Patent Description:
One-pot synthesis is understood as a strategy in which the synthesis initiating substrate (initiator) is subjected to subsequent chemical reactions in a controlled manner, in one reactor, without intermediate products being isolated between individual reactions. In other words, it is multi-stage synthesis performed in one pot, without purifying the products in its various steps.

The currently used methods of oligo- and polycarbamate synthesis are methods of stepwise polymerisation (see, for example: <NPL> and <NPL>), but these methods make it impossible to control the monomeric sequence. The oligo- and polycarbamates obtained by polymerisation are characterised by a heterogeneous structure and distribution of molar masses. The only method known so far for synthesizing homogeneous oligo- and polycarbamates with a controlled monomeric sequence is iterative synthesis on a support or in a solution. In the method on a support, synthesis is performed on a hydroxy-functionalised support with two reactions being employed: (i) activation of the alcohol group with N,N'-disuccinimidyl carbonate, and (ii) a chemoselective aminoalcohol coupling reaction resulting in a carbamate bond. On the other hand, all methods of synthesis of oligo- and polycarbamates in a solution described so far require purification between their steps.

The invention described in application <CIT> relates to polyurethanes with a particular sequence and methods for their preparation. Said application discloses novel synthetic polyurethanes having different functional groups with unique, defined structures, as well as a method for preparing these uniform polyurethanes with a specific sequence. In general, according to the invention described therein, the synthesis of polyurethanes comprises (i) dissolving N,N'-disuccinimidyl carbonate in dry acetonitrile and adding triethylamine to the solution, the reaction takes place at <NUM>, then transferring to a solid phase extraction tube and rinsing with N,N-dimethylformamide, and step (ii) of coupling which comprises adding a solution of triethylamine and aminoalcohol in dry N,N-dimethylformamide to an extraction tube containing a solid support activated with N,N'-disuccinimidyl carbonate. Steps (i) and (ii) are repeated an appropriate number of times to obtain an oligocarbamate chain of a desired length. In each step (ii), the molecular structure of the block which builds the aminoalcohol may be different to synthesise oligomers with a controlled sequence.

A similar method employing a solid support is described in <NPL>. These methods, however, are based on synthesis on a solid support which has a number of constraints: (<NUM>) small scale of synthesis, (<NUM>) the need to use an excess of reagents, (<NUM>) high costs of a support, (<NUM>) the inability to monitor synthesis by traditional chromatographic methods, (<NUM>) the need to use a large excess of solvents to purify the product after each step. These constraints do not allow oligo- and polycarbamates to be obtained on an industrial scale, which makes it impossible to use these syntheses in industry.

All described methods of synthesis in a solution require purification between steps (<NPL>; <NPL>). The necessity for purification after each step using chromatography makes synthesis very complicated, increases the time and cost of synthesis, requires the use of an additional portion of solvents and materials needed to isolate products and generates efficiency losses. Recently, a scalable method of synthesizing oligocarbamate-based gels with a controlled monomeric sequence has been described in the literature. The synthesis is performed in a solution using vanillin carbonate as an activator (<NPL>). However, this method makes it possible to control the monomeric sequence of the obtained macromolecules only within the side group of nitrogen substituents. The method involves purification by extraction after each step.

The aim of the invention was to develop a method for the synthesis of oligocarbamates with a defined monomeric sequence that would overcome the said disadvantages of the methods known from the prior art, i.e. difficult scalability, the necessity for purification after each step, a complicated synthesis protocol, the necessity to use a support, high costs of synthesis and high consumption of solvents and reagents.

The subject matter of the invention is a method for the preparation of oligocarbamates with a defined monomeric sequence of the general formula
<CHM>
characterised in that the multistage synthesis is performed in one reaction pot without the necessity for purification between successive reactions, and the synthesis is driven by the addition of fresh portions of the N,N'-disuccinimidyl carbonate activator or a monomer in the form of HO-R<NUM>-NH<NUM> aminoalcohol, after complete conversion of the previous step has been confirmed, the method comprising the following steps:.

Preferably, R<NUM>-OH alcohol is selected from the group comprising benzyl alcohol, <NUM>-[(Boc-aminomethyl)phenyl]methanol and <NUM>-Boc-amino-<NUM>-phenylol-<NUM>-propanol.

Preferably, HO-R <NUM>-NH<NUM> aminoalcohol is selected from the group comprising <NUM>-amino-<NUM>-propanol, (S)-(+)-<NUM>-amino-<NUM>-propanol, (R)-(+)-<NUM>-amino-<NUM>-propanol, (S)-<NUM>-amino-<NUM>-propanol, (R)-<NUM>-amino-<NUM>-propanol and <NUM>-(aminomethyl)phenylmethanol.

Preferably, the reactions in steps (i. ) are performed under inert atmosphere. More preferably, the inert atmosphere is nitrogen or argon atmosphere.

The method for the preparation of oligocarbamates with a defined monomeric sequence according to the invention is shown in <FIG>. The method makes it possible to obtain homogeneous oligocarbamates with a defined monomeric sequence of the general formula shown in Scheme <NUM> A,
<CHM>
<CHM>.

Scheme <NUM>. The reactions employed to prepare oligocarbamates with a defined monomeric sequence according to the developed invention.

Preferably, R<NUM> is an aromatic substituent having no nucleophilic substituents and reactive functional groups in its structure, an aromatic substituent with a Boc-protected amino group, with, e.g., benzyl alcohol, <NUM>-[(Boc-aminomethyl)phenyl]methanol and <NUM>-Boc-amino-<NUM>-phenylol-<NUM>-propanol possible to be used as the initiator.

Preferably, R<NUM> is an alkyl of a various structure, e.g. a linear structure (-CH<NUM>-CH<NUM>-CH<NUM>-), a non-linear structure (-CH<NUM>-CH(CH<NUM>)- or an alkyl having at least one aryl (-CH<NUM>-C<NUM>H<NUM>-CH<NUM>-).

Preferably, the aminoalcohol is selected from the group comprising the aminoalcohols shown in Table <NUM>, including <NUM>-aminopropan-<NUM>-ol, (S)-(+)-<NUM>-aminopropan-<NUM>-ol, (R)-<NUM>-aminopropan-<NUM>-ol, m-(aminomethyl)benzyl alcohol.

Additionally, preferably, the reagents in steps (i. ) are used in amounts of from equimolar to double molar excess with respect to the amount of the initiator used.

Preferably, the reactions in steps (i. ) are performed under inert atmosphere. More preferably, the inert atmosphere is nitrogen or argon atmosphere.

Furthermore, preferably, the N-hydroxysuccinimide by-product is removed after synthesis by washing with water.

Preferably, the reactions in steps (i. ) are performed in the presence of pyridine.

Preferably, the reactions in steps (i. ) are performed at room temperature.

The developed method of one-pot synthesis begins with the reaction of i. activation of an alcohol with an active carbonate, followed by a chemoselective reaction of the resulting product with the amino group of aminoalcohol ii. (in particular aminoalcohols with primary and secondary amine/alcohol). The free hydroxyl group of the resulting product is activated by the addition of a fresh portion of the activator. After complete conversion of the hydroxyl group to carbonate, synthesis is continued by the addition of a portion of another monomer. The two reactions ii. are repeated cyclically until the desired oligomer sequence is obtained. Importantly, the monomer/activator is added after complete conversion of the previous step is confirmed. Whether the conversion of the activator/monomer is complete can be verified, e.g., by HPLC chromatography with a reversed-phase C18 column. Each addition of another portion of monomer makes it possible to control the order of monomers in the chain. The steps of activation and chemoselective coupling of alcohol are repeated until an oligomer of a desired monomeric sequence is obtained. The reactions are performed in one reaction pot and the course of subsequent steps is driven by the addition of a new portion of activator/monomer reagents. Each step of aminoalcohol activation/coupling generates the N-hydroxysuccinimide by-product, which is removed after synthesis by washing with water. In the disclosed method, it is critical to perform alcohol activation and coupling reactions until complete conversion. When calculating the amounts of reagents, the purity of the reagents used and the conversion of substrates should be taken into account. Depending on the monomers used and the target oligomer sequence, some reactions require the use of excesses of reagents. The excesses needed are calculated based on the amount of the unreacted substrates based on the chromatographic analysis, which means that a suitable amount of moles is added necessary for complete conversion. High purity (e.g. dry) solvents should be used for synthesis and, if possible, the reaction should be performed under inert atmosphere (e.g. nitrogen or argon atmosphere).

A distinctive feature of the proposed method of oligocarbamate synthesis according to the invention is that the synthesis is conducted in one pot and no purification is needed, e.g., no extraction or precipitation after each step of synthesis, no support that would limit the scale of synthesis or require the use of a large excess of reagents/solvents. The main element of the method for preparation of oligocarbamates (oligourethanes) with a specific sequence is a one-pot synthesis driven by successive portions of (activator/monomer) reagents. The developed method of synthesis has many advantages over the methods currently used: (<NUM>) it is scalable (Example O2-O2', O6-O6'), (<NUM>) it limits the use of organic solvents, (<NUM>) it does not require the use of a large excess of reagents, (<NUM>) it does not require purification after each synthesis step and (<NUM>) it does not require the use of a support. Given points (<NUM>), (<NUM>), (<NUM>) and (<NUM>), the developed method will significantly reduce the cost of synthesis compared to the methods currently used. The oligocarbamates obtained by the method are characterised by a defined chemical structure, i.e. a defined sequence of monomers in the chain, defined end groups, which can be subjected to further modifications, and no molar mass dispersions or, in other words, a homogeneous structure (Examples <NUM>-<NUM>).

The developed method consists in a reaction sequence of activation and chemoselective coupling of aminoalcohol monomers in one reaction pot, according to the scheme shown in <FIG>. The distinctive features and undoubted advantages of the method of the present invention are also:.

The subject matter of the invention is shown in the attached drawing, in which:.

Initiation (Scheme <NUM>, B i. ): Alcohol (<NUM> equiv. ) was dissolved in dry acetonitrile (<NUM>-<NUM> solution). Dry pyridine (Pyr, <NUM>-<NUM> equiv. ) and anisole standard (<NUM> mol% relative to alcohol) were then added to the solution, and then the N,N'-disuccinimidyl carbonate activator (DSC, <NUM> equiv. ) was added to the mixture. The reaction was performed at room temperature until complete activation of alcohol.

Propagation (Scheme <NUM>, B ii. ): To the activated alcohol (<NUM> equiv. ) was added a portion of the first monomer: (<NUM> equiv. The reaction was performed until complete conversion of the activated alcohol. Then another portion of the N,N'-disuccinimidyl carbonate activator (DSC, <NUM> equiv. ) was added to activate the hydroxyl group of the growing macromolecule. After complete activation of the hydroxyl group, the coupling reaction of another monomer (<NUM> equiv. ) was performed. According to the above protocol, successive reactions of hydroxyl group activation by adding DSC activator (DSC, <NUM> equiv. ) and monomer coupling were repeated until the desired oligomer sequence was obtained. All reactions were performed at room temperature and under nitrogen atmosphere and their progress was controlled by HPLC chromatography. In the disclosed method, it is critical to perform alcohol activation and monomer coupling reactions until complete conversion of substrates. Note: High purity (e.g. dry) solvents were used for synthesis and the reactions were performed under inert atmosphere (e.g. nitrogen or argon atmosphere). Depending on the monomers used and the target oligomer sequence, some reactions require the use of excesses of reagents. The excesses needed are calculated based on the amount of the unreacted substrates determined using chromatography, which means that a suitable amount of moles is added necessary for complete conversion. This amount is set experimentally for each sequence based on synthesis monitoring. The table below provides the exact amounts of reagents used and the excesses of reagents used during <NUM>-<NUM> syntheses.

After completion of synthesis, the solvent was evaporated under reduced pressure (<NUM>). The product was dissolved in ethyl acetate and extracted with an aqueous NaCl solution to remove the resulting N-hydroxysuccinimide by-product. The organic phase containing the product was dried with anhydrous Na<NUM>SO<NUM> and filtered. The solvent was then evaporated and the product was dried under reduced pressure (<NUM>).

Claim 1:
Method for the preparation of oligocarbamates with a defined monomeric sequence of a general formula
<CHM>
characterised in that the multistage synthesis is performed in one reaction pot without the necessity for purification between successive reactions, and the synthesis is driven by the addition of fresh portions of the N,N'-disuccinimidyl carbonate activator or a monomer in the form of HO-R<NUM>-NH<NUM> aminoalcohol, after complete conversion of the previous step has been confirmed, the method comprising the following steps:
i. initiation which comprises the activation of <NUM> equiv. of alcohol dissolved in dry acetonitrile - a solution of <NUM>-<NUM> with <NUM>-<NUM> equiv. of dry pyridine added - by the addition of an activator, being <NUM>-<NUM> equiv. of N,N'-disuccinimidyl carbonate, to the mixture and performing the reaction at room temperature until complete activation of alcohol, wherein the R<NUM>-OH alcohol is an aromatic primary or secondary alcohol not containing free nucleophilic groups in its structure;
ii. at least one propagation of the oligomer chain by the addition of a portion of <NUM>-<NUM> equiv. of the first monomer in the form of HO-R<NUM>-NH<NUM> aminoalcohol to <NUM> equiv. of the activated alcohol of step (i.) and performing the reaction until complete conversion of the activated alcohol, and then the addition of a further portion of the activator, being <NUM>-<NUM> equiv. of N,N'-disuccinimidyl carbonate, to activate the hydroxyl group of the growing macromolecule, wherein the substituent R<NUM> is selected from the group comprising a linear or branched C3-C8 alkyl and a C3-C8 alkyl having at least one aryl, composed of <NUM>-<NUM> carbon atoms and not containing free nucleophilic groups in its structure;
iii. repeating the propagation step until the desired oligocarbamate sequence is achieved.