A method for preparing polycondensation products of guanidine, aminoguanidine or diaminoguanidine G with one or more benzyl or allyl derivatives BA according to the following reaction scheme is provided:

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wherein X, R.sub.1, Gua, Y and Z are as defined in the specification. In the disclosed method, at least one benzyl or allyl derivative BA is subjected to a polycondensation reaction with excessive guanidine, aminoguanidine or diaminoguanidine G upon elimination of HX.

The present invention relates to a new crystal modification of N-(aminoiminomethyl)-2-aminoacetic acid as well as a method for producing this crystal modification.

The present invention relates to a new crystal modification of N-(aminoiminomethyl)-2-aminoacetic acid as well as a method for producing this crystal modification.

Provided are an environmentally-friendly high-efficiency method of manufacturing an ester compound based on an esterification reaction using a salt ion-exchange method and an ester compound manufactured thereby. In the conventional esterification reaction, an ester was produced in low yields due to the hydrolysis (i.e., reverse reaction) caused by water, or it was required to continuously supply hydrochloric acid gas or use thionyl chloride, which is a hazardous material, and thus there were limitations in terms of environmental friendliness or cost. On the other hand, in the present invention, hydrochloric acid gas is continuously supplied using the salt ion-exchange method, and since magnesium sulfate acts as a dehydrating agent, the water generated in the esterification reaction is removed, and thus the occurrence of hydrolysis (i.e., reverse reaction) is suppressed and a conversion rate to the desired ester compound is increased. In addition, since the reactants are inexpensive and the product is less hazardous and easy to handle, a more efficient reaction is possible.

Provided are an environmentally-friendly high-efficiency method of manufacturing an ester compound based on an esterification reaction using a salt ion-exchange method and an ester compound manufactured thereby. In the conventional esterification reaction, an ester was produced in low yields due to the hydrolysis (i.e., reverse reaction) caused by water, or it was required to continuously supply hydrochloric acid gas or use thionyl chloride, which is a hazardous material, and thus there were limitations in terms of environmental friendliness or cost. On the other hand, in the present invention, hydrochloric acid gas is continuously supplied using the salt ion-exchange method, and since magnesium sulfate acts as a dehydrating agent, the water generated in the esterification reaction is removed, and thus the occurrence of hydrolysis (i.e., reverse reaction) is suppressed and a conversion rate to the desired ester compound is increased. In addition, since the reactants are inexpensive and the product is less hazardous and easy to handle, a more efficient reaction is possible.

Provided are an environmentally-friendly high-efficiency method of manufacturing an ester compound based on an esterification reaction using a salt ion-exchange method and an ester compound manufactured thereby. In the conventional esterification reaction, an ester was produced in low yields due to the hydrolysis (i.e., reverse reaction) caused by water, or it was required to continuously supply hydrochloric acid gas or use thionyl chloride, which is a hazardous material, and thus there were limitations in terms of environmental friendliness or cost. On the other hand, in the present invention, hydrochloric acid gas is continuously supplied using the salt ion-exchange method, and since magnesium sulfate acts as a dehydrating agent, the water generated in the esterification reaction is removed, and thus the occurrence of hydrolysis (i.e., reverse reaction) is suppressed and a conversion rate to the desired ester compound is increased. In addition, since the reactants are inexpensive and the product is less hazardous and easy to handle, a more efficient reaction is possible.

There is provided an α-carbonyl alkenyl ester and a preparation method therefor, and the α-carbonyl alkenyl ester is further used to react with a primary or secondary amine to prepare an amide. The two reactions are combined to develop an amide bond and peptide bond formation method that directly use carboxylic acids and amines as starting materials and allenones as a condensing reagent. The α-carbonyl alkenyl ester corresponding to an α-amino acid serves as a peptide synthesis building block and is used in solid phase peptide synthesis. The method is carried out under mild reaction conditions, simple to operate, and has a high yield. Compared with existing amide bond condensation reagents, the allenones have the advantages of being simple to prepare, having good stability, a low molecular weight, not racemizing when activating α-chiral carboxylic acids, and is a novel amide bond and peptide bond condensing reagent.

There is provided an α-carbonyl alkenyl ester and a preparation method therefor, and the α-carbonyl alkenyl ester is further used to react with a primary or secondary amine to prepare an amide. The two reactions are combined to develop an amide bond and peptide bond formation method that directly use carboxylic acids and amines as starting materials and allenones as a condensing reagent. The α-carbonyl alkenyl ester corresponding to an α-amino acid serves as a peptide synthesis building block and is used in solid phase peptide synthesis. The method is carried out under mild reaction conditions, simple to operate, and has a high yield. Compared with existing amide bond condensation reagents, the allenones have the advantages of being simple to prepare, having good stability, a low molecular weight, not racemizing when activating α-chiral carboxylic acids, and is a novel amide bond and peptide bond condensing reagent.

There is provided an α-carbonyl alkenyl ester and a preparation method therefor, and the α-carbonyl alkenyl ester is further used to react with a primary or secondary amine to prepare an amide. The two reactions are combined to develop an amide bond and peptide bond formation method that directly use carboxylic acids and amines as starting materials and allenones as a condensing reagent. The α-carbonyl alkenyl ester corresponding to an α-amino acid serves as a peptide synthesis building block and is used in solid phase peptide synthesis. The method is carried out under mild reaction conditions, simple to operate, and has a high yield. Compared with existing amide bond condensation reagents, the allenones have the advantages of being simple to prepare, having good stability, a low molecular weight, not racemizing when activating α-chiral carboxylic acids, and is a novel amide bond and peptide bond condensing reagent.

The present invention generally relates to novel synthetic methods, systems, kits, salts, and precursors useful in medical imaging. In some embodiments, the present invention provides compositions comprising an imaging agent precursor, which may be formed using the synthetic methods described herein. An imaging agent may be converted to an imaging agent using the methods described herein. In some cases, the imaging agent is enriched in .sup.18F. In some cases, an imaging agent including salt forms (e.g., ascorbate salt) may be used to image an area of interest in a subject, including, but not limited to, the heart, cardiovascular system, cardiac vessels, brain, and other organs.