Optically active diamines and their use in catalytic processes
View Patent ↗The invention relates to stereoisomerically enriched diamines, to metal complexes comprising these diamines and also to their use in a process for asymmetrically reducing ketones using silanes, in particular polymethylhydrosiloxane, as reducing agents.
1. Compounds of the formula (I)
where
* marks stereogenic carbon atoms which each independently have R- or S-configuration, excluding meso-forms and
R 1 , R 2 , R 3 and R 4 are each independently hydrogen, C 1 –C 12 -alkyl, C 4 –C 24 -aryl or C 5 –C 25 -arylalkyl, or R 1 , R 2 , R 3 and R 4 together with ethylene bridge are 1,2-(C 5 –C 8 -cycloalkyl) and
R 5 and R 6 are each independently radicals which are selected from the group of —COOR 7 , —CONR 8 R 9 , —CN or —PO(OR 10 ) 2 where R 7 , R 8 , R 9 and R 10 are each C 1 –C 12 -alkyl, C 4 –C 24 -aryl or C 5 –C 25 -arylalkyl, or NR 8 R 9 as a whole is a cyclic amino radical having a total of 4 to 12 carbon atoms.
2. Compounds according to claim 1 , characterized in that R 1 , R 2 , R 3 and R 4 are each independently hydrogen, C 1 –C 8 -alkyl or C 4 –C 24 -aryl, or R 1 , R 2 , R 3 and R 4 together with the ethylene bridge are each 1,2-cyclohexylene.
3. Compounds according to claim 1 , characterized in that R 1 , R 2 , R 3 and R 4 together with the ethylene bridge are each (R,R)- and (S,S)-1,2-diphenyl-1,2-ethylene or (R,R)- and (S,S)-1,2-cyclohexylene.
4. Compounds according to claim 1 , characterized in that R 5 and R 6 are each independently selected from the group of —COOR 7 , —CONR 8 R 9 , —CN or —POOR 10 ) 2 where R 7 , R 8 , R 9 and R 10 are each C 1 –C 4 -alkyl or C 4 –C 24 -aryl.
5. The compound of claim 1 which is (1S,2S)- and (1R,2R)-bis-[N-(2-dimethylphosphonatoethyl)amino]cyclohexane, (1S,2S)- and (1R,2R)-bis-[N-(2-diethylphosphonatoethyl)amino]-cyclohexane, (1S,2S)- and (1R,2R)-bis-[N-(2-diphenylphosphonatoethyl)amino]cyclohexane, (1S,2S)- and (1R,2R)-bis-[N-(2-cyanoethyl)amino]cyclohexane, (1S,2S)- and (1R,2R)-bis-[N-(2-carboxylethylethyl)amino]cyclohexane and (1S,2S)- and (1R,2R)-bis-[N-(2-carboxylmethylethyl)amino]-cyclohexane, (1S,2S)- and (1R,2R)-bis-[N-(2-dimethyl-phosphonatoethyl)amino]1,2-diphenylethane, (1S,2S)- and (1R,2R)-bis-[N-(2-diethylphosphonatethyl)amino]-1,2-diphenylethane, (1S,2S)- and (1R,2)-bis-[N-(2-diphenylphosphonatoethyl)amino]-1,2-diphenylethane, (1S,2S)- and (1R,2R)-bis-[N-(2-cyanoethyl)amino]-1,2-diphenylethane, (1S,2S)- and (1R,2R)-bis-[N-(2-carboxyethylethyl)amino]-1,2-diphenylethane, or (1S,2S)- and (1R,2R)-bis-[N-(2-carboxymethylethyl)amino]1,2-diphenylethane.
6. Transition metal complexes containing compounds according to claim 1 .
7. Transition metal complexes according to claim 6 , characterized in that the ratio of transition metal to compounds of the formula (I) is 0.5 to 1.5.
8. Transition metal complexes according to claim 6 , characterized in that the compounds are zinc and cobalt complexes.
9. Transition metal complexes according to claim 6 , characterized in that the transition metal complexes are obtainable by reacting halides, carbonates, cyanurates, isocyanates, sulphates, phosphates, nitrates, carboxylates or alkoxides of zinc or cobalt with a compound of the formula (I)
where
marks stereogenic carbon atoms which each independently have R- or S-configuration, excluding mesa-forms and
R 1 , R 2 , R 3 and R 4 are each independently hydrogen, C 1 –C 12 -alkyl, C 4 –C 24 -aryl or C 5 –C 25 -arylalkyl, or R 1 , R 2 , R 3 and R 4 together with ethylene bridge are 1,2-(C 5 –C 8 -cycloalkyl) and
R 5 and R 6 are each independently radicals which are selected from the group of —COOR 7 , —CONR 5 R 9 , —CN or —PO(OR 10 ) 2 where R 7 , R 3 , R 9 and R 10 are each C 1 –C 12 -alkyl, C 4 –C 24 -aryl or C 5 –C 25 -arylalkyl, or NR 8 R 9 as a whole is a cyclic amino radical having a total of 4 to 12 carbon atoms.
10. Transition metal complexes according to claim 9 , wherein a reducing agent is used in the reaction.
11. Transition metal complexes according to claim 6 , characterized in that the transition metal complexes are prepared by reacting zinc compounds ZnY 2 or ZnYHal where Y is in each case independently hydrogen, BH 4 or an organic radical, and Hal is bromine, chlorine or iodine with a compound of the formula (I)
wherein
* marks stereogenic carbon atoms which each independently have R- or S-configuration, excluding mesa-forms and
R 1 , R 2 , R 3 and R 4 are each independently hydrogen, C 1 –C 12 -alkyl, C 4 –C 24 -aryl or C 5 –C 25 -arylalkyl, or R 1 , R 2 , R 3 and R 4 together with ethylene bridge are 1,2-(C 5 –C 8 -cycloalkyl); and
R 5 and R 6 are each independently radicals which are selected from the group of —COOR 7 , —CONR 8 R 9 , —CN or —PO(OR 10 ) 2 where R 7 , R 8 , R 9 and R 10 are each C 1 –C 12 -alkyl, C 4 –C 24 -aryl or C 5 –C 25 -arylalkyl, or NR 8 R 9 as a whole is a cyclic amino radical having a total of 4 to 12 carbon atoms.
12. Catalysts comprising transition metal complexes according to claim 6 .
13. Process for asymmetrically reducing ketones with silanes in the presence of catalysts, characterized in that the catalysts used are those according to claim 12 .
14. Process according to claim 13 , characterized in that the silanes used are those of the formula (V)
H r SiCl s (C 1 –C 8 -alkyl) t (C 1 –C 8 -alkoxy) u (phenyl) v (V)
where
r is one, two or three
and
( s+t+u+v )=(4 −r )
or polymethylhydrosiloxane (PMHS) having the repeating structural unit
15. Process according to claim 13 , characterized in that the amount of catalyst is in a molar ratio of transition metal to ketone used of 0.01 to 0.20.
16. Process according to claim 13 , characterized in that the ketones used are aryl ketones.