Orthoamide und Iminiumsalze, LXXXIII [1]. Die Synthese von starken Formylierungsmitteln im präparativen Großmaßstab: Triformamid (Triformylamin) / Orthoamides and Iminium Salts LXXXIII [1]. The Synthesis of Strong Formylating Reagents on Large Preparative Scale: Triformamide (Triformylamine)

The preparation of sodium diformamide (7) from formamide and sodium methanolate under azeotropic removal of methanol with cyclohexane, or from formamide and sodium ethanolate in ethanol, is described. Diformamide (8) can be prepared by treatment of sodium diformamide (7) with formic acid. Triformamide (triformylamine) (1) is formed in the reaction of sodium diformamide with inorganic acid halides such as SOCl2, SO2Cl2 or PCl3 in acetonitrile at low temperatures. Triformamide (1) can be prepared on a large scale by the action of methanesulfonyl chloride on finely powdered sodium diformamide (7) in acetonitrile. Tris(diformylamino)methane (4) can be formed as a side product. A procedure was developed for the large-scale preparation of N;N-diformylacetamide (6) from sodium diformamide and acetyl chloride. Triformamide (1) can be prepared from N;Ndiformylacetamide (6) and diformamide with good yields

Orthoamide und Iminiumsalze, LXXXI [1]. Orthoamid-Derivate der 1,3-Dimethylparabansäure / Orthoamides and Iminium Salts LXXXI [1]. Orthoamide Derivatives of 1,3-Dimethylparabanic Acid

1,3-Dimethyl-5-imino-imidazolidine-2,4-dione (7a) undergoes thiolysis (H2S) to give the corresponding imidazolidine-2,4-dione-5-thione derivative 6. The 5-N-methylimino analogue 7b can be obtained from 7a by methylation. Further methylation of 7b affords the crude iminium salt 8c from which the heterocyclic orthoamide derivatives 10, 11 can be prepared. The heterocyclic amide acetal 9a can be obtained from 7a and dimethyl sulfate in methanol and subsequent addition of sodium methanolate in a one-pot reaction. The aminal ester 10 is converted to the amide acetal 9a on treatment with hydrogen chloride in methanol

Dimethylaminomethylene-α-D-xylo-hept-5-ulofuranurononitrile as Building Block in the Synthesis of ‘Reversed’ C-Nucleoside Analogues

3-O-Benzyl-6-deoxy-1,2-O-isopropylidene-6-(dimethylaminomethylene)-α-D-xylo-hept-5-ulofuranurononitrile (1) was reacted with amidinium salts, S-methylisothiouronium sulfate, and guanidinium chloride, respectively, in the presence of bases to furnish the 4-(3-O-benzyl-1,2-O-isopropylidene- α-D-xylo-tetrofuranos-4-yl)pyrimidine-5-carbonitriles 2 and the 4-(1,2-O-isopropylidene- α-D-glycero-tetr-3-enofuranos-4-yl)pyrimidine-5-carbonitriles 3, respectively. Treatment of 1 with ethyl 5-aminopyrazole-4-carboxylates yielded the ethyl 7-(3-O-benzyl-1,2-O-isopropylidene- α-D-xylo-tetrofuranos-4-yl)-6-cyanopyrazolo[1,5-a]pyrimidine-3-carboxylates 4 and the ethyl 7-amino-6-(3-O-benzyl-1,2-O-isopropylidene-α-D-xylo-pentofuranuronoyl)pyrazolo[1,5-a]pyrimidine- 3-carboxylates 5, respectively. Reaction of 1 with 2-benzimidazolylacetonitrile in the presence of sodium methanolate afforded 1-amino-2-(3-O-benzyl-1,2-O-isopropylidene-α-D-xylo-pentofuranuronoyl) benzo[4,5]imidazo[1,2-a]pyridine-4-carbonitrile (6) and 1-amino-2-(3-deoxy-1,2-O-isopropylidene- α-D-glycero-pent-3-enofuranuronoyl)benzo[4,5]imidazo[1,2-a]pyridine-4-carbonitrile (7).

Fragmentation of Suberin and Composition of Aliphatic Monomers Released by Methanolysis of Cork from Quercus suber L.,Analysed by GC-MS, SEC and MALDI-MS

Summary Suberin from extractive-free cork from Quercus suber L. was depolymerised by methanolysis using different sodium methanolate (NaOMe) concentrations. 1% and 3% NaOMe completely removed suberin from cork (54%–56% of extractive-free cork), but for lower concentrations there was incomplete solubilisation; with 0.05% NaOMe, only approximately 80% of total suberin was removed. The monomeric composition of the extracts differed significantly: for the 0.05% NaOMe, only alkanoic acids and diacids were found; the yield of v-hydroxy acids increased with reactant concentration, as well as alkanols and ferulic acid. Results from light scattering, SEC and MALDI-MS showed that soluble oligomeric fragments containing suberinic acids were present in the methanolysis mixture. The molecular weight of these oligomeric fragments decreased with higher sodium methanolate concentrations.

Kinetics of Methanolysis of Substituted Benzamide O-(Phenoxycarbonyl)- and O-(Alkoxycarbonyl)oximes Catalyzed by Sodium Methanolate

The kinetics of methanolysis of substituted benzamide O-(phenoxycarbonyl)- and O-(alkoxycarbonyl)oximes catalyzed by sodium methanolate was studied at 25 °C. The reaction proceeds in two steps. In the first, faster step, the substituted phenoxy group is exchanged for a methoxy group giving rise to substituted O-(methoxycarbonyl)oximes. In the second step, a benzamide oxime is eliminated and dimethyl carbonate is formed. The slope of the plot of the rate constant in dependence on the sodium methanolate concentration has an increasing tendency in both steps. In the presence of 18-crown-6, the plots are linear and the rate constants are lower than in the absence of the crown ether. The rate constants of the reaction of the substrate with the methanolate ion and with the MeONa ion pair were determined assuming that the sodium cation-catalyzed reactions constitute the rate-determining step of the reaction of the substrate with the MeONa ion pair. For the elimination of the aryloxy group and of the substituted benzamide oxime, the rate constants of the reaction with the ion pair are roughly twelvefold and twentyfold higher, respectively, than in the uncatalyzed reaction. The slope of the dependence of log k on the pKa of the substituted phenols (βlg) has the value of -0.52 for the uncatalyzed reaction of elimination of the substituted phenoxy group, -0.83 for the elimination of the benzamide oxime group, and -0.53 for the reaction with the ion pair. In the first step and probably also in the second step, the reaction proceeds by the concerted mechanism. The relatively high ρ value of methanolysis of substituted benzamide O-(4-nitrophenoxycarbonyl)oximes, 0.63, suggests that the structure of the transition state approaches that of the tetrahedral intermediate.