CA2369043A1

CA2369043A1 - Novel ligands for chiral catalysis

Info

Publication number: CA2369043A1
Application number: CA002369043A
Authority: CA
Inventors: Kevin Burgess
Original assignee: Individual
Current assignee: Texas A&M University System
Priority date: 1999-04-08
Filing date: 2000-03-03
Publication date: 2000-10-19
Also published as: JP2002541262A; AU2925300A; GB9907895D0; EP1165574A1; CN1353718A; WO2000061589A1

Abstract

Novel phosphine oxazoline ligands of formula (I) wherein m is 1, 2, 3 or 4; n, p, q, r are independently zero or 1 provided that at least one of n, p, q and r is 1; X is O, S, Se, CH2, NH; Y is N, P, As, S; R is H; a straight-chain alkyl group, a branched-chain alkyl group or a cyclo alkyl group optionally substituted by one or more groups independently selected from alkyl, aryl, halo, alkoxy, amine, phosphine and ether groups; an aryl group optionally substituted by one or more groups independently selected from alkyl, aryl, halo, alkoxy, amine, phosphine and ether groups; ferrocenyl; a thioalkyl group; a thioaryl group; or R is derived from a hydrocarbyl group attached to a functional group of an organic compound or a polymer capable of giving rise to the grouping -N-C-X- in the ring structure of (I); R1 to R13 are independently selected from H; a straight-chain alkyl group, a branched-chain alkyl group or a cyclo alkyl group optionally substituted by one or more groups independently selected from alkyl, aryl, halo, alkoxy, amine, phosphine and ether groups; an aryl group optionally substituted by one or more groups independently selected from alkyl, aryl, halo, alkoxy, amine, phosphine and ether groups; with the proviso that when m is 1, one of n, p, q and r is 1 the remaining three being zero, X is O, Y is P, R1 and R2 are both H, R3 to R11 if present are H, and R12 and R13 are both phenyl, then R is not CH3, C(CH3)3, CHPh2, CPh3, adamantyl, C6H3(t-Bu)2, ferrocenyl, CF3, Ph, C6H4OMe, C6H4Me, C6H4NO2 or C6F5, a process for the preparation thereof, metal complexes containing such ligands and the use of such complexes, or combinations of ligand with metal salts or complexes, as catalysts for asymmetric syntheses.

Description

NOVEL LIGANDS FOR CHIRAL CATALYSIS
The present invention relates to novel optically active phosphine oxazoline ligands, a process for the preparation thereof, metal complexes containing such novel ligands and the use of such complexes, or combinations of ligand with metal salts or complexes, as catalysts for asymmetric syntheses.
The development of novel catalytic systems exhibiting unique reactivity and high enantioselectivity is of great importance in science and technology. The activity of many pharmaceuticals, agrochemicals, fragrances and food additives are associated with a specific enantiomer. Thus, the ability to produce enantiomerically pure compounds is ~ 5 essential. Many approaches have been explored to acquire such enantiomerically pure compounds, ranging from optical resolution and structural modification of naturally occurring chiral substances to asymmetric catalysis using synthetic chiral catalysts and enzymes. Asymmetric catalysis has been found to be one of the most efficient, if not the most efficient method of producing enantiomerically pure compounds since a small amount of a chiral catalyst can be used to produce a large quantity of a chiral compound.
One class of ligands which have played a significant role in the development of chiral catalysts are asymmetric phosphine ligands. Although over 1000 chiral diphosphine ligands have been prepared since the application of the DIPAMP
ligand in the production of L-Dopa, only a few of these have the efficiency and selectivity of commercial applications. Some of the most well known phosphine ligands used include BINAP, BPPM, DEGPHOS, DIOP, Chiraphos, Skewphos, Duphos and BPE all of which acronyms are described by annotated references in e.g. WO 97/47633 and are incorporated herein by reference. However, these ligands have their disadvantages and 3o are not ideal for all applications.
There is still, therefore, the need to develop novel chiral catalysts which are highly enantiomerically selective and carry out the required reaction giving a high yield.

Accordingly. the present invention provides a phosphine oxazoline ligand of formula (I) R~2 4 R; R8 R9 R ~ R
Y~Rt3 I
. -~R7 R~~, I
p r X
~N R
R
wherein mis1,2,3or4;
n, p, q, r are independently zero or I provided that at least one of n, p, q and r is 1;
X is O, S, Se, CH2, NH;
Y is N, P, As, S;
R is H; a straight - chain alkyl group, branched-chain alkyl group or a cyclo alkyl group optionally substituted by one or more groups independently selected from alkyl, aryl, halo, alkoxy, amine, phosphine and ether groups; an aryl group optionally substituted by one or more groups independently selected from alkyl, aryl, halo, alkoxy, amine, phosphine and ether groups; ferrocenyl; a thioalkyl group; a thioaryl group;
or R is ~ 5 derived from a hydrocarbyl group attached to a functional group of an organic compound or a polymer capable of giving rise to the grouping -N-C-X- in the ring structure of (I);
R' to R'3 are independently selected from H; a straight-chain alkyl group, a branched-chain alkyl group or a cyclo alkyl group optionally substituted by one or more groups independently selected from alkyl, aryl, halo, alkoxy, amine, phosphine and ether groups;
an aryl group optionally substituted by one or more groups independently selected from alkyl, aryl, halo, alkoxy, amine, phosphine and ether groups;
with the proviso that when m is 1, one of n, p, q and r is 1 the remaining three being zero, X is O, Y is P, R~ and R'' are both H, R3 to Rl ~ if present are H, and R'2 and R13 are both phenyl, then R is not CH3, C(CH3)3, CHPhz, CPh3, adamantyl, C6H3(t-Bu)2, ferrocenyl, CF3, Ph, CbH40Me, C6H4Me, C6H4N0~ or C6F5 By the term "alkyl'" we mean a straight. branched or cyclo alkyl group having any number of carbon atoms, for example from 1 to 14 carbon atoms. such as from I to carbon atoms. The cyclo alkyl groups may have one or more rings in its structure e.g.
adamantyl which has a fused tricyclic ring structure.

By the term "aryl'" we mean an aromatic monovalent hydrocarbyl group which include inter alia aryl, alkaryl and aralkyl groups. for example phenyl, benzyl, naphthyl, etc.
to Suitably, m is 1 or 2; preferably 1.
Suitably, at least two of n, p, q and r are 1. the remaining two may be zero or I ;
preferably, two of n, p, q and r are 1, the remaining two are zero.
Suitably, X is O, S, CHz or NH; preferably O.
Suitably, Y is P, N or S; preferably P.
In the above structure, R may be derived from a hydrocarbyl group attached to a 2o functional group of an organic compound or a polymer capable of giving rise to the grouping -N-C-X- in the ring structure of (I). Thus, R may be an alkyl group of a polyacrylic acid, polymethacrylic acid, a polyacrylonitrile or a polyamide, all of which are polymers carrying a function group capable of giving rise to the grouping -N-C-X- in the ring structure of (I).
A first embodiment of the invention provides a compound of formula (IA) Rz Ra Rs R~
R~z Y~ IA
X ~ N i' R

wherein m, X, Y. R. and R' to R' and R' ~ and R' ~ are as hereinbefore defined. provided that when m is 1. X is O. Y is P. R', R'. R'. R~' and R' are H, and R'~ and R'3 are both phenyl. then R is not CH;. C(CH3);. CHPh~. CPh;. adamanty-l. C~H3(t-Bu)~.
ferrocenyl.
CF3. Ph, C6H:~OMe. C~H.~Me. C6H~N0~ or CbF;.
A second embodiment of the invention provides a compound of formula (IB) IB
Ri3 R
wherein m, X, Y, R and R' to R' and R' ~ and R' 3 are as hereinbefore defined.
A third embodiment of the invention provides a compound of formula (IC) Rz Ra Rs Rs R9 R~
/R,z IC
X 3 ~ 'Y
N R6 R~ R»
R
to wherein m, X. Y, R and R' to R9 and R'' and R'3 are as hereinbefore defined.
A fourth embodiment of the invention provides a compound of formula (ID) RZ R4 R; Rs R9 Ii2 R~
ID
YwR~3 X ~ N~3R6 R~ R~ R> >
R
i 5 wherein m, X, Y. R and R' to R' 3 are as hereinbefore defined.
A particularly preferred embodiment of the invention provides a compound of R~ R~ R~ R,, R' Y~
X

the following structure:

O
N /P~Rn R~3 R
wherein R is a C~_.~ alkyl group optionally substituted by one or more groups selected from phenyl and halo; where said substituent group is phenyl it may be optionally further substituted by one to five substituents selected from the group consisting of halo, C»
5 alkyl, C,_4 alkoxy or nitro; ferrocenyl or adamantyl; and R''' and R'3 each of which may be a phenyl or cyclohexyl group.
Particularly preferred compounds include those of the following formulae:
,,, ,,,,,,,, O
' N ph~P~Ph ' N ph~P~Ph Ph t-Bu to (l la) (l lc) (S)-2-Phenyl-4-[(diphenyl- (S)-2-tert Butyl-4-[(diphenyl-phosphino)ethyl]oxazoline phosphino)ethyl]oxazoline O~ '''''''~ 0 Ph~P~Ph ~ N ph~P~Ph t-a (lld) (llb) (S)-2-(3,5-ditertiarybutylphenyl)-4- (S)-2-Adamantyl-4-[(diphenyl-[(diphenylphosphino)ethyl]oxazoline phosphino)ethyl]oxazoline 2o and (S)-2-Triphenylmethyl-4-[(diphenylphosphino)ethyl]oxazoline (1 le) Compounds of formula (I) are novel and accordingly a further aspect of the present invention provides a process for the preparation of a compound of formula (I).
Compounds of formula (I) may be prepared by the reaction of a compound of formula (II) s 4 R; R8 R9 R 1 R.. I
r Y~R> > .BH3 II
p ~3 X ~R~7 Rlqy 1 Pro R~~
R~
wherein m, n, p, q, r, X. Y and R~ to R'3 are as hereinbefore defined; R~'~
and RAs are alkyl groups which may be the same or different and Pro is a nitrogen protecting group, for example a butoxy carbonyl group (hereafter "BOC"), with a compound of formula (III) H.H+.Hal-III
R OR'6 wherein R is as hereinbefore defined. R'6 is an alkyl group, for example ethyl, and Hal is ~ 5 a halide group, for example chloride. The reaction is carried out by the addition of for example gaseous HCI, in the presence of an alcohol, such as methanol to the compound of formula (II), followed by the addition of a compound of formula (III) in the presence of a base, for example triethylamine, in a suitable solvent such as dichloromethane.
20 Compounds of formula (III) are known in the literature (Meyers, A.L;
Schmidt, W; McKennon, M.J., Synthesis, 1993, 250-262).
Compounds of formula (II) may be prepared by the reaction of a compound of formula (IV) R 1 R2 4 R; R8 R9 L
p '~ IV

1(1R11 Pro R»
R~s wherein m, n. p, q, r, X, R~ to R~s and Pro are as hereinbefore defined, and L
is a leaving group, such as e.g tosylate, iodide, triflate or bromide, with a compound of formula s LiYR~2R~3, wherein Y, R~'' and R'3 are as hereinbefore defined. The reaction is carried out in the presence of an organic solvent, such as THF, and with the addition of BH3.
Compounds of formula (IV) may be prepared from the corresponding alcohol of formula (V) 4 Rs R8 R9 OH
p '~ V

N R6 ~~ R1aR11 Pro Ria to R~s wherein m, n, p, q, r, X, R' to R'' and Pro are as hereinbefore defined. The reaction is carried out with a suitable compound to give the desired leaving group, L. For example if the leaving group is tosyl, the reaction is carried out with, e.g. tosyl chloride, in the 15 presence of a base such as e.g. triethylamine, and a suitable solvent, such as e.g. dichloromethane. A catalytic amount of 4-dimethylaminopyridine (DMAP) may also be added.
Compounds of formula (V) are known in the literature (Ksander, G.M.; de 2o Jesus, R.; Yuan, A.; Ghai, R.D.: Trapani, A.; McMartin, C.; Bohacek. R., J.
Med. Chem.
1997, 40, 495-505).

Compounds of formulae (II) and (IV) are also novel and accordingly form a further aspect of the invention.
A yet further aspect of the present invention provides a metal complex containing a ligand of formula (I) comprising a metal and optionally other ligands capable of stabilising the complex, e.g. chloride, acetate etc. Suitably. the metal is a transition metal; for example, the metal may be selected from the group consisting of Ni, Pd, Rh, Ir, Cu, Ag, Au and Zn.
to A metal complex of the present invention may be of use in any chemical reaction requiring an asymmetric catalyst. Examples of such reactions include but are not limited to Heck type reactions, Suzuki type reactions, allylation reactions.
cross-coupling reactions, hydrogenations, hydroformylations and isomerisation reactions.
Therefore, a still further aspect of the invention provides a metal complex of the invention for use in asymmetric catalytic reactions. Alternatively, the invention provides the use of a metal complex of the invention in asymmetric catalytic reactions. Alternatively, there is provided a method for performing an asymmetric catalytic reaction, said method comprising the use of a metal complex of the invention.
2o The metal complex of the invention may be formed in situ from a ligand of formula (I) and a suitable precursor complex or salt of a metal, which is preferably a transition metal as recited above. Therefore, a further aspect of the invention provides for the use of a ligand of formula (I) in combination with a metal complex or salt in asymmetric catalysis.
The invention will now be described by way of example only.
(51-N-tert-butoxvcarbonyl-aspartic acid diethyl ester (3).
Absolute ethanol (420 ml) was cooled in ice and acetyl chloride (71.4 ml, 1.03 mol) was added dropwise to generate HC1 in situ. After the addition, the reaction was stirred for additional 30 minutes. L-Aspartic acid (33.278, 0.25 mol) was added in one portion and the solution heated slowly after dissolution to reflux. Refluxing was continued until the reaction was complete as monitored by thin layer chromatography (TLC). The reaction mixture was then cooled to 25°C and the solvent was removed under reduced pressure. Further drying under vacuum gave crude diethyl L-aspartate hydrochloride (2) as a viscous oil which crystallised on standing to a white solid, yield:
60 g (100%). This material was used without further purification. Spectral data for this sample were consistent with those given in the literature'. '3C NMR (75 MHz, d6-DMSO) 169.1, 168.2, 70.0, 60.9, 48.5, 34.2, 14.9 and 13.9.
1o A sample of the diethyl L-aspartate hydrochloride (2) (57.5 g, 0.273 mol) was dissolved in water (59 ml) and dioxane (149 ml) then cooled to 0°C.
Triethylamine (74 ml, 0.53 mol), then di-tert-butyl dicarbonate (74.99 g, 0.34 mol) were added with stirring. The reaction mixture was then heated at 50°C overnight after which TLC (ethyl acetate-ethanol 1:1 ) indicated complete consumption of the starting material.
The solvent was removed in vacuum, aqueous citric acid (150 ml, 10 %, w/v) added to adjust the pH to 2-3. Diethyl ether (300 ml) was added and the organic phase was separated.
The aqueous phase was extracted with ether (4 x 250 ml), the combined ether extracts washed with brine (100 ml), dried over NazS04, concentrated under vacuum to give (3) (78.8 g, 99 %) as light yellow oil, which can be used without further purification.
2o Spectral data for this sample were consistent with those given in the literature2~ 'H NMR
(300 MHz, CDC13) 5.48 (1 H), 4.49 (m, 1 H), 4.12 (m, 4H), 2.90 (dd, J = 16.8 Hz, J =
4.6 Hz), 2.76 (d, J = 4.88 Hz, 1 H), 1.46 (s, 9H), 1.21 (t, J = 7.1 Hz, 3H), 1.20 (t, J = 7.1 Hz, 3H); '3C NMR (75 MHz, CDC13) 170.9, 170.8, 155.4, 79.8, 61.6, 60.9, 49.9, 36.7, 28.2, 14.0 and 13.9.
(,S~-2-(tert-Butoxycarbonylamino)-1,4-butanediol (4).
A stirred solution of (S~-N-ten-butoxycarbonyl diethyl L-aspartate (3) (47.41 g, 0.16 mol) in absolute ethanol (770 ml) was cooled in ice, then sodium borohydride (60.8 g, 1.6 mol) was added in 10 g portions. The cooling bath was removed when the reaction 3o subsided, and the reaction mixture was heated slowly to reflux for 1 h;
after this time TLC (EtOAc-EtOH 3:1 ) analysis indicated complete consumption of the starting material. The reaction mixture was cooled to 25°C, and the lumps formed were broken-up to give a slurry that was poured into brine (450 ml). The mixture was filtered, the filtrate concentrated in vacuum to ca. 100 ml, and was extracted with ether (6 x 300 ml).
The insoluble solid material was extracted by stirring in ether (4 x 1 L) for 2 h.
5 The combined ether extracts were dried over MgS04, filtered and concentrated to give (4) as a colourless oil (24.4 g, 73%), which crystallised on standing.
Spectral data for this sample were consistent with those given in the literature2. 'H NMR (200 MHz, d6-DMSO) 6.45 (d, J = 8.4 Hz, 1 H), 4.57 (t, J = 5.6 Hz, 1 H), 4.35 (t, J = 5.1 Hz. 1 H), 3.40 (m, 4H), 3.23 (m, 1 H), 1.62 (m, 1 H), 1.40 (m, 1 H), 1.36 (s, 9H); ~ 3C NMR
(50 MHz, d6-to DMSO) 155.5, 77.4, 63.5, 58.0, 49.6, 34.4, 28.3.
(S~-N-tert -butoxycarbonyl-4-(2-hydroxy)ethyl-2,2-dimethyloxazolidine (5).
2,2-Dimethoxypropane (87 ml, 0.707 mol) and p-toluenesulphonic acid monohydrate (1.33 g, 7mmol) were added to a stirred solution of the diol (4) (14.39 g, 70 mmol) in dichloromethane (319 ml) at 25°C. The reaction was monitored by TLC (ethyl acetate-hexanes 2:1 ) until complete (36 h). The reaction mixture was then washed with aqueous NaHC03 (5%, 2 x 50 ml), brine (50 ml), dried (MgS04) and concentrated to form a colourless oil, which crystallised upon standing. The ratio of the desired five-membered ring product (5) to the undesired six-membered ring product (6) was 6.4:3.6.
Recrystallisation from heptane gave (5) as colourless needles (8.2 g, 48%).
Spectral data for this sample were consistent with those given in the literature3. 'H NMR
(200 MHz, CDCl3) 4.17 (m, 1 H), 3.97 (m, 1 H), 3.86-3.42 (m, 3H), 3.33 (br, 1 H), 1.76 (m, 2H), 1.5 (s, 3H), 1.46 (s, 9H); 13C NMR (50 MHz, , CDCl3) 153.9, 93.6, 80.9, 68.2, 58.6, 53.9, 37.7, 27.7, 26.3, 24.3.
(S~-N-tert-butoxvcarbonyl-2,2-dimethyl-4-hvdroxvmethyl-1,3-oxazine (6).
A sample of pure (6) was isolated via flash chromatography using ethyl acetate/hexanes (3:1 v/v) as eluant. ~H NMR (200 MHz, CDC13) 3.37-3.77 (m, SH), 1.62 (m, 2H), 1.35 (s, 9H), 1.24 (s, 3H), 1.22 (s, 3H); 13C NMR (50 MHz, , CDCl3) 155.0, 101.2, 79.1, 63.8, 57.9, 48.5, 35.7, 28.3, 24.7, 24.6.

~S~-2-(tert-Butoxvcarbonvl-4-(4-toluenesulfonvloxvethvl)-2,2-dimethvloxazolidine Dry, freshly crystallised p-toluenesulphonyl chloride (1.86 g, 9.8 mmol) and 4-dimethylaminopyridine ( 10 mg, 0.082 mmol) were added to a solution of alcohol (5) (2.00 g, 8.15 mmol) and triethylamine (2.6 ml, 18.75 mmol) in dichloromethane (20 ml) at 5°C with stirring. The resulting solution was protected from moisture and kept at 5°C
until all the starting material (5) had reacted (33 h, TLC). A colourless solid, presumably triethylamine hydrochloride, crystallised out of the reaction, and was filtered away.
The filtrate was diluted with dichloromethane to a volume of 90 ml, and washed with water (2 x 20 ml), brine (20 ml), dried over Na2S04, and concentrated to give the crude tosylate (7) as white solid. This material was purified by dissolving in ether (ca. 330 ml), filtering through celite 545 on a wad of cotton wool to give 2.95 g (90 %) of (7).
'H NMR (200 MHz, CDC13) 7.78 (m, 2H), 7.35 (d, 2H), 4.09 (m, 2H), 4.09 (m, 2H), 3.90 (m, 2H), 3.73 (m, 1 H), 2.95 (m, 2H), 1.51 (s, 6H), 1.44 (s, 9H).
(S~-N-tert-butoxycarbonyl-4-ethylenediphenylphosphinoborane-2,2-dimethyloxazolidine (8).
n-Butyl lithium in hexanes (1.6 M, 17.1 ml, 27.4 mmol)was added to a solution of diphenylphosphine (4.52g, 24.3 mmol) and THF (100 ml) at 0°C. The orange-red 2o solution was stirred at 0°C for 30 minutes. A solution of tosylate (7) (8.44 g, 21.1 mmol) in THF (60 ml) was then added dropwise to the solution of the diphenylphosphide anion at 0°C. The reaction mixture was stirred for another 30 minutes. Borane-THF complex (1 M, 26 ml, 26 mmol) was added to the solution at 0°C and this was then stirred for an additional 20 minutes. The solvent was removed, and the remaining material was dissolved in ethyl acetate (600 ml) and washed with 1 M HCl~aq~ (100 ml), sat.
NaHC03 (100 ml), brine (100 ml), dried over Na2S04, and filtered. The solvent was removed under reduced pressure. The residue was then purified by column chromatography on silica gel using ethyl acetate/hexane eluant (3:7 v/v) to give 8.1 g (18.9 mmol, 90%) of a colourless oil, which crystallised upon standing at 25°C. m.p. 95.0-96.5°C; Rf 0.81 (ethyl acetate/hexane, 1:1 v/v). This was the protected phosphine (8). 'H-NMR
(CDC13, 300 MHz): 7.63 (m, 4H), 7.43 (m, 6H), 3.92 (m, 2H), 3.67 (m, 1H), 2.17 (m, 2H), 1.83 (m, 2H), 1.60 (s, 3H), 1.54 (s, 9H), 1.34 (s, 3H); '3C-NMR (CDC13, 7~ MHz):
151.9.
131.9-132.1, 131.2, 128.9, 128.8, 94Ø 19.9, 67Ø 57.4, 28.3. 26.7, 22.9.
22.3, 21.8; 3'P-NMR (CDC13, 121 MHz): 16.76 (br).
(S~-2-Phenyl-4-[(diphenvlphosphino)ethylloxazoline (lla).
The protected phosphine (8) (500 mg, 1.17 mmol) was dissolved in 8 ml of methanol and cooled to 0°C. Gaseous HCl was bubbled through the reaction for 5-10 minutes. The methanol was removed under vacuum and the residue was dissolved in 8 ml of 1,2-dichloroethane. Triethylamine (1.5 ml, 9.3 mmol) and benzimidic acid ethyl 1o ester hydrochloride4 (230 mg, 1.24 mmol) were added, and the reaction was refluxed for 6 h. The solvent was removed giving colourless oil, and the crude product was purified by column chromatography on silica gel using ethyl acetate/hexane eluant (2:8 v/v) to afford oxazoline (lla) (210 mg, 0.58 mmol, 50% yield) as a colourless solid.
m.p. 52.5-54°C; Rf 0.76 (ethyl acetate/hexane, 3:7 v/v). 'H-NMR (CDC13, 300 MHz):
7.93 (d, J
= 7 Hz), 7.29-7.49 (m, 13H), 4.34-4.49 (m, 4H), 4.00 (dd, J = 7.5 Hz, J = 7.5 Hz), 2.24-2.34 (m, 2H), 2.07-2.15 (m, 2H), 1.67-1.85 (m, 4H); 13C-NMR (CDCl3, 75 MHz):
163.7, 138.6, 138.3, 132.8, 132.6, 128.6, 128.5-128.2, 127.7, 72.2, 67.5 (d, J= 13.5 Hz), 32.1 (d, J = 16.5 Hz), 24.1 (d, J = I 1.5 Hz); 3' P-NMR (CDC13, 121 MHz): -15.8 I HRMS
(M+ + 1 ) m/z Calcd. for C23Hz3NOP: 360.15170. Found 360. I 5147.
General Procedure for Preparation of Oxazolines (1lb-e).
(~f)-2-Adamantyl-4-[(diphenylphosphino)ethylloxazoline (llb).
The protected phosphine (8) (500 mg, 1.17 mmol) was dissolved in 8 ml of methanol and cooled to 0°C. Gaseous HCl was bubbled through the reaction for 5-10 minutes, and the methanol was removed under vacuum. The residue was dissolved in 8 ml of 1,2-dichloroethane and triethylamine (0.44 ml, 4.lmmol), catalytic 4-dimethylaminopyridine (2 mg), then adamantanecarbonyl chloride (256 mg, 1.28 mmol) were added and reaction was stirred for 12 h. Subsequently, borane-THF (1 M, 2 ml, 2 mmol) was added to the reaction mixture at 0°C, and this was stirred for 10 minutes.
The reaction mixture was diluted with 1 S ml of dichloromethane and washed with HCl,aq~

(0.5 M, 10 ml x 2) and brine (10 ml), dried over Na2S0.~, filtered and concentrated.
1,4-Diazobicyclo[2.2.2]octane (656 mg, 5.85 mmol) and THF (8 ml) were added to this material. The reaction mixture was cooled to 0°C and methanesulphonyl chloride (86Y1, 1.28 mmol) was added. The reaction was stirred at 25°C for 4 h then heated to 50 °C for another 4 h. The resulting slurry was filtered and concentrated at reduced pressure, and the residue was flash chromatographed using ethyl acetate/hexane eluant (2:8 v/v) to give 370 mg (0.89 mmol, 75%) of the product (llb) as an oil. Rf 0.76 (ethyl acetate/hexane, 3:7 v/v)~H-NMR (CDC13, 300 MHz): 7.43-7.48 (m, 4H), 7.34-7.41 (m, 6H), 4.14-4.23 (m, 2H), 3.81 (m, 1H), 2.18-2.24 (m, 1H), 2.03-2.08 (m, 3H), 1.90 (m. 3H), 1.64-1.83 (m, 12H); '3C-NMR (CDC13, .75 MHz): 173.5, 138.6, 138.2. 132.9. 132.7. 132.4, 128.6-128.3, 71.5, 66.4 (d, J = 13.5 Hz), 39.6, 36.5, 35.1, 32.1(d, J = 16.5 Hz), 28.1, 23.6 (d, J = 11.5 Hz); 3'P-NMR (CDC13, 121 MHz): -15.81. HRMS (M+ + 1) m/z Calcd. for C2~H33NOP: 418.22998. Found 418.22583.
(S~-2-tert-Butyl-4-1(diuhenylphosphino)ethvlloxazoline (llc).
This compound was prepared via the same method used for compound (llb), but beginning with 500 mg of (8), 117 mg (0.34 mmol, 30%) of the oxazoline (llc) was produced as colourless oil. Rf 0.68 (ethyl acetate/hexane, 3:7 v/v). 1H-NMR
(CDC13, 300 MHz): 7.78 (s, 2H), 7.38-7.56 (m, 5H), 7.26-7.34 (m, 6H), 4.33-4.47 (m, 2H), 3.97 (t, J= 7 Hz, 1 H), 2.14-2.27 (m, 1 H), 2.04-2.12 (m, 1 H), 1.70-1.84 (m, 1 H), 1.65-1.70 (m, 1H), 1.33 (s, 18H); '3C-NMR (CDC13, 75 MHz): 174.0, 138.6, 138.2, 132.7, 132.4, 132.1, 128.6-128.3, 72.0, 66.6 (d, J = 13.5 Hz), 33.2, 32.1 (d, J = 16.5 Hz), 27.8, 23.6 (d, J= 11.5 Hz); 3'P-NMR (CDC13, 121 MHz): -15.37. HRMS (M+ + 1) mlz Calcd. for C21HZ~NOP 340.18303. Found 340.18281.
(S1-2-(3,5-Di-tert -butylphenyl)-4-1(diphenylphosphino)ethylloxazoline (l ld).
This compound was prepared via the same method used to prepare (llb).
Beginning with 500 mg of (8), 227 mg (0.48 mmol, 41%) of the oxazoline (lld) was produced as colourless oil. Rf 0.77 (ethyl acetate/hexane, 3:7 v/v). ~ H-NMR
(CDC13, 300 MHz): 7.38-7.44 (m, 4H), 7.27-7.37 (m, 6H), 4.21 (m, 1H), 4.12 (m, 1H), 3.80 (dd, J = 6.3 Hz, J = 7.8 Hz), 2.14 (m, 1H), 2.01 (m, 1H), 1.60 (m, 2H), 1.57 (s, 9H); ~3C-NMR (CDC13, 75 MHz): 164.4, 150.9, 138.5. 138.3, 132.9, 132.8. 132.6. 128.7-128.4, 127.0, 125.6. 122.5. 72Ø 67.5 (d. J = 13.5 Hz), 34.9, 32.1 (d, J = 16.5 Hz), 31.4. 24.0 (d, J = 12.0 Hz); 3' P-NMR (CDCl3. 121 MHz): -15.20. HRMS (M+ + 1 ) min Calcd. for C3,H39NOP 472.27693. Found 472.27524 (S1-2-Triphenvlmethvl-4-[(dinhenvlphosphino)ethvlloxazoline (lle).
This compound was prepared via the same method for compound (llb).
Beginning with 500 mg of (8), 191 mg (0.36 mmol, 31%) of the oxazoline (lle) was produced as colourless oil. Rf~ 0.71 (ethyl acetate/hexane, 3:7 v/v). ~H-NMR
(CDC13, 300 MHz): 7.25-7.50 (m. 25H), 4.35 (m, 2H0, 4.02 (m. 1H), 2.21 (m, 1H), 2.10 (m, 1H), 1.77 (m, 2H); '3C-NMR (CDC13, 75 MHz): 169.6, 143.4, 138.4, 138.2. 132.9, 132.6, 132.4, 130.1-126.5, 71.9, 66.8(d, J= 13.5 Hz), 61.4, 31.8 (d, J = 16.5 Hz), 23.7 (d, J = I 1.5 Hz); 3 ~ P-NMR (CDC13, 121 MHz): -15.51.
References:
1. (a) Williams, R.M.; Im, M-N., J. Am. Chem. Soc. 1991, 113, 9276-9286.
(b) Williams, R.M.; Sinclair, P.J.; Zhai, D.; Chen, D., J. Am. Chem. Soc.
1988, 110, 1547-1557.
2. Deaimoni, G.; Dusi, G.; Quadrelli, P.; Righetti, P.. Tetrahedron, 1995, 51, 4144.
3. Ksander, G.M.; de Jesus, R.; Yuan, A.; Ghai, R.D.; Trapani, A.; McMartin, C.;
Bohacek, R., J. Med. Chem. 1997, 40, 495-505.
4. Meyers, A.L; Schmidt, W; McKennon, M.J., Synthesis, 1993, 250-262.

Claims

1. A compound of formula (I) wherein m is 1, 2, 3 or 4;
n, p, q, r are independently zero or 1 provided that at least two of n, p, q and r are 1;
X is O; S, Se, CH2, NH;
Y is N, P, As, S;
R is H; a straight-chain alkyl group, a branched-chain alkyl group or a cyclo alkyl group optionally substituted by one or more groups independently selected from alkyl, aryl, halo, alkoxy, amine, phosphine and ether groups; an aryl group opdonally substituted by one or mere groups independently selected from alkyl, aryl, halo, alkoxy, amine, phosphine and ether groups; ferrocenyl; a thioalkyl group; a thioaryl group;
or R is a polymeric structure wherein the functional groups of the polymer are capable of reacting to produce the N-C-X- grouping in the ring structure of (I);and R1 to R13 are independently selected from H; a straight-chain alkyl group, a branched-chain alkyl group or a cyclo alkyl group opdonally substituted by one or more groups independently selected from alkyl, aryl, halo, alkoxy, amine, phosphine and ether groups; an aryl group optionally substituted by one or more groups independently selected from alkyl, aryl, halo, alkoxy, amine, phosphine and ether groups.

2. A compound according to claim 1, wherein m is 1 or 2.

3. A compound according to claims 1 or 2, wherein X is O, S, CH2 or NH.

4. A compound according to claim 3 wherein X is O.

5. A compound according to any one of claims 1 to 4 wherein Y is P, N or S.

6. A compound according to claim 5 wherein Y is P.

7. A compound according to any one of the preceding claims wherein the group R
is a polymeric structure wherein the functional groups of the polymer are capable of reacting to product the -N-C-X- grouping in the ring structure of (I), said polymeric structure being selected from the group polyacrylic acid, polymethacrylic acid, polyacrylonitrile and polyamide.

8. A compound according to claim 1 which is a compound of formula (IB) wherein m, X, Y, R1 and R7 to R12 and R13 and R13 are as defined in claim 1.

9. A compound according to claim 1 which is a compound of formula (IC) wherein m, X, Y, R and R1 to R9 and R12 and R13 are as defined in claim 1.

10. A compound according to claim 1 which is a compound of formula (ID) wherein m, X, Y, R and R1 to R13 are as defined in claim 1.

11. A compound according to claim 1 which is a compound of structure wherein R is a C1-4 alkyl group optionally substituted. by one or more groups selected from phenyl and halo; where said substituent group is phenyl it may be optionally further substituted by one to five substituents selected from the group consisting of halo, C1-4 alkyl, C1-4 alkoxy or vitro; ferrocenyl or adamantyl; end R12 and R13 each of which may be a phenyl or a cyolohexyl group.

12. A, compound according to claim 1 which is a compound selected from the group consisting of:
and (S)-2-Triphenylmethyl-4-[(diphenylphosphino)ethyl]oxazoline (11e)

13. A process for the preparation of a compound of formula (1) according to claim 1, said process comprising the reaction of a compound of formula (II) wherein m, n, p, q, r, X, Y and R1 to R13 arc as defined in claim 1; R14 and R15 are alkyl groups which may be the same of different and Pro is a nitrogen protecting group, with a compound of formula (III) wherein R is as defined in claim 1, R16 is an alkyl group, and Hal is a halide group.

14. A metal complex containing a compound according to any one of the claims 1 to 12 comprising a metal and optionally other ligands capable of stabilising the complex.

15. A complex according to claim 14 wherein the metal is a transition metal.

16. A complex according to claim 15 wherein the metal is selected from the group consisting of Ni, Pd, Rh, Ir, Cu, Ag, Au and Zn.

17. A metal complex according to any one of claims 14 to 16 for use in asymmetric catalytic reactions.

18. The use of a metal complex according to any one of claims 14 to 16 in asymmetric catalytic reactions.

19. The use of a compound according to any one of claims 1 to 12 in combination with known metal complexes or salts in asymmetric catalysis.

20. A method for performing as asymmetric catalytic reaction, composing the use of a metal complex according to any one of claims 14 to 16.

21. An intermediate of formula (II) wherein in, n, p, q, r, X, Y and R1 to R13 are as defined in claim 1; R14 and R15 are alkyl groups which may be the same of different and Pro is a nitrogen protecting group.

22. An intermediate of formula (IV) wherein m, n, p, q, r, X, R1 to R15 are as defined in claim 1, Pro is a nitrogen protecting group, and L is a suitable having group.