB(4e)) ( 2) with Fe 2(CO) 9. In the case of FeRu(CO) 6(i-Pr-DAB; Me, H(6e)) ( 3f) the NMR data show that only the complex with the C(Me)N moiety of the ligand σ-N coordinated to the Ru atom and the C(H)N moiety η 2-coordinated to the Fe atom was formed. Variable temperature NMR experiments up to 140 °C showed that the α-diimine ligand in 3a is stereochemically rigid bonded. FeRu(CO) 6(R-DAB(6e)) ( 3a and 3e) reacted with allene to give FeRu(CO) 5(R-DAB(4e))(C 3H 4) ( 4a and 4e). A single crystal X-ray structure determination of FeRu(CO) 5(i-Pr-DAB(4e))(C 3H 4) ( 4a) was performed. Crystals of 4a are triclinic, space group P1, with two molecules in a unit cell of dimensions: a = 9.7882(7), b = 12.2609(9), c = 8.3343(7) Å, α = 99.77(1)°, β = 91.47(1)° and γ = 86.00(1)°. The structure was refined to R = 0.028 and R w = 0.043 using 4598 reflections above the 2σ( I) level. The molecule contains an FeRu bond of 2.7405(7) Å and three terminally bonded carbonyls to iron. Two carbonyls are terminally bonded to the Ru atom together with a chelating 4e donating i-Pr-DAB ligand [RuN = 2.110(1) (mean)]. The allene ligand is coordinated in an η 3-allylic fashion to the Fe atom while the central carbon of the allene moiety is σ-bonded to the Ru atom (FeC(14) = 2.166(3), FeC(15) = 1.970(2), FeC(16) = 2.127(3) and RuC(15) = 2.075(2) Å). The 1H and 13C NMR data show that in solution the coordination modes of the R-DAB and the allene ligands are the same as in the solid state. Thermolysis reactions of 3a with R-DAB or carbodiimides gave decomposition and did not afford C(imine)C(reactant) coupling products. Thermolysis reactions of 3a with M 3(CO) 12 (M = Ru, Os) and Me 3NO gave decomposition. When the reaction of 3a with Me 3NO was performed in the presence of dimethylacetylenedicarboxylate (DMADC) the known complex FeRu(CO) 4(i-Pr-DAB(8e))(DMADC) ( 5a) was formed in low yield. In 5a the R-DAB ligand is in the 8e coordination mode with both the imine bonds η 2-coordinated to iron. The acetylene ligand is coordinated in a bridging fashion, parallel with the FeRu bond.

Carbonyl‐Ylide als Cycloadditionspartner: Intramolekularer Transfer einer ADM‐Einheit

Carbonyl Ylides as Cycloaddition Components: Intramolecular Transfer of a DMAD UnitOn heating the specifically designed ene‐oxirane 6 is cleanly transformed into the 2,5‐dihydrofuran derivative 7 As mechanism of this conversion ring opening to carbonyl ylide 8 is proposed followed by formation of the intramolecular cycloadduct 9 which suffers rapid cycloreversion leading to 7. The latter process is precluded in the case of the dihydro derivative 10 which, in fact, reacts under comparable conditions and with equally good yield to give 11 as a thermally stable and sterically pure compound. In the presence of dimethyl acetylene dicarboxylate (DMAD) as external dipolarophile bimolecular cycloadditions do not compete with the intramolecular reaction mode.

Photochemistry of benzisothiazoles in the presence of dimethyl acetylenedicarboxylate

1,2-Benzisothiazole gave upon irradiation in the presence of dimethy acetylenedicarboxylate a mixture of cis - and trans - substituted phenylthioalkenes (II) and 7-cyano-2,3-dicarboxybenzothiophene.

An investigation of the reaction of primary nitroalkanes with acetic anhydride/sodium acetate

Oxidation of primary nitroalkanes by acetic anhydride/sodium acetate has been found to be more complex than previously suspected. Phenylnitromethane, with acetic anhydride/sodium acetate at 60–80°, for example, gives a mixture of benzoic anhydride, triacethylhydroxylamine and acetanilide, through the mixed anhydride ▪ as a key intermediate. Evidence in support of this latter species has been obtained by carrying out the oxidation in the presence of dimethyl acetylenedicarboxylate as a 1,3-dipolarophile, when 3-phenyl-4,5-dicarbomethoxyisoxazole is formed in 82% yield. A number of other 3-alkyl- and 3-aryl-4,5-dicarbomethoxyisoxazoles have been prepared in a similar manner.

Synthesis of poly(vinylene azoarylenes) by decomposing aromatic bis-diazo compounds in the presence of dimethylacetylene dicarboxylate (DMADC)

Synthesis of poly(vinylene azoarylenes) by decomposing aromatic bis-diazo compounds in the presence of dimethylacetylene dicarboxylate (DMADC)