Perfluoro-n-alkylsulfonic acid derivatives

Details Perfluoro-n-alkylsulfonic acid derivatives Perfluoro-n-alkylsulfonic acid derivatives

2000-09-25

2002-03-05

Vollano, Jean F. (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Sulfonate esters

C568S008000, C568S017000

Reexamination Certificate

active

06353125

ABSTRACT:

The invention relates to novel bis(perfluoro-n-alkane-sulfonates) of the formula I:
where
n is 3, 4, 5, 6, 7, 8 or 9,
where nonadjacent groups ═CR— may be replaced by ═N—, and —CHR— may be replaced by —NR—, —O— or —S— and
R is alkyl or alkoxy having from 1 to 12 carbon atoms, halogen, —CN, —CF
3
, —OCF
3
or unsubstituted phenyl or phenyl which is monosubstituted or polysubstituted by alkyl or alkoxy having from 1 to 12 carbon atoms, halogen or —CN, where if more than one R is present the substituents R may be identical or different.
The invention also relates to a process for preparing the bis(perfluoro-n-alkanesulfonates) of the formula I and their use as precursors for the preparation of chiral phosphine ligands for transition metal catalysts.
Chiral phosphine ligands such as 2,2′-bis(diphenylphosphino)-1,1′-binaphthyl (BINAP) and analogous phosphines are of great importance as constituents of transition metal catalysts used in enantioselective hydrogenations or CC couplings. Various ways of preparing these phosphines are known in the literature. In general, these start from the corresponding binaphthols or analogous phenol derivatives whose hydroxy groups are converted into leaving groups and subsequently replaced by phosphine groups.
U.S. Pat. No. 5,399,771 discloses a process for preparing BINAP starting from enantiomerically pure binaphthol which is firstly converted into the corresponding bis(trifluoromethanesulfonate). BINAP is subsequently obtained by nickel-catalysed coupling with diphenylphosphine. Disadvantages of this process are the high price and the difficulty of industrial handling of the sensitive and extremely aggressive trifluoromethanesulfonic anhydride in the preparation of binaphthol bis(trifluoromethanesulfonate). The use of other trifluoromethanesulfonic acid derivatives such as trifluoromethanesulfonyl fluoride or chloride is also difficult in process engineering terms due to the high volatility of the compounds (b.p.=−20° C. and 32° C., respectively).
It is an object of the invention to provide a process which can be carried out industrially, does not have the abovementioned disadvantages and makes it possible to obtain, inexpensively and technically simply, compounds which are suitable as starting substances for the synthesis of chiral and phosphine ligands for transition metal catalysts.
It has surprisingly been found that the compounds of the formula I can be obtained in a simple manner by reacting the respective phenols with the corresponding perfluoro-n-alkanesulfonyl fluorides, chlorides or anhydrides and that significantly improved yields in the preparation of phosphine ligands for transition metal catalysts are obtained by use of the compounds of the formula I.
The corresponding relatively long-chain perfluoroalkanesulfonyl fluorides, chlorides or anhydrides are commercially available at favourable prices or can easily be prepared by known methods (e.g. DE 1912738, DE 42118562).
The invention accordingly provides bis(perfluoro-n-alkanesulfonates) of the formula I:
where
A, B and n are as defined above.
The invention further provides a process for preparing the bis(perfluoro-n-alkanesulfonates) of the formula I, characterized in that compounds of the formula II
where A and B are as defined above are reacted with the corresponding perfluoro-n-alkanesulfonyl fluoride, chloride or anhydride in the presence of a base.
The bis(perfluoro-n-alkanesulfonates) of the formula I prepared from the phenols of the formula II by the process of the invention are, in particular, valuable intermediates for the synthesis of chiral catalysts such as 2,2′-bis(diphenylphosphino)-1,1′-binaphthyl (BINAP) and analogous compounds.
A is preferably
B is preferably —(CHR
2
)
4
— or
in particular
n is preferably 3, 4, 5 or 7, in particular 3 or 7. n is very particularly preferably 3. R is preferably alkyl or alkoxy having from 1 to 7 carbon atoms, F, Br, CN, —CF
3
, —OCF
3
, in particular —CH
3
, —OCH
3
, CN or —CF
3
.
If R in the formulae above and below is an alkyl radical or an alkoxy radical, this may be linear or branched. It is preferably linear and has 1, 2, 3, 4, 5, 6 or 7 carbon atoms, and is thus preferably methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, methoxy, ethoxy, propoxy, butoxy, pentyloxy, hexyloxy or heptyloxy, also octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, octyloxy, nonyloxy, decyloxy, undecyloxy, dodecyloxy, tridecyloxy or tetradecyloxy.
The radical R can also be an optically active organic radical having an asymmetric carbon atom.
Above and below, halogen is fluorine, chlorine, bromine or iodine, preferably fluorine, chlorine or bromine. Halogen is particularly preferably fluorine or bromine.
Perfluoro-n-alkanesulfonates of the component formulae I1-I13 are particularly preferred embodiments of the invention.
I1

I2

I3

I4

I5

I6

I7

I8

I9

I10

I11

I12

I13
where R and n are as defined above and R
1
is alkyl or alkoxy having from 1 to 3 carbon atoms, F, Br, CF
3
or CN.
Very particular preference is given to the compounds of the formulae I1, I2, I3, I7 and I8.
The reaction procedure of the process of the invention for preparing the compounds of the formula I is simple, with the corresponding phenol derivative of the formula II being reacted with the corresponding perfluoro-n-alkanesulfonyl fluoride, chloride or anhydride at temperatures of from −30° C. to +70° C., preferably from −10° C. to +50° C., in particular from 0 to 30° C., under superatmospheric or subatmospheric pressure, preferably at atmospheric pressure, in the presence of a base. Preference is given to using perfluoro-n-alkanesulfonyl fluoride to obtain the perfluoro-n-alkanesulfonates of the formula I. As perfluoro-n-alkanesulfonyl fluorides, preference is given to using nonafluoro-n-butanesulfonyl fluoride or perfluoro-n-octanesulfonyl fluoride. Very particular preference is given to nonafluoro-n-butanesulfonyl fluoride.
The molar ratio of the respective phenol of the formula II to perfluoro-n-alkanesulfonyl fluoride, chloride or anhydride is, in the process of the invention, generally from 1:2 to 1:20, preferably from 1:2 to 1:10. A ratio of from 1:2 to 1:5 is particularly preferred.
The reaction can be carried out in the presence of equimolar amounts of base and perfluoro-n-alkanesulfonyl fluoride, chloride or anhydride or using an excess of the respective base.
Suitable bases for the process of the invention for preparing the compounds of the formula I are, for example, alkali metal carbonates and alkaline earth metal carbonates, for example sodium, potassium, magnesium or calcium carbonate. Particularly suitable bases are nitrogen heterocycles, amines or amidines. Preference is given to using nitrogen bases in which no H atoms are directly bound to an N atom. Preferred nitrogen bases are pyridines, pyrimidines, pyridazines, trialkylamines and dialkylarylamines, where the alkyl radicals in the trialkylamines and dialkylarylamines can be identical or different. Particular preference is given to imidazole, pyridine, p-dimethylaminopyridine, m-dimethylaminopyridine, o-dimethylaminopyridine, pyrimidine, trimethylamine, triethylamine, tripropylamine, triisopropylamine, dimethylaniline, diethylaniline. Very particular preference is given to pyridine, imidazole, p-dimethylaminopyridine, m-dimethylaminopyridine, trimethylamine, triethylamine and dimethylaniline. It is also possible to use mixtures of the nitrogen bases mentioned.
The reaction time is generally from 0.1 to 24 hours, preferably from 0.2 to 6 hours.
The reaction of the phenol with perfluoro-n-alkanesulfonyl fluoride, chloride or anhydride can be carried out in the melt or in solvents. Preference is given to carrying out the reaction in the presence of organic solvents.
Suitable solvents for the process for preparing the compounds of the formula I are halogenated hydrocarbons such as dichloromethane, trichloromethane, dichloroethylene or trichloroethylene, amides such as N,N-dimethylformamide or N

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