Asymmetric Hydroformylation. Hydroformylation of Olefins in the

20 Asymmetric Hydroformylation.

Downloaded by UNIV OF CALIFORNIA SAN FRANCISCO on December 14, 2014 | http://pubs.acs.org Publication Date: June 1, 1974 | doi: 10.1021/ba-1974-0132.ch020

Hydroformylation of Olefins in the Presence of Chiral Rhodium and Cobalt Catalysts P. PINO, G. CONSIGLIO, C. BOTTEGHI, and C. SALOMON Department of Industrial and Engineering Chemistry, Swiss Federal Institute of Technology, Zurich, Switzerland

Optical yields up to 17% and 25%, respectively, have been reached in the styrene hydroformylation in the presence of cobalt or rhodium catalysts using N-alkylsalicylaldimine or phosphines as asymmetric ligands. Furthermore the hydro formylation of aliphatic and internal olefins have been achieved using rhodium catalysts in the presence of opti cally active phosphines. With the same catalysts, cis -butene surprisingly undergoes asymmetric hydroformulation with optical yields up to 27%. On the basis of the results obtained for cis-butene and the asymmetric induction phenomena in dichlor(olefin)(amine)platinum(II) com plexes, a simple model is proposed for the catalytic complex. The correlation among the prevailing chirality obtained in the asymmetric hydroformylation of vinyl, vinylidene, and internal olefins is discussed.

A lthough the hydroformylation of olefins has been known since 1938, the first successful attempts to synthesize optically active aldehydes by hydroformylation using optically active catalysts have been pub lished only recently (1, 2, 3, 4). A l l the three possibilities to prepare optically active aldehydes (Scheme 1) have been successfully explored (5) using C o ( R * - S a l ) or [ C o ( C O ) ] and R * - S a l H ( R * - S a l H = ( S ) Ν-α-methylbenzylsalicylaldimine) as catalyst precursor, but the optical yields obtained were very poor. M u c h better results have been obtained 2

4

2

295 In Homogeneous Catalysis—II; Forster, D., et al.; Advances in Chemistry; American Chemical Society: Washington, DC, 1974.

296

HOMOGENEOUS


Table I.

CATALYSIS

II

Asymmetric Hydroformylation

Olefin

T,°C

Styrene Styrene Styrene a-Methylstyrene a-Methylstyrene a-Ethylstyrene 1-Butene 3-Methyl-1-pentene

120 90 90 120 90 120 120 120

c> R—CH—CH —CHO 2

2

2

R' H ,CO,cat* * R—CH—CH=CH > R—CH—CH —CH —CHO I partial | R' conversion R 2

2

2

2

r

+ R—CH—CH=CH

2

I R' Scheme 1

In Homogeneous Catalysis—II; Forster, D., et al.; Advances in Chemistry; American Chemical Society: Washington, DC, 1974.

20.

PINO

Rhodium Chiral and Cobalt Catalysts

ET AL.

297

in the Presence of Cobalt Catalysts" Optically Active Aldehyde Optical Yield,

Yield,

%

%

Absolute Configuration

2-pheny lpropanal 24 S 1.9 2-phenylpropanaldiethylacetal 15 15.2 R 2-pheny lpropanal 20 0.3 R S-phenylbutanaF 11 2.5 S S-phenylbutanaldiethylacetal 5 0.6 R 3-phenylpentanal 2.5 1.4 S 2-methylbutanal 15 90%).

Table III.

Catalyst [Rh(CO) Cl] 2

6

Asymmetric Ligand

2

[Rh(C H )Cl] 10

(+)—RhCl(CO)L 3

3

2

Rh/P

t;c

*/Ph° (-)-P-Pr

1/2.7

80

*/Ph» (+)-P-CH -Ph

1/10

120

^Ph" L = P^-Ph Tieo-menthyl (-)-DIOP

1/1

75

1/2

25

2

2

HRh(CO)(Ph )

Rhodium Catalyzed Styrene Hydroformylation

c

" The optical purity is not specified. * Optical purity ~ 94%.


20.

PINO

ET


AL.

301


Rhodium Catalyzed Asymmetric Hydroformylation The first successful experiments of asymmetric hydroformylation in the presence of rhodium catalysts and optically active phosphines as asymmetric ligands were carried out on olefinic substrates containing phenyl rings (2, 3, 4, 6, 18). Tables II and III show the most important results that have been previously reported. Optically active monophosphines containing optically active phosphorus atoms, chiral asymmetric alkyl or cycloalkyl groups, and chiral diphosphines were used as asym metric ligands. The nature of the chiral ligand seems to have a remark able influence on the optical yield as seen in Table III. A t high tempera ture and pressure, an increase in optical yield was observed using a large excess of chiral ligand (3). Furthermore, the optical yields are definitely higher for vinyl than for vinylidene olefins, demonstrating that the type of substrate has a remarkable influence on the asymmetric induction. The success achieved in the asymmetric hydroformylation of allylbenzene (6), the first olefin with a non-conjugated double bond used in such reactions, prompted an investigation of the asymmetric hydro formylation of aliphatic olefins using H R h ( C O ) ( P P h ) as the catalyst precursor and ( — ) - D I O P (see footnote to Table II) as the asymmetric ligand (7). As shown in Table IV, an optical yield of 27% was obtained using ds-butene, but it was remarkably lower using the corresponding rrans-olefin. The optical yields obtained using α-olefins are only slightly lower than those observed for styrene under similar conditions whereas only very low optical yields were obtained using vinylidene olefins. 3

3

d

The stereoelective hydroformylation of (R)(S)-3-methyl-

1-pentene

also has been achieved with rhodium catalysts; the optical purity of the in Aromatic Solvents Using Different Asymmetric Ligands ot-Phenylpropanal Pco, atm

PH2, atm

100

100

50

50

50

50

0.5 c d

0.5

Yield, %

Prevailing Chirality

Optical Purity, %

S

21.1

4

90

S

17.5

3

29

S

0.8

2

69

R

22.7

6

d

Optical purity ^ 90%. Not determined.


Ref.

302

HOMOGENEOUS CATALYSIS

Table IV.

Π

Hydroformylation of Aliphatic Olefins with HRh(CO) [Olefin/Rhodium = 3.0 · 10

2

Total Pressure, atm"


Olefin

Isomeric Reaction Products Composition

T., °c

l

12.5'

1-Butene 1-Pentene 2-Ethyl-l-hexene 3-Methyl-l-butene 1-Octene cis-Butene cis-Butene cis-Butene* irans-Butene cis-2-Hexene

1 81 1 1 1* 84 86 84 82

25 25 100 25 25 20 95 95 98 95

irans-2-Hexene

82

95

1.4'

1

40

> 95% 4-methylhexanal

3-Methyl-l-pentene "

b

13.5 >98% 3-ethylheptanal 13.5 9 e

d

e

( (

< >98% 2-methylbutanal i.y

° Starting pressure measured at room temperature. Partial pressure of the olefin: 0.33 atm. Straight chain aldehyde/Branched aldehyde. 4-Methylpentanal/2.3-Dimethylbutanal ratio. 6 c

d

recovered aldehyde at 50% conversion being remarkably higher (4.6% ) than with cobalt at high temperature and pressure. The influence of the different reaction variables (pco, PH > temperature, catalyst concentra tion, etc.) on the optical yield has not been investigated systematically. It seems, however, that i n the presence of the catalytic system ( H R h ( C O ) ( P P h ) / ( — ) - D I O P ) , the optical yields are higher at lower carbon monoxide and hydrogen pressure and at lower temperature (Table V ) . 2

3

3

Table V. Influence of the Reaction Conditions on the Optical Yield in the Hydroformylation of Different Olefins with HRh(CO) ( Ρ φ ) 3 and ( - ) - D I O P ; p = Pco 3

H2

Reaction Conditions

β 6

Olefin

T, °C

Total Pressure, atm"

1-Butene 1-Butene cis-Butene cis-Butene 1-Octene 1-Octene

100 25 95 20 95 25

80 1» 84 1» 84 1

Optical Purity of the Obtained Aldehyde, % 3.8 18.8 8.1 27.0 2.5 16.5

Starting pressure measured at room temperature. Partial pressure of the olefin = 0.33 atm.


20.

PINO

E T A L .


303

(PPh ) and (— )-DIOP (Molar Ratio 1/4) in Aromatic Solvents - 1.6 · 10 ; W * c o — 1 ] 3

3

3

Isolated Optically Active Compounds


2-methylbutanal 2-methylpentanoic acid 3-ethylheptanal 2,3-dimethylbutanal 2-methyloctanal 2-methylbutanal 2-methylbutanal 2-methylbutanal 2-methylbutanal 2-methylhexanoic acid 2-ethylpentanoic acid 2-methylhexanoic acid 2-ethylpentanoic acid 4-methylhexanal e f 0

(neat)

Chirality

Optical Purity, %

-5.27° -3.62° -0.02° -4.38° -4.91° +7.57° +2.28° +2.22° +0.89° +1.68° -0.22° +0.31° -0.11° -0.44°

R R R R R S S S s s R S R R

18.8 19.7 1.1 15.2 15.2 27.0 8.1 7.9 3.2 7.6 5.8 1.4 2.9 4.6

«D

Compound

(!=•?)

2 5

Rh 0 as catalyst precursor. 2-Methylhexanal/2-ethylpentanal ratio. l)(o.p.3,3%). The recovered olefin had 9 9 % ; the carbon monoxide contained < 1% hydrogen by G L C silica gel, 4 m X 1/8 inch, 70 °C, Perkin-Elmer F 11 hot wire gas chromatograph and argon as carrier gas. A l l hydroformylation experiments were performed with a 1:1 mix ture of carbon monoxide and hydrogen. The olefinic substrates were Fluka A G pure or very pure grade. a-Ethylstyrene, prepared according to Ref. 21, was > 98% pure by G L C . Dicobalt octacarbonyl (22), (S)-N-a-methylbenzylsalicylaldimine (R*-SalH) ( J ) ( M D + 1 8 3 ° ) and ( -)-2,3-0-isopropylidene2,3-dihydroxy-l,4-bis(diphenylphosphino)butane ( D I O P ) (23) ([

Asymmetric Hydroformylation. Hydroformylation of Olefins in the

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