CA1239647A - INTERMEDIATE FOR THE SYNTHESIS OF OPTICALLY ACTIVE D- .alpha. TOCOPHEROL - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

Optically active alpha-tocopherol is synthesized by a multi-step process using phytol as a starting material and the novel intermediate of the present invention. The overall process does not require an optical resolution step.

Description

This invention relates to an intermediate for use in the synthesis of optically active alpha-tocopherol.
The present application is divided from applica,nts copending Canadian application Serial INo. 396522 :Filed on February 18, 1982 ~ihich related to a process for preparino an optically active alpha-tocopherol of the formula HO ~ ' ~ ICH3 lCH3 3 ~ ~A-(cH2cH2cH)(CH2C~2CH2CH ~ CH3 CP.3 wherein A is ~ ~ CH -or ~ /JCH~-CH~3 2CH3 which comprises effecting cyclization of an optically active compound of che formula CH

~ G -~CH2CH2CH2CH)3 CH

H3C ~

OH OH

wherein G is -C- or -C-to obtain said optically active alpha-tocophero], wherein the cyclization reagent is d-camphor sulphonic acid in an inert solvent.
- 1 - 3~-P `'~
,~

9~

The compound d-alpha-tocopherol is the principal compound present in natural vitamin E sources. At present, d-alpha-tocopherol and other tocopherol derivatives are used in pharmaceuticals, foods and animal feeds.
Because d-alpha-tocopherol must generally be extracted from natural sources, such as vegetable oils, it is not suitable for industrial mass production. The content of d-alpha-tocopherol in vegetable oils is very small, and it is essential to purify d-alpha-tocopherol by separating it from beta, gamma and delta tocopherol isomers.
Several attennpts to synthesize optically active alpha-tocopherol have been reported; for instance, see H. Mayler and 0. Isler et al, Helv.
Chim. Acta. _, 650 ~1963); J. W. Scott, W. M. Cort, H. Harley, F. T.
Bizzarro, D. R. Panish and G. Saucy, J. Amer. Chem. Soc. 51, 200 (1974);
ibid 52, 174 (1975); Helv.Chim. Acta. 59, 290 ~1976); K. K. Chan, and N.
Cohen et al, J. Org. Chem. 41, 3497, 3512 (1976); ibid 43, 3435 (1978).
None of these methods are suitable for industrial mass production.
Known methods, including those cited above, require an optical resolution step, and this causes a serious reduction of the yield of about 30 to 40%. The present inventors have conducted research in order to achieve a method of synthesis that does not require an optical resolution step.
According to the present invention, there is now proviled a process for preparing an optically active compound of the formula IX
CH3 cl~l3 R20 ~ ~ ~ E t C1l2CH2CH2CH ~ CH3 Il C / ~ OR3 ~;~3~3~,4'7 \ ~CH3 \ ~C~-13 wherein E is C or ~C , and Rl, R2 and R3 are protecting groups for hydroxyl functions which comprises catalytically hydrogenating the double bond in the aliphatic chain of a com-pound of formula VIII

R2 ~ ~f~ /E~cl-l2c~l2cll2c~l}~cH3 ~13C~ 3 ~ CH3 \ ~CH3 wherein E is ~C or ~C , and R10 Rl~
Rl, R2 and R3 are protecting groups for hydroxyl functions. The novel inter-mediate of formula IX represents one of a number of steps involved in the formation of optically active alpha-tocopherol from phytol.
The present invention further provides the step of converting the compound of formula IX to a compound of formula X

~ \ ~ ~ Q -(cH2cH2cH2cH ~ C1-13 ORl O~Rl wherein Q is -C- or -C-C~13 CH3 and Rl is a protecting group for a hydroxyl function by removal of all of the protecting groups Rl, R2 and R3 following by oxidation.

- 2a -~L~3~ 7 The present invention, together with that of aforementioned parent application Serial No. 396,522 and copending divisional applications '1~ Serial Nos. ~ , G '~ 7 and ~ ~ Ç , will now be described in more detail.

~ ~3964'7 HO /~\~ C1i3 CH3 C~3 H3C ~V~\J\ ( I ) CH3 natural phytol HO'/ ~3 H3C ( I I ) HO '/--\ ~CH3 CH~, C-~3 C~3 HO~ = (III) HO~ ~3 R I ( I V ) OHC
~ C113 - 3 CH3 CH3 O~ \~ (V) .

¦ 3 r OF~3 ~ 3~ 6~ ~
OH

R~O ~ I~CH3 ( - 3 H3C OR3 ~ ~ (VII) H3C~ ~ (VIII) C~ OR~ CH3 CH3 CH3 H3C ~ (IX) CH3 ~ CH3 CH3 CH3 ( X ) H3C ~ o CH3 CH3 HO ~ CH3 .CH3 CH3 C ~ O ~ H (XI) C~!3 CH~ 3 d-~-tocopherol [(2R, 4'R, 8'R)-~-tocopherolJ

123~64~

In the structural representations of the compounds given throug]lout this application, Rl~ R2, R3 and R~, which are the same or different, indicate protecting groups of the hydroxyl function, and X
indicates halogen. A wedge-shaped line ( ~) indicates a substituent whicl protrudes out of the plane of the paper towards the reader, that is, the particular substituent is above the overall plane of the molecule. A
broken line (-= ) indicates a substituent which protrudes out of the plane of the paper in tlle direction away from the reader, tha-t is, the particular substituent is below the overall plane of the molecule. A wavy line (~ ) indicates a mixture of two compounds, each of which has the substituent, but wherein the substituent is above the plane for one compound and below the plane for the other.
A detailed description of one embodiment of this invention is as follows.
The compound of formula I (natural phytol) is converted to the compound of formula II or II' ~see below) by enantio selective oxidation.
This oxidation is carried out with natural phytol (I), diethyl tartrate, titanium tetraisopropoxide and t-butyl hydroperoxide, in a halogenated hydrocarbon solvent, such as di-chloromethane, trichloroethane, etc., at a temperature in the range of -70C to 30C. In carrying out this reaction, any tartrate ester can be utilized. Preferred tartrate esters include dimethyl tartrate and diethyl tartrate. If D-~-)- diethyl tartrate is utilized, then the compound of the formula II will ~2~ 7 be produeed. If the L-(+)- diethyl tartrate is utilized, then the compound of the formula (II') given below will be produeed.

HO ~ 0 C~3 CH3 CH3 H3C ~ ( II ) The eompound of the formula (II') is ultimately con-verted to an optieally active alpha-tocopherol eompound, namely, (2S, 4'R, 8'R) alpha-tocopherol in the manner illustrated above.
In aceordanee with this invention, the term "optieally active alpha-tocopherol" relates both to eompounds of (2R, 4'R, 8'R)-alpha-tocopherol and (2S, 4'R, 8'R)-alpha-tocopherol. The process for synthesizing (2S, 4'R, 8'R) alpha-tocopherol starting from the compound of the formula (II') is as follows.

H 0/--¦¦ C~~3 C ~13 ~ H3 H3C/= (I) C~3 natural phy to 1 '' CH~ C H3~ CH3 H 3C / ~/ \~\/\~, \/\~ ( I I ' ) HO~--~CH3 U3 C~i3 CH3 H O ~ ( I I I ' ) H O "'I H3 C U3 C H3 CH3 iL23~7 OHC
CH3 CH3 CH3 C~J3 O ~\~\CH3 (V' ) R20~ CH3 CH3 CH3 CH3 H3C~OR3 ~ ~ ( VI I ) ~1~3 ~ Rl b ~3 C H3 CU3 H3C ~ f ~ (VIII
CCHH33 ORI 1 C~3 CH3 CH3 H~C ~CH~ ( IX

:ELZ39~7 C~3 ~ ~ C~3 C~13 CH3 H~C ~ ~ H3 Cl 13 HO~ ~ C~,3 CH3 1~3 H3~oJ~ "I/V\ = (XI ' ) C~3 CH3 (2S, 4'R, 8'R)-cl-tocopherol `` i~3g~

The compound of formula (II) or (II') is con-verted to the compound of formula (III) or (III') by reductive cleavage of the epoxide. Among the con-ventional reducing agents usable in this reaction lithium aluminum hydride is preferred. In carrying out this reaction, an ether solvent, such as diethyl ether, tetrahydrofuran, etc., is used. The reaction temperature is not critical, but generally this re-action is carried out at a temperature in the range of from about -10C to about 40C.
The compound of formula (lII) or (III') is converted to the compound of formula (V) or (V') via the compound of formula (IV) or (IV'). First the 3-hydroxyl group is protected wi~h a protecting group Rl, and then the 1-hydroxyl group is oxidized to form the aldehyde of formula ~V) or (V'). In carrying out the formation of the compound of formula (IV) or (IV'), both the primary alcohol is protected, and the tertiary alcohol is protected. Then the protecting group of the primary a]cohol is removed to afford the compound of formula (IV) or (IV').
The compound of formula (IV) or (IV') is con-verted to the compound of formula (V) or (V') by oxi-dation. The entire reaction sequence is as il-lustrated below, first for the case of starting com-pound (III) and then for the case of starting compound (III').

~2~9~

HO---l CH CH3 CH3 CH3 HO~ ` (III) 1~40 ~1 3 H0 ( I I I-a ) Rl~ (III-b) H0 , I ~3 C113 C ~3 ~ 2~9~4~7 OHC

~1~ (V) HO~ CH3 ~H3 CH3 C~3 H0 G~ ( I I I ' ) c~3 R4U /--1 H3 3 CH~ c~3 HO ~ H3 ( I I I ' -a ) ~4~`~1 H3 C~3 CH3 CH3 ~/~ (III '-b) ~3~6~7 HO ~ CH3 R~ (IV' ) OHC\
1~CH3 3 CH3 CH3 C~3 ~23~

The compou~d of formula (III) or (III') is converted to the compound of formula (III-a) or (III'-a) by protecting the primary alcohol with a protecting group which will react only with the primary alcohol.
Any conventional protecting group reacting only with a primary alcohol can be utilized. Therefore, in the above structures, R4 denotes a protecting group that reacts only with a primary alcohol. Among the protecting group reactants, ester derivatives such as acetyl chloride, propionyl chloride, butyroyl chloride and pivaloyl chloride are preferred. In using these carboxylic acid chlorides, the reaction conditions are not critical and the reaction is carried out in an amine solvent, such as pyridine, trimethylamine or triethylamine, at a temperature of from about 0C to about 70C.
The compound of formula (III-a) or (III'-a) is converted to the compound of formula (III-b) or (III'-b) by protecting the tertiary alcohol. Any protecting group reactants that react with a tertiary alcohol can be utilized. Therefore, in the structures shown above, Rl represents a protecting group that reacts only with a tertiary alcohol. Conventional protect-ing groups usable in the invention include alkyl, aryl, alkoxyalkyl and aralkyl groups. The preferred group for use in this reaction is methoxymethylene.
In carrying out this reaction, a methoxymethylene halide, such as methoxymethylene chloride or methoxy-methylene bromide, can be used,in a solvent of di-chloromethane, dichloroethane, diethyl ether, or thelike.
The compound of formula (IlI-b) or (III'-b) is converted to the compound of formula (IV) or (IV') by ~L~3~

removing the protecting group in position 1. Any conventional method for reacting only with the pro-tecting group in position 1 can be utilized. Among the conventional methods of saponification that can be used to remove the protecting group, basic hydrolysis reactions utilizing potassium hydroxide, sodium hydroxide, sodium carbonate, etc. can be used.
In carrying out this reaction, the use of lithium aluminum hydride in an ether solvent is preferred, usable ethers including diethyl ether, tetrahydro-furan, and the like.
The cornpound of foxmula (IV) or (IV') is con-verted to the compound of formula (V) or (V') by oxidation of the primary alcohol to an aldehyde.
In carrying out this reaction, chromic acid reagents, such as pyridinium chlorochromate (PCC) or Collins reagent (chromic anhydride-pyridine) can be utilized in a dichloromethane, dichloroethane or trichloro-ethane solvent,at a temperature of from about 0C to about 40C.
The compound of formula (V) or (V') is con-verted to the compound of formula (VII) or (VII') by reaction with the compound of formula (VI). In the compound of formula (VI), X designates a halogen atom, such as chlorine, bromine and iodine. The corn-pound of formula (VI) designates 1,4-protected

2-halo-3,5,6-trimethyl-1,4-hydroquinone. R2 and R3 are the same as for Rl in the compound of formula (III-b) or (III'-b).
In carrying out this reaction, alkyl, aryl, alkoxyalkyl and aralkyl protecting groups can be used as R2 and R3. Among these, the preferred protecting group is methoxymethylene. The compound (VI) formed 1~396~

thereby is 2-halo-3,5,6-trimethyl 1,4-hydroquinone dimethoxymethyl ether.
The compound of formula (V) or (V') is converted to the compound of formula (VII) or (VII') by a Grignard reac-tion. In carrying out this reaction, the preferred solvents are ethers, such as diethyl ether, tetrahydrofuran, dioxane, etc. In carrying out the reaction, temperatures of from about 0C to about 50~C are generally utilized.
The compound of formula (Vl) is prepared as follows. 3,5,6-trimethyl-1,4-benzoquinone is con~
verted to compound (VI) first by treatment with halo-gen, followed by reduction to afford a halogenated hydroquinone. The hydroxyl groups are then pro-tected with methoxymethylene groups. The structure is illustrated in the case below wherein X designates bromide and R2 and R3 designate methoxymethylene groups.

.. . .
, _ _ _ . , .... . . , . , _ .. .... , . _ . ___ ._ .. _ .... ..

3~

O O

H 3 C / ` CH ( 1 3 H 3 C i~l~ ` 3 r (i) (ii) f/--OCH3 1) N a B H4 H3C~ 3 E t O H I
> I
2) E t ON a , ~ J~
CH30CI12Cl H3C ~/ Br ~_ OCH3 ( iii ) ~;~3~6~7 The compound of formula (VII) or (VII') is converted to the compound of formula (VIII) or (VIII') by dehydration. Any conventional dehydration method can be used for this purpose. Such conventional methods include chlorination by thionyl chloride to afford a chlorinat~d compound followed b~ dehydro-chlorination with diazabicycloundecene (DBU) or diazabicyclononene (DBN). Any conventional inert solvent, such as diethyl ether, tetrahydrofuran, benzene or toluene, can be used for the chlorination.
III carrying out this reaction, the temperature is not critical. Generally temperatures of from about 0C
to about 50C are utilized. In carrying out the dehydrochlorination, inert solvents, such as dimethyl sulfoxide, benzene and toluene are used.
The compound of formula (VIII) or (VIII') is converted to the compound of formula (IX) or (IX') by catalytic hydrogenation of the double bond on the aliphatic chain. Any conventional catalyst, such as palladium-charcoal, Raney nickel, platinum oxide, rhodium-aluminum, etc., can be used. In carrying out this reaction, temperatures of from about 0C to about 80C and solvents of ethanol, methanol, propanol, acetic acid, benzene, toluene, diethyl ether, etc., are utilized.
The compound of formula IX or IX' is converted to the compound of formula X or X' by removal of all of the protecting groups Rl, R2 and R3, followed by oxidation. The compound of formula X or X' can be prepared from the compound of formula IX or IX' via the compound of formula IX-a or IX'-a.

:1~3~ Eii4~

CU3 ORl cH3 CH3 C~3 O ~
~3C~o CU~3 CH3 CH3 (IX-a~

CH3 ~1 CH3 CH3 CH3 o H3CJq~o C1~3 CH3 CH3 ( IX ' -a ) 3~

The compound of formula (IX-a) or (IX'-a) can be isolated,but such a step is not essential.
Any conventional method of removing the protect-ing groups can be utilized to form the compounds of formulas (X) and (X'). Among the preferred methods for removing the protectin~ groups are treatment with acetic acid, hydrochloric acid-methanol, sulfuric acid-methanol or palladium-charcoal in a hydrogen atmos-phere. Any conventional method of converting hydro-quinone to quinone can then be utilized to completethe reaction. Preferred oxidizing reagents include lead dioxide, silver oxide, hydrogen peroxide, Fremy's salt, etc.
The compound of formula (X) or (X~) is converted to the compound of formula (XI) or (XI') by acidic cyclization to provide optically active alpha-tocopherol. Among the acids,d-carnphor sulfonic acid is preferred. In carrylng out this reaction, an inert solvent, such as methanol, ethanol, propanol, acetic acid and diethyl ether, is used,a-t a temperature of from about 0C to about 90C,to provide optically active (2R, 4'R, 8'R) alpha-tocopherol. In carrying out this reaction, the procedure described in O. Isler et al,Helv. Chim. Acta., 50, 1168 (1967) can also be utilized.
(2R, 4'R, 8'R) alpha-tocopherol synthesized ac-cording to the invention was fully characterized physically and chemically by comparison with naturally occurring d-alpha-tocopherol. For instance, the [~]D
value of acetate of (2R,4'R, 8'R) alpha-tocopherol synthesized according to the invention, and the oxida-tion product produced by treatment of (2R, 4'R, 8'R) alpha-tocopherol with potassium ferricyanide absolutely 3~64~7 correspond with the results obtained using authentic natural tocopherol.
The following intermediates in this invention are novel compounds: (II), (II ' ), (III), (III ' ), (IV), (IV' ), (V), (V' ), (VII), (VII ' ), (VIII), (VIII ' ), (IX), (IX'), (III-a), (III'-a), (III-b~, (III'-b), (IX-a) and (IX'-a).
The present invention is of great value because optical resolution is not absolutely necessary in order to produce optically active alpha-tocopherol by the process of the invention.
The following examples are illustrative of the invention, but the invention is not limited thereto.

Synthesis of (2S, 3S)-epoxy-(3S, 7R, llR)-3,7,11, 15-tetramethylhexadecane-1-ol (formula II') A solution of 11.4 y (40 mM) of titanium tetraiso-propoxide and 8.24 g (40 mM) of L-(+)-diethyl tartrate in 400 ml of dry dichloromethane was stirred at -20C to - 30C in a nitrogen atmosphere. After stirring for 10 min., 12 g (40 mM) of natural phytol in 30 ml of dry dichloromethane was added and then a dichloroethane solution co~taining 80 mM of t-butyl hydroperoxide was added. The reaction was monitored by thin layer chromatography (tlc). (CHC13 - benzene solvent).
After stirring for 2 hours at -20C to 30C, 100 ml of 10~ tartric acid solution was added and the drying bath was then removed. The organic layer was separated and washed with water. The dried organic solution was concentrated under water aspirator pres-sure to give 12.4 g of a colorless oil. This crude ~3g6~7 -2~-product was dissolved in 300 ml of diethyl ether and 120 ml of 1 N sodium hydroxide solution was added with ice cooling.
After stirring for 30 min., the organic layer was separated, washed with water and dried over magnesium sulfate. This diethyl ether solution was concentrated under water aspirator pressure to give 12.2 g of a colorless liquid. This crude material was chromato-graphed on 200 g of 60 to 80 mesh silica gel. Elution with n-hexane-ethyl acetate gave 11.7 g of the pure title compound (yield: 91.3~).
[~lD = ~4-4 (c 3.63 ETOH). Anal. Calcd.for C20H40O2 = ~,76.86%; H, 12.906.Found : C,77.14%;
H, 12.75%.IR v cm - 3,400. NMR (CDC13) ~: -0.87 (d, 6H, J=6 Hz) 1.30 (s, 3H) 2.20 (m, lH) 2.97 (d-d, lH) 3.48 - 4.00 (m, 2H). MS m/e = 294.
EX~MPLE 2 Synthesis of (2R, 3R)-epoxy-(3R, 7R, llR)-3, 7, 11, 15 - tetramethylhexadecane-l-ol (formula II) 5.7 g (20 mM) of titanium tetraisopropoxide, 4.2 g (20 mM) of D-(-)- diethyl tartrate 7 6 g (20 mM) of natural phytol and 40 mM of t-butyl hydroperoxide were reacted in the same manner as in Example 1 to afford 5.6 g of the title compound (yield: 89.7%).
[~]D5 = + 4 3 (c 2.8 ETOH) IR, NMR, Mass spectra were completely identical with the spectra obtained in Example 1.

Synthesis of (3S, 7R, llR) - 3, 7, 11, 15 - tetra-methylhexadecane-1,3-diol (formula III') ~2;~4~

To a solution of 0.75 g (20 mM) of lithil~ aluminum hydride in 100 ml of TE3F was added 20 ml of a THF solu-tion containing 6.24 g (20 mM~ of (2S, 3S)-epoxy-(3S, 7R, llR) - 3, 7, 11, 15 - tetramethylhexadecane-l-ol over a period of 30 min.
After stirring ~or 2 hours at 5C, the reaction mixture was treated in the usual manner to give 6.1 g of title compound (yield: 100%).

Found: C, 76.10%; H, 13.57%. IR ~ cm = 3400.
N~R (CDC13) ~ : 0.86 (d, 6H , J=6 Hz), 1.24 (s, 3E~) 2.40 (b-s, lH), 2.84 (b-s, lH) 3.65 -

4.00 (m, 2H) MS m/e : 296 Synthesis of (3R, 7R, llR) - 3, 7, 11, 15 - tetra-methylhexadecane-1,3-diol (formula III) 1.52 g ~40 ïnM) of lithium aluminum hydride and 2.48 g (40 mM) of (2R, 3R)-epoxy-~3S, 7R, llR)-3, 7, 11, 15-tetramethylhexadecane-l-ol were reacted in the same manner as in Example 3 to give 2.3 g (yield: 100%) of the title compound.
IR, NMR and Mass spectra were completely identical with the spectra obtained in Example 3.

Synthesis of (3S, 7R, llR) - 3, 7, 11, 15 -tetra-methyl-3-methoxymethyleneoxy-hexadecane-1-ol (formula IV') (i) ~ a solution of 6.3 g (20 mM) of (3S, 7R, llR)-3, 7, 11, 15 - tetramethylhexadecane-1,3-diol in 50 ml of pyridine was added 2.9 g of (24 mM) of pivaloyl ch]oride at 0C

.~L2,39fia~7 After stirring for 1 hour, the reaction mixture was poured into 200 ml of 5~ HCL solution. The organic layer was washed with water, then dried to give 7.7 g of crude material.
(ii) To the solution of 7.7 g of pivaloyl ester in 100 ml of dry dichloromethane,2.9 g (24 mM) of N,N-dimethyl aniline was added followed by addition of 1.9 g (24 mM) of methoxymethyl chloride.
After stirring for 4 hours at ambient temperature, the reaction mixture was poured into 100 ml of 5% HCL
solution. Work-up with diethyl ether in the usual manner gave 8.2 g of colorless oil.
This material was chromatographed on 150 g of 60 to 80 mesh silica gel. Elution with n-hexane and ethyl acetate afforded 8.0 g of the pure title compound (yield: 95%).
[~]D = + 2.13 (c 6.34 ETOH). Anal. Calcd.for C27H54O4; C,73.25%; H, 12.30 %,Found C, 73.86%; E~, 12.45%; IR v cm = 1745.NMR
(CDC13) ~ : 0.86 (d, 6H, J=6 Hz) 1.20 (s, 9H), 1.24 (s, 3H), 1.85 (t, 2H , J=7Hz), 3.37 (s, 3H), 4.16 (t, 2H, J=7Hz), 4.70 (s, 2H). MS m/e = 442.
(iii ) The solution of 8.0 g of the above compound pro- _ duced in (ii) in 20 ml of diethyl ether was added to a solution of 1.0 g of lithium aluminum hydride in 50 ml of die-thyl ether at 0C.
After stirring for 1 hour, the reaction mixture was chilled with an ice bath. Work-up with water and 15% NaoH solution in the usual manner gave 6.5 g of the title compound (yield: 95%).

~ 3~3647 [~]D =+1.8 (c 7.50 ETOH) H~12.93~; Found: C,73.36%; H, 13.28%.
IR v cm = 3,450.NMR (CDC13) ~ : 0.86 (d, 61~,J-6Hz), 1.28 (s, 3H), 2.80 (t, lH
, J = 5Hz), 3.28 (s, 3H), 3.78 (q7 2H, J = SHz), 4.72 (s, 2~
MS m/e = 358, 340, 327.
EXP~LE 6 Synthesis of (3R, 7R, llR) - 3, 7, 11, 15 -tetramethyl-3-methoxyrnethleneoxyhexadecane-1-ol (formula IV) 6.3 g (20 mM)-of (3R, 7R, llR) - 3, 7, 11, 15 -tetramethylhexadecane-1,3-diol was -treated in the same manner as in Example 5, (i), (ii) and (iii), to give 6.4 g (yield: 89.3%) of the title compound.
L~]D = - 1.8 (c 3.59 ETOH) IR, NMR and Mass spectra were completely identical with the spectra obtained in Example S.

Synthesis of (3S, 7R, llR) - 3, 7, 11, lS -tetramethyl-3-methoxymethyleneoxyhexadecane-1-al (formula V') To a solution of 3.6 g (10 mM) of (3S, 7R, llR) -3, 7, 11, lS - tetramethyl-3-methoxymethyleneoxy-hexadecane-l-ol in 50 ml of dichloromethane was added 6.4 g (30 mM) of PCC in small portions. The reaction was monitored by tlc.
After stirring for several hours at room tempera-ture, 50 ml of diethyl ether was added to the reaction mixture and filtered through 50 g of Florisil. The resulting filtrate was evaporated to afford 3.7 g of yellow oil. This crude material was chromatographed * a trade mark ~l23~7 on ;'0 g of 60 to 80 mesh silica gel. Elution with n-hexane and diethyl ether afforded 3.1 g of the color-less title compound (yield: 87.1~) [C~]D = + 6.66 ( c 2.1 ETOil) Anal. Calcd.for C22H44O3 : C, 74.10~; H, 12.44~;
Found: C.73.89~; ~3. 12.73%, IR v cm 1 = 1730.
NMR (CDC13) ~ : 0.86 (d, 6H), 1.32 (S7 3H), 2.52 (t7 2H), 3.36 (s, 3H), 4.72 (s, 2H), 9.80 - 9.97 (m, lH). MS m/e -- 356.

Synthesis of (3R, 7R, llR) - 3, 7, 11, 15 -tetramethyl-3-methoxymethyleneoxyhexadecane-1-al (formula V)

5.4 g (15 mM) of (3R, 7R, llR) - 3, 7, 11, 15 -tetramethyl-3-methoxymethyleneoxy hexadecane-l-ol and 9.6 g (45 mM) of PCC were reacted in the same manner as in Example 7 to give 4.8 g (yield: 89.7~) of the title compound [~]25 = _ 6.45 (c 2.17 ETOH) IR, NMR and Mass spectra were completely identical with the spectra obtained in Example 7.

Synthesis of 2-[(3'S, 7'R, ll'R) - 3', 7', 11', 15' - tetramethyl-3'-methoxymethyleneoxy-1'-hydroxy hexadecanyl] - 3, 5, 6 - trimethyl-l, 4-hydroquinone dimethoxymethyl ether (formula VII') To a solution of 0.24 g (10 mM) of magnesium in 20 ml of dry THF was added 1 or 2 drops of ethylene-dibromide for activation of the magnesium. To this 30 solution was added 3.19 g (10 mM) of 2-bromo-3, 5, 6-trimethyl-1,4-hydroquinone dimethoxymethyl ether in 10 ml of dry THF. After the addition was finished, the reaction mixture was refluxed for 2 hours.

:~239~47 To this Grignard reagent was aclded 15 ml of dry THF solution containing 2.85 g (8 mM) of (3S, 7R, llR)-3, 7, 11, 15 - tetramethyl-3-methoxymethyleneoxy hexa-decane-l-al. After stirring for 1 hour at reflux, the reaction mixture was poured in~o 100 ml of saturated NEI4Cl solution.
Work--up with diethyl ether in the usual manner gave 5.5 g of pale yellow oil.
This crude material was chromatographed on 100 g of 60 to 80 mesh silica gel. Elution with n-hexane and diethyl ether afforded 3.8 g of the colorless title compound (yield: 79.7%).
[a]D = -4.58 (c 2.4 ETOH) Anal. Calcd.for C35H64O7 : C, 70.43%; H, 10.81%, Found: C, 70.30%; H, 11.01%; IR v cm = 3500.
NMR (CDC13) ~ : 0.86 (d, 6H , J = 7Hz), 2.18 (s, 3EI), 2.20 (s, 3E~), 2.42 (d, 3H, J =
2 Hz), 3.40 (s, 3~1), 3.63 (s, 6H), 3.76 - 3.96 (m, lH),4.75 (d, 2H,J = 2 Hz), 4.86 (s, 2H), 4.96 (s, 2H), 5.28 ~ 5.57 (m, lH).MS m/e=596.

Synthesis of 2 - [(3'R, 7'R, ll'R) - 3', 7', 11', 15'- tetramethyl-3'-methoxymethyleneoxy-l' hydroxy hexadecanyl] -3, 5, 6-trimethyl-1,4-hydroquinone dimethoxymethyl ether (formula VII) 0.12 g (5 mM) of magnesium, 1.6 g (5 m~) of 2-bromo-3, 5, 6-trimethyl-1,4-hydroquinone dimethoxymethyl ether and 1.4 g (4 mM) of (3R, 7R, llR) - 3, 7, 11, 15 -tetramethyl-3-me-thoxymethyleneoxyhexadecane-1-al were reacted according to Example 9 to give 1.8 g (yield:
75.6%) of the colorless title compound.

3~

[ ]25= + 5 87 (c 5.14 ETOH) IR, NMR and Mass spectra were completely identical with the spectra obtained in Example 9.

Synthesis of 2-[(3'S, 7'R, ll'R) - 3', 7', 11', 15' - tetramethyl-3l-methoxymethyleneoxy-ll-hexadecenylJ
-3, 5, 6-trimethyl-1,4-hydroquinone dimethoxymethyl ether (forrnula VIII') To a solution of 1.8 g (3 m~l) of 2-[(3'S, 7'R, ll'R)-3', 7', 11', 15' - tetramethyl-3'-rmethoxymethylene-oxy-l'-hydroxy hexadecanyl] - 3,5,6-trimethyl -1, 4-hydroquinone dirnethoxymethyl ether in 50 ml of ether were added successively 3 ml of pyridine and 1.0 g (8.4 mM) of thionyl chloride at 0C.
After stirring for 30 min., the reaction mixture was poured into 50 rnl of 5% HCl solution. Work-up with diethyl ether in the usual manner gave 1.9 g of crude product material.
The product did not S}IOW hydroxyl absorption in its IR spectrum.
1.9 g. of this crude material were dissolved in 30 ml of dry DMSO, and then treated with 2 g of DBN
at 100C.
After stirring for 30 min., the reaction mixture was poured into 100 ml of ice water. Work-up with diethyl ether in the usual manner gave 1.8 g of pale yellow oil. This material was chromatographed on 50 g of silica gel. Elution with n-hexane and ether af-forded 1.5 g of the colorless title compound (yield:
86.4%) [~]D = ~ 10.08~ (c 7.8 ETOH) H, 10.80~, Found: C, 72.98~; H, 11.07%.

- :123'~6~7 NMR (CDC13) ~ : 0.87 (d, 6H , J - 7 Hz), 1.44 (s, 3H), 2.23 (s, 6H) 2.27 (s, 3H), 3.40 (s, 311) 3.57 (s, 3H),3.63 (s, 3H), 4.75 (q, 2H, J= 6Hz), 4.85 (s, 2H~, 4.90 (s, 2H), 5.90 (d, lH, J=17 Hz), 6.52 (d, lH, J = 17 Hz). MS m/e = 578.

Synthesis of 2-[(3'R, 7'R, ll'R) - 3', 7', 11', 15'-tetramethyl-3'-methoxymethyleneoxy-1'-hexadecenyl]
-3, 5, 6-trimethyl-1,4-hydroquinone dimethoxymethyl ether (formula VIII) 1.2 g (2 m~l) of 2-[(3'R, 7'R, ll'R)-3', 7', 11', 15'-tetramethyl-3'-methoxymethyleneoxy-1'-hydroxy hexadecanyl]-3, 5, 6-trimethyl-1,4-hydroquinone di-methoxymethyl ether, 0.67 g (5.6 mM) of thionyl chloride and 1.3 g of DBN were reacted according to Example 11 to give 0.9 g (yield: 77.8%) of the title compound.
[~]D = + 11.81 (c 2.07 ETOH) IR, NMR and Mass spectra were completely identical with the spectra obtained in Example 11.

Synthesis of 2-[(3'S, 7'R, ll'R) - 3', 7', 11', 15' - tetramethyl-3'-methoxymethyleneoxy hexadecanyl~ - 3, 5,

6 - trimethyl-1,4-hydroquinone dimethoxyme-thyl ether -~
(formula (IX') 1.5 g (2.6 n~l) of 2-[(3'S, 7'R, ll'R) - 3', 7', 11', 15' - tetramethyl-3'-methoxymethyleneoxy-1'-hexa-decenyl]-3, 5, 6-trimethyl-1, 4-hydroquinone dimethoxy-methyl ether was dissolved in 50 ml of ethanol contain-ing 500 mg of 5% palladium-charcoal. The resulting mix-ture was vigorously stirred under a hydrogen pressure il~3~4~

of one atmosphere at room temperature.
After stirring for 2 hours, the reaction mixture was filtered. The filtrate was concentrated under aspirator pressure to give 1.45 g of the colorless title compound (yield: 100~) [~]D = -4.58 (c 3.5 ETOH) . . C35H60O6 : C, 72.87~;H, 10.48~;Found: C, 73.15%;H, 10.65%. NMR
(CDC13) ~ : 0.87 (d, 6~, J=6Hz), 2.20 (s, 6H), 2.25 (s, 3H), 2.52 - 2.84 (m, 2H), 3.40 (s, 3H), 3.62 (s, 6H), 4.76 (s, 2H), 4.88 (s, 2H) 4.89 (s, 2H). MS m/e = 576 Synthesis of 2-[(3'P~, 7'R, ll'R) - 3', 7', 11', 15' - tetramethyl-3'-methoxymethyleneoxy hexadecanyl]
- 3, 5, 6 - trimethyl - 1,4 - hydroquinone dimethoxy-methyl ether (formula IX) 1.06 g (2 m~l) of 2-[(3'R, 7'R, ll'R) - 3', 7', 11', 15' - tetramethyl-3'-methoxymethyleneoxy-1'-hexadecenyl] -3, 5, 6-trimethyl-1, 4-hydroquinone dimethoxymethyl ether and 0.3 g of 5% palladium-charcoal were reacted according to Example 13 to give 1.04 g of the colorless title compound.
[ ]25 = + 5 02 ( c 4.8 ETOH) IR~, NMR and Mass spectra were completely identical with the spectra obtained in Example 13.
EX~MPLE 15 Synthesis of 2-[(3'S, 7'R, ll'R) - 3', 7', 11', 15'-tetramethyl-3'-hydroxyhexadecanyl] -3, 5, 6-trimethyl-1,4-benzoquinone, also called (alpha-(3'S) -tocopheryl quinone) (formula X') :3~239~7 (i) To a solution of 1.45 g (2.5 I~M) of 2-~(3'S, 7'R, ll'R) -3', 7', 11', 15' - tetramethyl-3'-methoxy-methyleneoxy hexadecanyl] - 3, 5, 6 - trimethyl - 1,4 -hydroquinone dimethoY.ymethyl ether in 20 ml of THF
was added 20 ml of ln~ HCl solution. After stirring for 1 hour at roorn temperature, the reaction mixture was diluted with 50 ml of water. This solution was extracted with diethyl ether twice. To the combined ether solutions was added 2 g of lead dioxide at room temperature.
After stirring for 1 hour, the reaction mixture was filtered and the filtrate was concentrated under water aspirator pressure to give 1.4 g of pale yellow .
oil. This material was chromatographed on 30 g of silica gel. Elution with n-hexane and ether afforded 1.1 g Iyield: 89.6%~ of pale yellow alpha-(3'S)-methoxymethyl tocopheryl quinone.
[~]25 = _ 3.27 (c 1.69 ETOH) Anal.Calcd. for C31H54O4 : C, 75.87%, H, 11.09~, Found: C, 76.18%; H, 11.36~. IR
v cm = 1640. N~R (CDC13) ~ : 0.87 (d, 6H
, J = 6 Hz), 2.02 (st 6H), 2.04 (s, 3H), 2.36 - 2.62 (m, 2~1), 3.40 (s, 3H), 4.75 (s, 2H).
MS m/e = 429.
(ii) To a solution of 1.1 g (2~2 I~M) of alpha-(3'S)-methoxymethyl tocopheryl quinone in 30 ml of methanol was added 20 ml of 10~ HCl solution.
After stirring for 5 hours at room temperature, 50 ml of water was added. This solution was extracted with 50 ml of diethyl ether twice. The combined ether solutions were concentrated under wa-ter aspirator ~2;39~47 pressure to give 7.7 g of pale red oil.
This material was chromatographed on 25 g of silica gel. Elution with n-hexane and diethyl ether afforded 0.9 g (yield: 89%) of the pale red title compound.
[ ]25 = + 1 08 (c 10.6 EIOH) 29 50 3 , 7 .97~1 H, 11. 8%.
Found: C, 78.15%; H, 11.41%; IR v cm 3450, 1640. NMR (CDC13) ~ : 0.87 (d, 6H, J =

7 Hz), 1.24 (s, 3H), 2.0G (s, 6H), 2.03 (s, 3H), 2.4a - 2.70 (m, 2H). MS m/e = 428.
E ~AMP LE 16 Synthesis o. 2-[(3'R, 7'R, ll'R) - 3', 7', 11', 15' - tetramethyl-3'-hydroxy hexadecanyl] -3, 5, 6 -trimethyl-1,4-benzoquinone, also called (alpha-(3'R) -tocopheryl quinone) (formula X) (i) 1 g (1.7 mM) of 2-~(3'R, 7'R, ll'R) - 3', 7', 11', 15' - tetramethyl-3'-methoxymethyleneoxy hexadecanyl]
-3, 5, 6 - trimethyl-l, 4 - hydroquinone dimethoxy-methyl ether, 15 ml of 10~ HCl solution and 1.5 g of lead dioxide were reacted according to Example 15(i) to give 0.75 g (yield: 89.9%) of pale yellow alpha-(3'R)-methoxymethyl tocopheryl quinone.
[ ]25 = + 3 8 (c 4.39 ETOH) IR, NMR and Mass spectra were completely identical with the spectra obtained in Example 15.
(ii) 0.75 g (1.5 mM) of alpha-(3'Rj-methoxymethyl tocopheryl quinone and 15 ml of 10% HCl solution were reacted according to Example ]5 (ii) to give 0.6 g (yield: 89.5~) of thepale redtitle compound.

~3~6~
-33~

[~]D5 = -1.01 (c 18.8 ETOH) IR, NMR and Mass spectra were completely identi-cal with the spectra obtained in Example 15.

Synthesis of (2S, ~'R, 8'R) - alpha-tocopherol (formula XI') 1 g (4 mM) of d-camphor sulfonic acid was added to a solution of 0.9 g (2 mM) of 2-[(3'S, 7'R, ll'R) -3', 7', 11', 15' - tetramethyl-3'-hydroxy hexadecanyl]
-3, 5, 6 - trimethyl-1,4-benzoquinone in 20 ml of meth-anol. After stirring for 15 min. at room temperature, the mixture was poured into 50 ml of ice water.
Work-up in the usual manner (extraction with diethyl ether 2 times, and drying over magnesium sulfate) afforded 0.85 g of pale yellow oil.
This material was chromatographed on 30 g of silica gel. Elution with n-hexane and diethyl ether afforded 0.8 g (yield: 93%) of colorless title com-pound.
[~]25 = + 0.85 (c 1.15, benzene) K3Fe(CN)6 oxidation product:
[~]D = ~ 29.6 (c 1.70, isooctane) This (2S, 4'R, 8'R)-alpha-toCopheryl quinone was ~.
acetylated with acetic anhydride and pyridine to give (2S, 4'R, 8'R)-alpha-tocopheryl acetate in quantitative yield.
[~]D = -2.25 (c 1.1 ETOH) Synthesis of (2R, 4'R, 8'R) - alpha-tocopherol (formula XI) 123964~

0.65 g (2.6 mM) of d-camphor sulfonic acid and 0.6 g (1.3 mM) of 2-[(3'R, 7'R, ll'R) - 3', 7', 11', 15' - tetramethyl-3'-hydroxy hexadecanyl] - 3,5,6 - tri-methyl - 1,4 - benzoquinorle were reacted according to Example 17 to give 0.52 g of the colorless title compound (yield: 90.3~) [~]D = ~ 2.76 (c 1.07, benzene) UV ~ max = 292 nm; ~ c1% = 69.7 K3Fe(CN)6 oxidation product:
[~]D = + 29.8 (c 1.05 isooctane) Acetate (formed according to Example 17):
[ ]25=+ 3 49o (c 1.1 ETOH)

Claims (8)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for preparing an optically active compound of the formula IX

wherein E is , and R1, R2 and R3 are protecting groups for hydroxyl functions which comprises catalytically hydrogenating the double bond in the aliphatic chain of a compound of formula VIII

wherein E is , and R1, R2 and R3 are protecting groups for hydroxyl functions.

2. A process according to claim 1, wherein said catalytically hydro-genation is carried out at a temperature of from about 0°C to about 80°C in a solvent.

3. A process according to claim 1 wherein the compound of formula VIII

is firstly prepared by the dehydration of a compound of formula VII

wherein E is , and R1, R2 and R3 are protecting groups for hydroxyl functions in inert solvent.

4. A process according to claim 1, 2 or 3 further comprising the step of converting the compound of formula IX to a compound of formula X

wherein Q is and R1 is a protecting group for a hydroxyl function by removal of all of the protecting groups R1, R2 and R3 following by oxidation.

5. An optically active compound of the formula wherein E is , and R1, R2 and R3 are protecting groups for hydroxyl functions.

6. A compound according to claim 5, wherein R1, R2 and R3 are the same or different and are each a hydroxy protecting group which reacts only with a tertiary alcohol and is selected from the group consisting of alkyl, alkoxyalkyl, aryl and aralkyl groups.

7. A compound according to claim 6, wherein R1 is methoxymethylene.

8. A compound according to claim 6 or 7, wherein R2 and R3 are each methoxymethylene.