Isoselective polymerization of epoxides

Abstract

The present invention provides novel bimetallic complexes and methods of using the same in the isoselective polymerization of epoxides. The invention also provides methods of kinetic resolution of epoxides. The invention further provides polyethers with high enantiomeric excess that are useful in applications ranging from consumer goods to materials.

What is claimed is: 
     
         1 . A bimetallic complex of formula I: 
       
         
           
           
               
               
           
         
       
       wherein:
 M is a metal atom; 
 X is a nucleophile; 
 n is an integer from 0 to 2, inclusive 
 each occurrence of L 1 , L 2 , Y 1 , and Y 2  is independently —O—, P(R′) 2 , ═NR′—, or —N(R′) 2 —; 
 each occurrence of 
 
       
         
           
           
               
               
           
         
       
       is an optionally substituted moiety selected from the group consisting of C 2-12  aliphatic, C 7-12  arylalkyl; 6-10-membered aryl; 5-10-membered heteroaryl having 1-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur; and 4-7-membered heterocyclic having 1-2 heteroatoms independently selected from the group consisting of nitrogen, oxygen, and sulfur;
 each occurrence of 
 
       
         
           
           
               
               
           
         
       
       is an optionally substituted moiety selected from the group consisting of C 7-12  arylalkyl; 6-10-membered aryl; and 5-10-membered heteroaryl having 1-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur;
    represents a single bond directly attached to an aryl or heteroaryl ring of each 
 
       
         
           
           
               
               
           
         
         each occurrence of R′ is hydrogen or an optionally substituted moiety selected from the group consisting of a C 3 -C 14  carbocycle, a C 6 -C 10  aryl group, a C 3 -C 14  heterocycle, and a C 5 -C 10  heteroaryl group; or an optionally substituted C 2-20  aliphatic group, wherein one or more methylene units are optionally and independently replaced by —NR y —, —N(R y )C(O)—, —C(O)N(R y )—, —OC(O)N(R y )—, —N(R y )C(O)O—, —OC(O)O—, —O—, —C(O)—, —OC(O)—, —C(O)O—, —S—, —SO—, —SO 2 —, —C(═S)—, —C(═NR y )—, —C(═NOR y )— or —N═N—; or 
         two R′ are taken together with their intervening atoms to form a monocyclic or bicyclic 5-12-membered ring; 
         wherein a substituent may comprise one or more organic cations; and 
         each occurrence of R y  is independently hydrogen or an optionally substituted C 1-6  aliphatic group. 
       
     
     
         2 . The bimetallic complex of  claim 1 , wherein M is a main group metal. 
     
     
         3 . The bimetallic complex of  claim 1 , wherein M is selected from the group consisting of a transition metal from group 5-12, inclusive, boron and aluminum. 
     
     
         4 . A polymer of formula: 
       
         
           
           
               
               
           
         
       
       wherein:
 R a  is an optionally substituted group selected from the group consisting of C 1-12  aliphatic; 
 C 1-12  heteroaliphatic having 1-4 heteroatoms independently selected from the group consisting of nitrogen, oxygen, and sulfur; 6-10-membered aryl; 5-10-membered heteroaryl having 1-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur; and 4-7-membered heterocyclic having 1-2 heteroatoms independently selected from the group consisting of nitrogen, oxygen, and sulfur; and 
 each of R b  and R c  is independently hydrogen or an optionally substituted group selected from the group consisting of C 1-12  aliphatic; C 1-12  heteroaliphatic having 1-4 heteroatoms independently selected from the group consisting of nitrogen, oxygen, and sulfur; 6-10-membered aryl; 5-10-membered heteroaryl having 1-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur; and 4-7-membered heterocyclic having 1-2 heteroatoms independently selected from the group consisting of nitrogen, oxygen, and sulfur; 
 wherein any of (R a  and R c ), (R b  and R c ), and (R a  and R b ) can be taken together with their intervening atoms to form one or more rings selected from the group consisting of: optionally substituted C 3 -C 14  carbocycle, optionally substituted C 3 -C 14  heterocycle, optionally substituted C 6 -C 10  aryl, and optionally substituted C 5 -C 10  heteroaryl; 
 wherein the enantiomeric excess of the polymer is greater than 90%. 
 
     
     
         5 . The polymer of  claim 4 , wherein the polymer comprises a copolymer of two different repeating units where R a , R b , and R c  of the two different repeating units are not all the same. 
     
     
         6 . The polymer of  claim 4 , wherein the polymer comprises a copolymer of three or more different repeating units wherein R a , R b , and R c  of each of the different repeating units are not all the same as R a , R b , and R c  of any of the other different repeating units. 
     
     
         7 . A polymer of formula: 
       
         
           
           
               
               
           
         
       
       wherein:
 R a  is an optionally substituted group selected from the group consisting of C 1-12  aliphatic; C 1-12  heteroaliphatic having 1-4 heteroatoms independently selected from the group consisting of nitrogen, oxygen, and sulfur; 6-10-membered aryl; 5-10-membered heteroaryl having 1-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur; and 4-7-membered heterocyclic having 1-2 heteroatoms independently selected from the group consisting of nitrogen, oxygen, and sulfur; and 
 each of R b  and R c  is independently hydrogen or an optionally substituted group selected from the group consisting of C 1-12  aliphatic; C 1-12  heteroaliphatic having 1-4 heteroatoms independently selected from the group consisting of nitrogen, oxygen, and sulfur; 6-10-membered aryl; 5-10-membered heteroaryl having 1-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur; and 4-7-membered heterocyclic having 1-2 heteroatoms independently selected from the group consisting of nitrogen, oxygen, and sulfur; 
 wherein any of (R a  and R c ), (R b  and R c ), and (R a  and R b ) can be taken together with their intervening atoms to form one or more rings selected from the group consisting of: optionally substituted C 3 -C 14  carbocycle, optionally substituted C 3 -C 14  heterocycle, optionally substituted C 6 -C 10  aryl, and optionally substituted C 5 -C 10  heteroaryl; 
 wherein the isotacticity of the polymer is greater than 90%. 
 
     
     
         8 . A method of polymerization, the method comprising:
 a) providing a prochiral epoxide of formula:   
       
         
           
           
               
               
           
         
       
       wherein:
 R a  is an optionally substituted group selected from the group consisting of C 1-12  aliphatic; C 1-12  heteroaliphatic having 1-4 heteroatoms independently selected from the group consisting of nitrogen, oxygen, and sulfur; 6-10-membered aryl; 5-10-membered heteroaryl having 1-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur; and 4-7-membered heterocyclic having 1-2 heteroatoms independently selected from the group consisting of nitrogen, oxygen, and sulfur; and 
 each of R b  and R c  is independently hydrogen or an optionally substituted group selected from the group consisting of C 1-12  aliphatic; C 1-12  heteroaliphatic having 1-4 heteroatoms independently selected from the group consisting of nitrogen, oxygen, and sulfur; 6-10-membered aryl; 5-10-membered heteroaryl having 1-4 heteroatoms independently selected from nitrogen, oxygen, or sulfur; and 4-7-membered heterocyclic having 1-2 heteroatoms independently selected from the group consisting of nitrogen, oxygen, and sulfur; 
 wherein any of (R a  and R c ), (R b  and R c ), and (R a  and R b ) can be taken together with their intervening atoms to form one or more rings selected from the group consisting of: optionally substituted C 3 -C 14  carbocycle, optionally substituted C 3 -C 14  heterocycle, optionally substituted C 6 -C 10  aryl, and optionally substituted C 5 -C 10  heteroaryl; 
 
       and
 b) treating the epoxide with a bimetallic catalyst under suitable conditions to form a polymer of formula: 
 
       
         
           
           
               
               
           
         
       
     
     
         9 . The method of  claim 8 , wherein the bimetallic catalyst is a bimetallic complex of any one of  claims 1  to  46 . 
     
     
         10 . The method of  claim 8 , further comprising a step, after step (a), of adding at least one additional epoxide having the formula 
       
         
           
           
               
               
           
         
       
       wherein each of the additional epoxide has a structure different from the structure of the epoxide provided in step (a) such that the polymer formed in step (b) is a co-polymer of two or more epoxides.