The disclosed embodiments detail improved methods for the synthesis of diketopiperazines from amino acids. In particular improved methods for the cyclocondensation and purification of N-protected 3,6-(aminoalkyl)-2,5-diketopiperazines from N-protected amino acids. Disclosed embodiments describe methods for the synthesis of 3,6-bis-[N-protected aminoalkyl]-2,5-diketopiperazine comprising heating a mixture of an amino acid in the presence of a catalyst in an organic solvent. The catalyst is selected from the group comprising sulfuric acid, phosphoric acid, p-toluenesulfonic acid, 1-propylphosphonic acid cyclic anhydride, tributyl phosphate, phenyl phosphonic acid and phosphorous pentoxide among others. The solvent is selected from the group comprising: dimethylacetamide, N-methyl-2-pyrrolidone, diglyme, ethyl glyme, proglyme, ethyldiglyme, m-cresol, p-cresol, o-cresol, xylenes, ethylene glycol and phenol among others.

The disclosure relates to a process for the dimerization of conjugated diene compounds by a heterogeneous catalytic process using a supported palladium catalyst in the presence of at least one palladium activator and at least one palladium coordinating agent.

The disclosed embodiments detail improved methods for the synthesis of diketopiperazines from amino acids. In particular improved methods for the cyclocondensation and purification of N-protected 3,6-(aminoalkyl)-2,5-diketopiperazines from N-protected amino acids. Disclosed embodiments describe methods for the synthesis of 3,6-bis-[N-protected am inoalkyl]-2,5-diketopiperazine comprising heating a mixture of an amino acid in the presence of a catalyst in an organic solvent. The catalyst is selected from the group comprising sulfuric acid, phosphoric acid, p-toluenesulfonic acid, 1-propylphosphonic acid cyclic anhydride, tributyl phosphate, phenyl phosphonic acid and phosphorous pentoxide among others. The solvent is selected from the group comprising: dimethylacetamide, N-methyl-2-pyrrolidone, diglyme, ethyl glyme, proglyme, ethyldiglyme, m-cresol, p-cresol, o-cresol, xylenes, ethylene glycol and phenol among others.

The disclosed embodiments detail improved methods for the synthesis of diketopiperazines from amino acids. In particular improved methods for the cyclocondensation and purification of N-protected 3,6-(aminoalkyl)-2,5-diketopiperazines from N-protected amino acids. Disclosed embodiments describe methods for the synthesis of 3,6-bis-[N-protected am inoalkyl]-2,5-diketopiperazine comprising heating a mixture of an amino acid in the presence of a catalyst in an organic solvent. The catalyst is selected from the group comprising sulfuric acid, phosphoric acid, p-toluenesulfonic acid, 1-propylphosphonic acid cyclic anhydride, tributyl phosphate, phenyl phosphonic acid and phosphorous pentoxide among others. The solvent is selected from the group comprising: dimethylacetamide, N-methyl-2-pyrrolidone, diglyme, ethyl glyme, proglyme, ethyldiglyme, m-cresol, p-cresol, o-cresol, xylenes, ethylene glycol and phenol among others.

Disclosed in the present invention is a preparation method for a tetra-substituted allenoic acid compound based on a palladium catalytic system, that is, a highly optically active allenoic acid compound having axial chirality is directly constructed in one step by reacting tertiary propargyl alcohol, carbon monoxide and water in an organic solvent under the action of a palladium catalyst, a chiral bisphosphine ligand, an organophosphoric acid, and an organic additive, and the theoretical yield can reach 100%. The method of the present invention is simple to operate, the raw materials and reagents are readily available, the reaction conditions are mild, the substrate universality is wide, the functional group compatibility is good, the reaction has high enantioselectivity (77%?96% ee), and the reaction is well compatible with complex natural products or substrates of a drug molecular skeleton. The highly optically active allenoic acid compound obtained by the present invention can be used as an important intermediate for constructing a ?-butyrolactone compound containing a tetra-substituted chiral quaternary carbon center, tetra-substituted allenol, tetra-substituted allenal, tetra-substituted allenyl ketone, tetra-substituted allenami de and other compounds.

The disclosed embodiments detail improved methods for the synthesis of diketopiperazines from amino acids. In particular improved methods for the cyclocondensation and purification of N-protected 3,6-(aminoalkyl)-2,5-diketopiperazines from N-protected amino acids. Disclosed embodiments describe methods for the synthesis of 3,6-bis-[N-protected aminoalkyl]-2,5-diketopiperazine comprising heating a mixture of an amino acid in the presence of a catalyst in an organic solvent. The catalyst is selected from the group comprising sulfuric acid, phosphoric acid, p-toluenesulfonic acid, 1-propylphosphonic acid cyclic anhydride, tributyl phosphate, phenyl phosphonic acid and phosphorous pentoxide among others. The solvent is selected from the group comprising: dimethylacetamide, N-methyl-2-pyrrolidone, diglyme, ethyl glyme, proglyme, ethyldiglyme, m-cresol, p-cresol, o-cresol, xylenes, ethylene glycol and phenol among others.

A continuous process for the preparation of propylene oxide, comprising providing a liquid feed stream comprising propene, hydrogen peroxide, methanol, water, at least one dissolved potassium salt of hydroxyethylidenediphosphonic acid, and optionally propane; passing the liquid feed stream provided in (i) into an epoxidation reactor comprising a catalyst comprising a titanium zeolite of structure type MFI, and subjecting the liquid feed stream to epoxidation reaction conditions in the epoxidation reactor, obtaining a reaction mixture comprising propylene oxide, methanol, water, and the at least one dissolved potassium salt of hydroxyethylidenediphosphonic acid, and optionally propane; removing an effluent stream from the epoxidation reactor, the effluent stream comprising propylene oxide, methanol, water, at least a portion of the at least one potassium salt of hydroxyethylidenediphosphonic acid, and optionally propane.

Provided herein are methods for producing ,-unsaturated ketones from the condensation of methyl ketones in the presence of an amine catalyst. Such amine catalysts may be supported, for example, on a silica-alumina support. Such amine catalysts may be used in the presence of an additional acid. The ,-unsaturated ketones may be produced by dimerization and/or timerization of the methyl ketones. Such ,-unsaturated ketones may be suitable for use in producing fuels, gasoline additives, and/or lubricants, or precursors thereof. The methyl ketones may be obtained from renewable sources, such as by the fermentation of biomass.

The present invention provides unimolecular metal complexes having increased activity in the copolymerization of carbon dioxide and epoxides. Also provided are methods of using such metal complexes in the synthesis of polymers. According to one aspect, the present invention provides metal complexes comprising an activating species with co-catalytic activity tethered to a multidentate ligand that is coordinated to the active metal center of the complex.

The compound of the formula (1) and its complexes with metal cations are used for catalysis in hydroformylation processes.

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