Method of verifying the synthesis of organic molecules using nuclear magnetic resonance spectroscopy

Abstract

A NMR method to verify the presence of organic molecular compounds consisting of repetitive occurring substructures is presented. The method comprises the steps of assigning sub-structure codes to the selected compounds, in accordance with the respective starting compounds used, measuring multi-dimensional NMR spectra from at least some of the compounds, uniquely assigning signal groups of NMR spectra to the individual sub-structures, checking the NMR spectra of the compounds for the presence of all assigned signal groups, and characterizing a particular compound as being TRUE if the check of its particular combination of substructures yields the result that the signal groups of substructures contained in its total code had been observed. The method permits rapid and accurate verification of the presence of compounds having repetitive substructures.

We claim:  
     
         1 . A nuclear magnetic resonance (NMR) method to verify the presence of compounds from a library of organic molecular compounds, the compounds consisting of molecular sub-structures, the method comprising the following steps: 
 (A) selecting at least two classes of molecular sub-structures, each class having a plurality of sub-structure species;    (B) assigning a sub-structure code to each species, said code comprising a sub-structure class and a sub-structure index;    (C) selecting compounds containing these species;    (D) measuring multi-dimensional NMR spectra of at least a subset of the selected organic molecular compounds in the library;    (E) uniquely assigning signal groups in said NMR spectra to individual sub-structures and individual sub-structure codes;    (F) checking said NMR spectra for the presence of all assigned signal groups;    (G) if said checking of a particular spectrum indicates that the signal groups of sub-structures contained in one compound had been observed, this particular compound is characterized to be TRUE.    
     
     
         2 . The method of  claim 1 , comprising the additional step: 
 (H) if the check of a particular compound yields the result that at least one of the signal groups of the sub-structures contained in a total code of that compound had not been observed, this particular combination is characterized to be FALSE.    
     
     
         3 . The method of  claim 2 , comprising the additional steps of examining, prior to steps (G) and (H), the NMR spectra for at least one of a signal to noise ratio and a core signal intensity and characterizing a combination of sub-structures as VAGUE if at least one of said signal to noise ratio and said core signal intensity is less than a threshold value.  
     
     
         4 . The method of  claim 1 , wherein the steps (E) and (F) comprise: 
 (E 1 ′) selecting of subset of compounds, wherein each sub-structure is present in at least one of the compounds in the subset;    (E 2 ′) uniquely assigning signal groups of the NMR spectra of said subset to individual sub-structures;    (E 3 ′) if it is not possible to uniquely assign one signal group to each sub-structure, selection of a modified subset is performed and the process repeated starting from step (E 2 ′) ; and    (F′) checking NMR spectra of remaining compounds, that do not belong to said subset, for presence of all assigned signal groups.    
     
     
         5 . The method of  claim 2 , wherein the steps (E) and (F) comprise: 
 (E 1 ′) selecting a subset of compounds, wherein each sub-structure is present in at least one compound;    (E 2 ′) uniquely assigning signal groups of the NMR spectra of said subset to individual sub-structures;    (E 3 ′) if it is not possible to uniquely assign one signal group to each sub-structure, a selection of a modified subset of compounds is performed and the process repeated starting from step (E 2 ′);    (F′) checking NMR spectra of remaining compounds, that do not belong to said subset, for a presence of all assigned signal groups.    
     
     
         6 . The method of  claim 3 , wherein the steps (E) and (F) comprise in detail: 
 (E 1 ′) selecting a subset of compounds, wherein each sub-structure is present in at least one compound;    (E 2 ′) uniquely assigning signal groups of NMR spectra of said subset to individual sub-structures;    (E 3 ′) if it is not possible to uniquely assign one signal group to each sub-structure, a modified subset is selected and the procedure repeated starting from step (E 2 ′);    (F′) checking NMR spectra of remaining compounds, that do not belong to said subset, for the presence of all assigned signal groups.    
     
     
         7 . The method of  claim 4 , wherein said subset of step (E 1 ′) is derived by modifying a subset of compounds of an earlier measuring series.  
     
     
         8 . The method of  claim 5 , wherein said subset of step (E 1 ′) is derived by modifying a subset of compounds of an earlier measuring series.  
     
     
         9 . The method of  claim 6 , wherein said subset of step (E 1 ′) is derived by modifying a subset of compounds of an earlier measuring series.  
     
     
         10 . The method of  claim 4 , wherein a number of compounds contained in said subset is minimized.  
     
     
         11 . The method of  claim 5 , wherein a number of compounds contained in said subset is minimized.  
     
     
         12 . The method of  claim 9 , wherein a number of compounds contained in said subset is minimized.  
     
     
         13 . The method of  claim 1 , wherein the organic molecular compounds have molecular weights in a range from 100 u to 2000 u.  
     
     
         14 . The method of  claim 3 , wherein the organic molecules have molecular weights in the range from 100 u to 2000 u.  
     
     
         15 . The method of  claim 1 , wherein a common core is present in all compounds.  
     
     
         16 . The method of  claim 3 , wherein a common core is present in all compounds.  
     
     
         17 . The method of  claim 15 , wherein said core is a sub-structure with between 2 and 6 binding sites.  
     
     
         18 . The method of  claim 1 , wherein a number of sub-structures is between 5 and 500.  
     
     
         19 . The method of  claim 1 , wherein said multi-dimensional NMR spectrum is a two-dimensional  1 H and  13 C correlated spectrum.  
     
     
         20 . The method of  claim 1 , wherein said assignment of signal groups in the NMR spectra to individual sub-structures is achieved by formal addition and subtraction of normalized structure codes.  
     
     
         21 . The method of  claim 3 , further comprising generating peak lists of multi-dimensional NMR spectra for definition of signal groups.  
     
     
         22 . The method of  claim 21 , wherein a data point of a multi-dimensional NMR spectrum is recognized to be a peak if its intensity is larger than that of n neighboring data points, wherein 4≦n≦12.  
     
     
         23 . The method of  claim 22 , wherein neighboring peaks are combined into clusters and are analyzed by means of cluster analysis, wherein one or more clusters are assigned to the sub-structures as signal groups.  
     
     
         24 . The method of  claim 23 , wherein a cluster area is assigned to each cluster inside a two-dimensional NMR spectrum and wherein a particular sub-structure is recognized to be identified if an NMR signal, integrated over said cluster area, is greater than a predetermined limit for all cluster areas assigned to said particular sub-structure.  
     
     
         25 . The method of  claim 24 , wherein said limit is a ratio to an integral of NMR signal over cluster areas which are assigned to other sub-structures.  
     
     
         26 . The method of  claim 3 , wherein, in steps (G) to (I), a table is created containing symbols indicating, for all sub-structures (columns), whether they were identified (+) in the NMR spectra or not (−), and wherein, in three additional columns, a sum of the identified sub-structures, a total classification (TRUE, FALSE, VAGUE), and a required total code are displayed.  
     
     
         27 . The method of  claim 25 , wherein, in steps (G) to (I), a table is created containing symbols indicating, for all sub-structures (columns), whether they were identified (+) in the NMR spectra or not (−), and wherein, in three additional columns, a sum of the identified sub-structures, a total classification (TRUE, FALSE, VAGUE), and a required total code are displayed.  
     
     
         28 . A nuclear magnetic resonance method to verify the presence of organic molecular compounds in a library of compounds having molecular weights in a range from 100 U to 2000 U and having between 5 and 500 sub-structures of interest, the method comprising the following steps: 
 (A) selecting at least two classes of molecular sub-structures, each class comprising a plurality of sub-structure species;    (B) assigning a sub-structure class and a sub-structure code to each species;    (C) selecting organic molecular compounds of the library containing the sub-structures, wherein a total code is assigned to each compound in the library;    (D) measuring n-dimensional (1≦n≦3) NMR spectra, comprising at least one of  1 H and  13 C, of at least some of the selected organic molecular compounds in the library;    (E1′) selecting a subset of compounds, wherein each sub-structure is present in at least one compound in said subset, wherein a number of compounds contained in said subset is minimized;    (E2′) uniquely assigning signal groups of the NMR spectra to individual sub-structures by formal addition and subtraction on respective structure codes;    (E3′) if it is not possible to uniquely assign one signal group to each sub-structure, a modified subset of compounds is selected and the process repeated starting from step (E2′);    (F′) checking the NMR spectra of remaining compounds, that do not belong to said subset, for a presence of all assigned signal groups;    (G) if said checking of a particular compound indicates that exactly signal groups of sub-structures contained in said compound had been observed, this particular compound is characterized to be TRUE;    (H) if said checking of a particular compound indicates that at least one of signal groups of sub-structures contained in that compound had not been observed, this particular compound is characterized to be FALSE;    (I) if said checking of a particular compound indicates that neither (G) nor (H) is the case, this particular compound is characterized to be VAGUE;    
     
     
         29 . The method of  claim 28 , further comprising constructing peak lists of multi-dimensional NMR spectra for definition of signal groups.  
     
     
         30 . The method of  claim 29 , wherein a data point of an n-dimensional NMR spectrum is recognized to be a peak if its intensity is larger than that of n neighboring data points, with 4≦n≦12.  
     
     
         31 . The method of  claim 30 , wherein neighboring peaks are combined into clusters and are analyzed by means of cluster analysis, wherein one or more clusters are assigned to sub-structures as signal groups.  
     
     
         32 . The method of  claim 31 , wherein a cluster range is assigned to each cluster inside an n-dimensional NMR spectrum and wherein a particular sub-structure is recognized to be identified if an NMR signal, integrated over a cluster range, is greater than a predetermined limit for all cluster ranges assigned to that particular sub-structure.  
     
     
         33 . The method of  claim 32 , wherein said limit is a ratio to an integral of NMR signal over cluster ranges which are assigned to other sub-structures.  
     
     
         34 . The method of  claim 33 , wherein, in steps (G) to (I), a table is created containing symbols indicating, for all sub-structures (columns), whether they were identified (+) in the NMR spectra compounds not present in said subset or not (−), and wherein, in three additional columns, a sum of identified sub-structures, a total classification (TRUE, FALSE, VAGUE), and an associated total code are displayed.