Substituted imidazolium sulfuranes and their use
The present invention refers to substituted imidazolium sulfuranes, the use thereof for the transfer of a —CN group or an alkyne group.
1. An imidazolium sulfurane of the formula (I):
wherein:
R 1 and R 2 each independently represent hydrogen, alkyl, aralkyl, aryl, heteroaryl, each being optionally substituted by one or more hetero atoms selected from O, N, S or halogen, or R 1 and R 2 may together form a hydrocarbon ring structure, optionally substituted by one or more hetero atoms selected from O, N, S and halogen;
R 3 and R 4 each independently represent a lower alkyl group having 1 to 6 carbon atoms, each lower alkyl group being optionally substituted by one or more hetero atoms selected from O, N, S or halogen;
X is an anion selected from halogen or a non- or weak-coordinating anion;
Y represents a group of the —C≡W formula wherein W represents N, CR 5 ,
or C—CO 2 R 5 wherein R 5 is selected from the group consisting of C 1 to C 20 straight chain, branched chain or cyclic aliphatic hydrocarbons, optionally having one or more unsaturated bonds or C 6 to C 20 aromatic hydrocarbons and partially arene-hydrogenated hydrocarbons, each hydrocarbon optionally being substituted by one or more hetero atoms selected from O, N, S, halogen or a silylgroup;
with the proviso that compounds of the formula (I) wherein R 1 and R 2 are hydrogen, R 3 and R 4 are methyl, X is halogen and Y is CN are excluded.
2. The imidazolium sulfurane of the formula (I) as claimed in claim 1 wherein:
R 1 and R 2 each independently represent hydrogen or lower alkyl having 1 to 6 carbon atoms, optionally substituted by one or more hetero atoms selected from O, N, S or halogen, or R 1 and R 2 may together form a 5 to 7 membered hydrocarbon ring structure, optionally substituted by one or more hetero atoms selected from O, N, S or halogen;
R 3 and R 4 each independently represent a lower alkyl group having 1 to 6 carbon atoms, each lower alkyl group being optionally substituted by one or more hetero atoms selected from O, N, S or halogen;
X is an anion selected from halogen or a non- or weak-coordinating anion;
Y represents a group of the formula —C≡W wherein W represents N, CR 5 or C—CO 2 R 5 wherein R 5 is selected from the group consisting of C 1 to C 20 straight chain, branched chain or cyclic aliphatic hydrocarbons, C 3 -C 8 -heterocycloalkyl or C 6 to C 20 aromatic hydrocarbons and partially arene-hydrogenated forms, each hydrocarbon optionally being substituted by one or more hetero atoms selected from O, N, S, halogen or a tri-lower alkyl-silygroup.
3. The imidazolium sulfurane of the formula (I) as claimed in claim 1 , wherein:
R 1 and R 2 each independently represent hydrogen or lower alkyl having 1 to 6 carbon atoms, optionally substituted by one or more oxygen atoms, or R 1 and R 2 may together form a 5 to 7 membered hydrocarbon ring structure, optionally substituted by one or more oxygen or nitrogen atoms;
R 3 and R 4 each independently represent a lower alkyl group selected from methyl, ethyl, propyl, iso-propyl;
X is an anion selected from halogen or a non- or weak-coordinating anion;
Y represents a group of the —C≡W formula wherein W represents N, CR 5 or C—CO 2 R 5 wherein R 5 is selected from the group consisting of C 1 to C 20 straight chain, branched chain or cyclic aliphatic hydrocarbons, optionally having one or more unsaturated bonds or C 6 to C 20 aromatic hydrocarbons and partially arene-hydrogenated forms, each hydrocarbon optionally being substituted by one or more hetero atoms selected from O, N, S or halogen a tri-lower alkyl-silygroup.
4. The imidazolium sulfurane of the formula (I) as claimed in claim 1 , wherein:
R 1 and R 2 , R 3 and R 4 and X have the meaning as given in claim 1 and
Y represents a group of the formula:
wherein R 5 may be the same or different and may be selected from the group consisting of C 1 to C 20 straight chain, branched chain or cyclic aliphatic hydrocarbons, optionally having one or more unsaturated bonds or C 6 to C 20 aromatic hydrocarbons and partially arene-hydrogenated hydrocarbons, each hydrocarbon optionally being substituted by one or more hetero atoms selected from O, N, S or halogen a tri-lower alkyl-silygroup.
5. Process for preparing an imidazolium sulfurane compound of the formula (I):
wherein R 1 and R 2 , R 3 and R 4 , X and Y have the meanings as given in claim 1 ,
said process comprising reacting a compound of the formula (II):
wherein R 1 to R 4 have the meaning as given in claim 1 , in a first step, with a halogen to yield a resulting compound, and the resulting compound is reacted in a second step with a compound of the formula R—C≡W, wherein R is a lower alkyl silyl group, wherein the lower alkyl has 1 to 6 carbon atoms.
6. Process comprising reacting a compound of the formula (I):
wherein
R 1 and R 2 each independently represent hydrogen, alkyl, aralkyl, aryl, heteroaryl, each being optionally substituted by one or more hetero atoms selected from O, N, S or halogen, or R 1 and R 2 may together form a hydrocarbon ring structure, optionally substituted by one or more hetero atoms selected from O, N, S and halogen;
R 3 and R 4 each independently represent a lower alkyl group having 1 to 6 carbon atoms, each lower alkyl group being optionally substituted by one or more hetero atoms selected from O, N, S or halogen;
X is an anion selected from halogen or a non- or weak-coordinating anion;
Y represents a group of the —C≡W formula wherein W represents N, CR 5 ,
or C—CO 2 R 5 wherein R 5 is selected from the group consisting of C 1 to C 20 straight chain, branched chain or cyclic aliphatic hydrocarbons, optionally having one or more unsaturated bonds or C 6 to C 20 aromatic hydrocarbons and partially arene-hydrogenated hydrocarbons, each hydrocarbon optionally being substituted by one or more hetero atoms selected from O, N, S, halogen or a silylgroup;
with an organic nucleophilic compound R N —H wherein R N is alkyl, aralkyl, aryl or heteroaryl, each being optionally substituted by one or more hetero atoms selected from O, N, and S,
in an organic solvent, and optionally in the presence of a Lewis acid catalyst, resulting in a transfer of the group Y in order to yield a compound of the formula R N —Y.
7. Process according to claim 6 , wherein Y represents —CN, and said reacting is conducted for a direct electrophilic cyanation of a C—H bond in an organic compound.
8. Process according to claim 6 , wherein W represents CR 5 or C—CO 2 R 5 , and said reacting is conducted for a direct electrophilic alkynylation of a C—H bond in an organic compound.
9. An imidazolium sulfurane of the formula (I):
wherein:
R 1 and R 2 each independently represent alkyl, aralkyl, aryl, heteroaryl, each being optionally substituted by one or more hetero atoms selected from O, N, S or halogen, or R 1 and R 2 may together form a hydrocarbon ring structure, optionally substituted by one or more hetero atoms selected from O, N, S and halogen;
R 3 and R 4 each independently represent a lower alkyl group having 1 to 6 carbon atoms, each lower alkyl group being optionally substituted by one or more hetero atoms selected from O, N, S or halogen;
X is an anion selected from halogen or a non- or weak-coordinating anion;
Y represents a group of the —C≡W formula wherein W represents N, CR 5 ,
or C—CO 2 R 5 wherein R 5 is selected from the group consisting of C 1 to C 20 straight chain, branched chain or cyclic aliphatic hydrocarbons, optionally having one or more unsaturated bonds or C 6 to C 20 aromatic hydrocarbons and partially arene-hydrogenated hydrocarbons, each hydrocarbon optionally being substituted by one or more hetero atoms selected from O, N, S, halogen or a silylgroup.
10. The imidazolium sulfurane of the formula (I) as claimed in claim 9 , wherein R 1 and R 2 each independently represent alkyl.
11. Process according to claim 5 , wherein R—C≡W is trimethylsilyl cyanide.
12. An imidazolium sulfurane of the formula (I):
wherein:
R 1 and R 2 each independently represent hydrogen, alkyl, aralkyl, aryl, heteroaryl, each being optionally substituted by one or more hetero atoms selected from O, N, S or halogen, or R 1 and R 2 may together form a hydrocarbon ring structure, optionally substituted by one or more hetero atoms selected from O, N, S and halogen;
R 3 and R 4 each independently represent a lower alkyl group having 2 to 6 carbon atoms, each lower alkyl group being optionally substituted by one or more hetero atoms selected from O, N, S or halogen;
X is an anion selected from halogen or a non- or weak-coordinating anion;
Y represents a group of the —C≡W formula wherein W represents N, CR 5 ,
or C—CO 2 R 5 wherein R 5 is selected from the group consisting of C 1 to C 20 straight chain, branched chain or cyclic aliphatic hydrocarbons, optionally having one or more unsaturated bonds or C 6 to C 20 aromatic hydrocarbons and partially arene-hydrogenated hydrocarbons, each hydrocarbon optionally being substituted by one or more hetero atoms selected from O, N, S, halogen or a silylgroup.