Tetrahedron Vol. 38, No. 17, pp. 2627 to 2633, 1982 0040.-4020~82[172627.-07503.00~ Printed in Great Britain. 19~2 Pergamon Press Ltd.

A NOVEL TOTAL SYNTHESIS OF ELAEOCARPUS ALKALOIDS

HIROTAKA OTOMASU, NORIYUKI TAKATSU, TOSHIO HONDA

and

TETSUJI KAMETANI

Hoshi Col lege of Pharmacy Ebara 2-4-41, Shinagawa-ku, Tokyo 142, Japan

(Received in Japan 5 June 1982)

b e . - - - - ~ The novel synthesis of e laeocarpus alkaloids has en acnlevea employing 1,3-dipolar cycloaddit ion reaction as a key step.

Elaeocarpus alkaloids, such as elaeo-

kanine A(~), B(~) and C(~), isolated from

the leaves of Elaeocarpus kaniensis by

Johns and his co-workers I , are known to

possess a character ist ic trans- indo-

l iz idine r ing system. These alkaloids

can be der ived from appropriate condensa-

tion of ornithine and a Cs-polyket ide,

and a biosynthet ic scheme for the deri-

vat ion of these alkaloids has been shown 1

in scheme I.

We have planned to synthesize these

alkaloids along with the above biosynthe-

tic pathway. For this purpose, the 1,3-

dipolar cycloaddit ion react ion of A l-

pyrrol in- l -oxide, which might serve as

a chemical equivalent of ornithine, wi th

an appropriate e ight-carbons dipolarophi le

has been investigated. With regard to

the synthesis of these alkaloids, many

papers 2-9 have appeared to date. In

fact, the synthesis of e laeokanine C

employing 1,3-dipolar cycloaddit ion re-

action has or ig inal ly been achieved by

Tufar iel lo 5 who however has used A l-

pyrrolin-l-oxide and pent- l -ene as start-

ing mater ials and the C 5 - C 7 carbons

have been introduced at the later stage.

O i 2

H,,.. 3

6

'O

HO O

H

O

Scheme 1

2627

2628 H. OTOMASU et al.

_ .~~OTHP

Our requisite enone as a dipolarophile,

which would be a substitute of Cs-poly-

ketide was prepared as follows. Butyn-

i-oi tetrahydropyranyl ether (~) was

OH

OTHP

Scheme 2

The trans-enone (~) was obtained by

treatment of the alcohol (~) with man-

ganese dioxide in petroleum ether in 70

% yield. Whereas the cis-enone (~) was

prepared by catalytic reduction of ~ on

pal ladium sulfate II and subsequent oxi-

dation of the olefin (~) with manganese

dioxide, in 48 % yield from ~.

Since the both enones (~ and ~) could

be synthesized stereoselectively, the

cycloaddit ion with Al-pyrrol in- l -oxide

(~) was then investigated. Based on the

mechanist ic aspects, the trans-enone would

be an appropriate dipolarophi le to synthe-

size elaeokanine C, stereoselectively.

Thus, 1,3-dipolar cycloaddit ion of ~ with

~ was carried out in chloroform to afford

the adduct (~) as inseparab%e stereoiso-

meric mixtures at the C3-posit ion of the

isoxazol idine ring, in 91% yield, whose

deprotect ion of tetrahydropyranyl ether

with 1N hydrochloric acid in t~trahydro-

furan gave the primary alcohol (~a and

~b) . The ratio of ~a : 12b was deter-

mined to be 2 : 3 based o~ its NMR data

[6 4.06 (2/5H, dt, J = 6 and 8 Hz, 3e-H)

and 3.97 (3/5H, dt, J = 8 and 8 Hz, 37-

H)], and this ratio was consistent with

those reported 12 Diff icult ies were

init ial ly encountered in the convers ion

treated with n-butyraldehyde in the pre-

sence of n-butyl l i thium to afford the

acetylenic alcohol (~), whose reduction

with l ithium aluminum hydride I0 in tetra-

hydrofuran gave the trans-olef in (~) in

69 % yield from ~.

OH O

OTHP ~ OTHP

OH O

OTHP OTHP

of ~ tO 4' e.g. attempted reductive N-O

bond cleavage with Raney-nickel, palladi-

um-carbon and zinc powder, followed by

selective mesylat ion of the primary alco-

hol afforded none of the desired product

but complicated mixtures, and mesylation

of ~ with methanesulfonyl chloride and

tr iethylamine in methylene chloride again

gave rise to the decomposed product.

Whereas, treatment of ~ with methane-

sulfonyl chloride in pyridine gave the

quaternary salt (~) , which without iso-

lation was treated with zinc powder in 50

% aqueous acetic acid to yield the B-

hydroxy ketone (~) as a major product and

a trace amount of elaeokanine A, probably

arising from elaeokanine C by dehydration.

The stereochemistry of the S-hydroxy

ketone was assigned to be ~ on the basis

of its spectral data and the formation of

~ suggested that the epimerization at

the C4-posit ion of the isoxaz~idine (~b)

occurred during its conversion into 14

as shown in Scheme 4.

In order to confirm this observation,

the cis-enone (~) was treated with ~ to

furnish the adduct (~) , which was clear-

ly different from ~. After the depro-

tection of tetrahydropyranyl ether with

1N hydrochloric acid, the result ing

A noveltomlsyn~esisofelaeocardusal~loids

primary alcohol (~) was converted to the

quaternary salt with methanesulfonyl

chloride. Reduction of the salt with zinc

powder afforded the B-hydroxy ketone (~) ,

in 25.8 % yield, which was identical with

~he authentic sample obtained from the

trans-enone (~) as above. Though the

stereoselect ive synthesis of elaeokanine

2629

C has not been successful, ~ was oxidi-

zed to the diketone (~) with dimethyl

sulfoxide and dicyclohexylcarbodi imide 13

or with Jones reagent. Since the conver-

sion of ~ to elaeokanine B(~) and C(~)

has already been reported, this synthesis

constitutes a formal total synthesis of

elaeokanine alkaloids.

O

OR OTHP

%Ms

o /

HO H

"~ ~ n r--~

0

OTHP

0

~ R=THP

Scheme 3

2630 H. OTOMASU et al.

]"" "" I

OH

~a 3 .L

-H20 >

H,,,

O

12b

.>

Scheme 4

EXPERIMENTAL

IR spectra were measured w i th a 215

H i tach i Grat ing in f rared spect rophoto -

meter and were ca l ib ra ted wi th the 1610 -I cm absorpt ion of po lys tyrene . IH-NMR

spectra were obta ined on a JEOL JNM-FX I00

spect rometer us ing te t ramethy ls i lane as

an interna l re ference. Mass spectra were

taken w i th a JEOL JMS-D300 spectrometer .

3 -Octyne- l ,5 -d io l l - te t rahydropyrany l

e ther (5). To a s t i r red so lu t ion of 3-

butyn- l -o l te t rahydropyrany l e ther (11.5

g, 74.6 mmol) in te t rahydro furan (50 ml)

was added a so lu t ion of n -buty l l i th ium

(15 % w/v in hexane; 57.3 ml, 89.5 mmol)

at -78C over the per iod of 2 hr. A f te r

s t i r r ing for 0.5 hr, n -butyra ldehyde

(6.45 g, 89.5 mmol) was added and the

resu l t ing mixture was s t i r red at -78C

for 1.5 hr and was then a l lowed to warm

to 0C. Water (50 ml) was added and the

phases were then separated. The aqueous

phase was ext rac ted wi th ether (2 x 30 ml).

H

III

H

19

The organ ic phases were combined, washed

w i th saturated aq sod ium ch lor ide , dr ied,

and concent ra ted to give a ye l low ish oi l ,

wh ich was chromatographed on s i l ica gel

(400 g) e lu t ing wi th CH2CI2 -MeOH (19 : i)

to give ~ as a co lo r less o i l (16.5 g,

97.6 %) : IR (film) cm -I 3430 (broad),

2960, 2880, 1030; NMR (CDCI 3) ,% 0.94

(3H, t, J = 7 Hz), 2.51 (2H, dt, J = 2

and 7 Hz), 2.68 (IH, br s), 3.42 - 3.65

(2H, m), 3.69 - 3.93 (2H, m), 4.34 (IH,

br s), 4.64 (IH, m); MS (m/e) 227 (M + +

1), 209, 137, 107, 85. Calc for

C13H2203 : C, 68.99; H, 9.80. Found: C,

68.91; H, 9.92 %.

3 (E) -Octene- l ,5 -d io l ] - te t rahydropyrany l

e ther (4). To a s t i r red suspens ion of

l i th ium a luminum hydr ide (4.28 g, 113

mmol) in ether (200 ml) was added a solu-

t ion of ~ (21.3 g, 94 mmol) in ether (30

ml) at room temperature . A f ter s t i r r ing

for 4 hr at ambient temperature under an

a tmosphere of n i t rogen, the react ion was

quenched by the add i t ion of water (20 ml).

A novel~talsy~hesisofel~oc~dusalkMoids 2631

The inso lub le mater ia l formed was f i l ter - aq sod ium chlor ide, dr ied, and concent -

ed off and washed w i th ether (5 x 39 ml). rated to give a res idue, wh ich was sub-

The combined f i l t rate was evaporated to jected to co lumn chromatography on s i l i ca

give a res idue, wh ich was chromatographed gel (100 g). E lu t ion w i th CH2Cl2 -acetone

on s i l i ca gel (500 g) e lu t ing w i th CH2CI 2- (19 : i) a f fo rded ~ as a co lo r less oi l

acetone (19 : I) to a f fo rd ~ as a co lor - (2.76 g, 68.3 %) : IR (film) cm -I 3450

less oi l (15.3 g, 71 .1%) : IR (film) cm -I

3445 (broad), 2940, 2870, 1030, 970; NMR

(CDCI 3) 6 0.93 (3H, m), 1.78 (IH, br s),

2.34 (2H, dr, J = 6 and 6.5 Hz), 3.30 -

4.20 (5H, m), 4.58 (IH, br m), 5.30 -

5.67 (2H, m); MS (m/e) 211 (M+-OH), 127,

109, I01, 85. Calc for C13H2403 : C,

68.38; H, 10.59. Found: C, 68.59; H

10.93 %.

5 -Oxo-3(E) -oc ten- l -o l te t rahydropyran~l

ether (~). To a s t i r red suspens ion of

manganese d iox ide (20.3 g) in pet ro leum

ether (150 ml) was added 6 (2.5 g, 10.9

mmol) and the mix ture was fur ther s t i r red

at ambient temperature for 1 hr. A f te r

removal of an inso lub le mater ia l by f i l t -

rat ion, the f i l t rate was concent ra ted to

the res idue, wh ich was chromatographed

on s i l i ca gel e lu t ing w i th CH2Cl2 -acetone

(97 : 3) to y ie ld the enone ~ as a co lor -

(broad), 2955, 2870, 1033; NMR (CDCI 3)

6 0.94 (3H, t, J = 7 Hz), 2.10 - 2.80

(3H, m), 3.24 - 3.63 (2H, m), 3.68 - 3.96

(2H, m), 4.40 (IH, dt, J = 6.5 and 6.5

Hz), 4.60 (IH, br m), 5.16 - 5.69 (2H,

m); MS (m/e) 211 (M+-OH), 127, 109, i01,

85. Calc for C13H2403 : C, 68.38; H,

10.59. Found: C, 68.09; H, 10.85 %.

5-Oxo-3(Z)-Octen-l-ol te t rahydropyrany l

ether (~). The ox idat ion of ~ (4.30 g,

18.8 mmol) w i th manganese d iox ide (40 g)

in pet ro leum ether (150 ml) was car r ied

out as descr ibed for ~ to g ive ~ as a

co lo r less oi l (2.78 g, 70.2 %) : IR (film) -i cm 2950, 2875, 1693, 1620, 1032, 985;

NMR (CDCI 3) 6 0.93 (3H, t, J = 7 Hz),

2.44 (2H, t, J = 7 Hz), 2.93 (2H, ddd,

J = 5, 6 and 6.5 Hz), 3.39 - 3.61 (2H, m)

3.71 - 3.94 (2H, m), 4.59 (IH, br m),

6.03 - 6.34 (2H, m) ; MS (m/e) 227 (M + +

less o i l (1.74 g, 70.2 %) : IR (film) cm -I i), 209, 153, 125, 85. Calc for C13H2203

2950, 2875, 1680; NMR (CDCI3) 6 0.94 (3H,

t, J = 7 Hz), 2.51 (2H, dtt, J = 1.4, 6.5

and 6.5 Hz), 2.52 (2H, t, J = 7.5 Hz),

3.41 - 3.64 (2H, m), 3.76 - 3.99 (2H, m),

4.59 (IH, br m), 6.17 (IH, dt, J = 1.4

and 16 Hz), 6.84 (IH, dt, J = 7 and 16

Hz); MS (m/e) 227 (M + + i), 153, 125, 85.

Ca lc for C13H2203 : C, 68.99; H, 9.80.

Found: C, 68.61; H, 10.04 %.

3 (Z) -Octene- l ,5 -d io l l - te t rahydropyrany l

e ther (~). A mix ture of ~ (4.0 g, 17.7

mmol) , PdSO4~H20 (400 mg) and pyr id ine

(20 ml) was shaken at ambient temperature

under an a tmosphere of hydrogen. A f ter

an absorpt ion of hydrogen (397 ml, 17.7

: C, 68.99; H, 9.80. Found: C, 68.84;

H, 9.99 %.

1 ,3 -D ipo lar cyc loadd i t ion o f ~ : Forma-

t ion of the i soxazo l id ine (~) . A solu-

t ion of ~ (I.Ii g, 4.90 mmol) and Al -py -

r ro l in - l -ox ide (0.84 g, 9.88 mmol) in

to luene (15 ml) was re f luxed at ambient

temperature in a cur rent of n i t rogen for

3 hr. A f ter evaporat ion of the solvent,

the res idue was chromatographed on s i l i ca

gel (100 g) e lu t ing w i th CH2Cl2 -acetone

(17 : 3) to a f ford the i soxazo l id ine (~)

as s te reo isomer ic mixtures at the C3-pos i -

t ion ( i soxazo l id ine number ing) (1.39 g,

91.0 %) : IR (film) cm -I 2950, 2850, 1710,

mmol) had ceased, the cata lys t was f i l ter - 1033; NMR (CDCI 3) t 0.93 (3H, t, J = 7

ed off and was washed w i th benzene (3 x

10 ml). The combined f i l t rate was con-

cent ra ted to the res idue, wh ich was re-

d i sso lved in benzene (50 ml). The org-

anic layer was washed wi th saturated aq

potass ium hydrogen sul fate and saturated

Hz), 2.41 (2H, t, J = 7 Hz), 3.14 (2H, t,

J = 6.5 Hz), 3.31 - 3.65 (3H, m), 3.73 -

3.98 (3H, m), 4.43 (IH, dt, J = 6 and

8.5 Hz) , 4.56 (IH, br m) ; MS (m/e) 312

(M+ + I), 311 (M+), 310, 228, 152, 86,

85.

2632

Deprotect ion o_~f te t rahydropyrany l e ther

o__[f ~ . To a s t i r red so lu t ion of 1~ (500

mg, 1.61 mmol) in te t rahydro furan (7 ml)

was added IN HCl (4.5 ml) at ambient

temperature . A f te r the s t i r r ing had

been cont inued for 5 hr, the so lut ion

was bas i f ied w i th sod ium carbonate and

ext rac ted wi th e ther (3 x I0 ml). The

organ ic layer was washed w i th satura-

ted aq sod ium ch lor ide , dr ied, and con-

cent ra ted to g ive the res idue , wh ich was

sub jec ted to co lumn chromatography on

s i l i ca gel (25 g). E lu t ion wi th CH2CI 2-

MeOH (9 : i) a f fo rded the a lcoho l (~)

as a ye l low ish gum (270 mg, 74.0 %) : IR

H. OToMAsuetal.

3390 (broad), 2970, 2880, 1710, 1055;

NMR (CDCI3) 6 0.94 (3H, t, J = 7.5 Hz),

2.40 - 2.60 (2H, m), 2.91 (IH, br s),

2.80 - 3.40 (3H, m), 3.50 - 3.80 (2.5H,

m), 3.90 - 4.20 (IH, m), 4.50 (0.5 H, dt,

J = 5.5 and 8.5 Hz); m/e 227.1537 (calc for

C I2H21NO3, 227.1520) .

7 -Ep ie laeokan ine C (~4) and e laeokan ine

A (I). A mix ture of 12 (2.0 g, 8.80

mmol) , methanesu l fony l ch lo r ide (3.02 g,

26.4 mmol) and pyr id ine (44 ml) was a l low-

ed to stand at room temperature for 5 hr.

A f te r evaporat ion of the solvent , the

res idue was d i sso lved into 50 % aq ace-

(film) cm -I 3410 (broad), 2975, 2885, 1710, t ic ac id (44 ml).

1058; .NMR (CDCI3) ~ 0.94 (3H, t, J = 7

Hz), 2.43 (2H, t, J = 7.5 Hz), 3.16 (2H,

m), 3.56 (3/5H, dd, J = 8 and 8 Hz), 3.71

(2H, t, J = 6 Hz), 3.76 (2/5H, dt, J =

6 and 8 Hz), 3.97 (3/5H, dt, J = 8 and 8

Hz), 4.06 (2/5H, dt, J = 6 and 8 Hz),

4.50 (IH, dt, J = 6 and 8 Hz) ; MS (m/e)

227 (M+), 154, 143, 138, 128, 125, 112,

110, 86, 85; m/e 227.1509 (calc for

C I2H21NO 3, 227.1520) .

1 ,3 -D ipo la r cyc loadd i t ion of ~ : Forma-

t ion of the i soxazo l id ine (~) . A so lu-

t ion of ~ (2.50 g, I i .0 mmol) and Al -py -

r ro l in - l -ox ide (I{88 g, 22.1 mmol) in

ch lo ro form (30 ml) was s t i r red at ambient

temperature in a cur rent of n i t rogen for

3 days and then heated under re f lux for

14 hr. A f te r evaporat ion of the solvent ,

the res idue was chromatographed on

s i l i ca gel e lu t ing w i th CH2Cl2 -acetone

(17 : 3) to g ive the addHct (15) as a

co lo r less gum (3.11 g, 90.4 %) : IR (film) -1

cm 2950, 2875, 1710, 1033; NMR (CDCI3)

0.93 (3H, t, J = 7 Hz), 2.30 - 2.60

(3H, m), 3.15 (2H, m), 3.48 (2H, m),

3.70 - 4.20 (3H, m) , 4.42 (IH, dt, J = 6

and 9 Hz), 4.54 (IH, m) ; MS (m/e) 312 (M +

+ i) , 311, 3]0, 228, 210, 154, 86, 85.

To the above s t i r red

so lu t ion was added zinc powder (8.63 g,

132 mmol) at 50C and the s t i r r ing was

cont inued for 1.5 hr at the same temper -

ature. The resu l t ing so lut ion was cool -

ed to 0C, d i lu ted wi th water (30 ml) and

bas i f ied w i th Na2CO 3 to pH 9. A f ter re-

mova l of the inso lub le mater ia l by f i l t -

rat ion, the f i l t rate was ext rac ted w i th

methy lene ch lo r ide (3 x 40 ml). The org-

anic laye'r was washed w i th saturated aq

sod ium ch lor ide , dr ied and evaporated to

give the res idue, wh ich was sub jected to

co lumn chromatography on s i l i ca gel (80

g). E lu t ion wi th CH2CI2 -MeOH (17 : 3)

a f fo rded 7 -ep ie laeokan ine C (14) as a

co lo r less gum (309 mg, 16.6 %) : IR (

CHCI 3) cm -I 3420 (broad), 2933, 2807,

2480, 1705, 1375; NMR (CDCI3) $ 0.91 (

3H, t, J = 7 Hz), 1.60 (2H, tq J = 7 and

7 Hz), 2.54 (2H, t, J = 7 Hz), 2.55 (IH,

dd, J = I0 and I0 Hz), 2.80 - 3.30 (3H,

m) , 3.87 (IH, dt, J = 5 and 10 Hz) ; MS

(m/e) 211 (M+) , 194, 182, 167, 152, 140,

124, 97; m/e 211.1583 (calc for C I2H21NO2,

211.1573). 14 was c rys ta l l i zed as its

p icrate , m.p. 160 - 161.5C (from ethanol ) ,

ca lc for C I8H24N409 : C, 49.09; H, 5.49;

N, 12.72. Found: C, 49.00; H, 5.61; N,

12.56 %.

Deprotect ion of te t rahydropyrany l ether

of 15. Deprotect ion of te t rahydropyra -

nyl e ther of 15 (2.00 g, 6.42 mmol) w i th

I N HCl (15 ml) in te t rahydro furan (80

ml) was car r ied out as descr ibed above

to g ive the a lcoho l (3~6) as a ye l low ish

gum (1.05 g, 71.6 %) : IR (film) cm -I

Fur ther e lu t ion w i th CH2CI2 -MeOH (17 : 3)

gave e laeokan ine A (2 mg, 0.I %), whose

spectra l data were cons is tent w i th those

of repor ted one I.

The convers ion of J~ into ~4. The con-

vers ion of ~ (300 mg, 1.32 mmol) was

A noveltotalsynthesisofelaeoc~dusalk~oids

carr ied out as above by mesylat ion with

methanesul fonyl chloride (455 mg, 3.97

mmol) and a subsequent reduction with

zinc powder (1.15 g, 17.6 mmol) in 50 %

aq acetic acid (6.6 ml) to afford 14

(72 mg, 25.8 %), which was identical with

the authentic sample obtained above.

The oxidat ion of ~ into 15 with Moffatt

reagent. To a solution of ~ (150 mg,

0.71 mmol) in benzene (5 ml) and dimethyl-

sulfoxide (5 ml) containing pyridine (60

mg, 0.76 mmol) and tr i f luoroacet ic acid

(40 mg, 0.35 mmol), was added dicyclo-

hexylcarbodi imide (580 mg, 2.81 mmol)

and the result inq mixture was stirred at

ambient temperature for 15 hr. After

evaporat ion of the solvent, the residue

was di luted with water (30 ml) and basi-

f ied with sodium carbonate to pH ii.

Carbon tetrachlor ide (20 ml) was added

into the above mixture and the precipitate

was removed off by fi ltration. The com-

bined f i ltrate and washings were washed

with water, dried, and evaporated to give

the residue which was subjected to column

chromatography on sil ica gel (12 g).

E lut ion with CH2CI2-MeOH (9 : i) afforded

2633

Acknowledgements - - We thank Mrs. T. Ogata,

Miss M. Shigetsuna, Miss M. Nagao, Mrs.

A. Kumazawa, Miss H. Furuyama, and Miss

Y. Narita of Hoshi Col lege of Pharmacy

for spectral measurements, microanalyses,

and manuscr ipt preparation.

IN. K. Hart, S. R. Johns, and

J. A. Lambert.n, Austral. J. Chem., ~ ,

817 (1972).

2F. Lion and A. M. Wil l is.n, J. Proc. Roy.

Soc. N. C. Wales, 73', 240 (1940).

3N. J. Leonard, S. Swann, Jr., and

J. Figueras, Jr., J. Am. Chem. Soc., ~ ,

4620 (1952).

~A. H. Beckett, R. G. Lingard, and

A. E. E. Theobald, J. Med. Chem., 12, 563

(1969).

sj. j. Tufar iel lo and Sk. A. Ali,

Tetrahedron Letters, 4445 (1979).

6A. S. Howard, G. C. Gerrans, and

C. A. Meerholz, ibid., ~ , 1373 (1980).

~T. Watanabe, Y. Nakashita, S. Katayama,

and M. Yamauchi, Heterocycles, ~ , 1433

(1980).

8H. F. Schmitthenner and S. M. Weinreb,

the diketone (~5) (3 mg, 2 %) : IR (CH2CI 2) J. Org. Chem. 45, 3373 (1980)

cm 1710, 1620; NMR (CDCI 3) 6 0.92 (3H,

t, J = 7.5 Hz); MS (m/e) 209 (M+), 208,

190, 181, 166, 164, 152, 139, 138, 136,

120, iii, 110, 97, 96, 83, 82, 81. These

data were consistent with those of report- 1 ed one .

The oxidat ion of 14 with Jones reagent.

To a solution of 14 (50 mg, 0.24 mmol) in

acetone (5 ml) was added freshly prepar-

ed Jones reagent (0.27 mmol) at 0C.

After st i rr ing at ambient temperature

for 3 hr, the mixture was basi f ied with

sodium hydrogen carbonate to pH'9 and ex-

tracted with methylene chloride (3 x 10

ml). The combined extracts were washed

with saturated aq sodium chloride, dried

and evaporated to give the residue which

was subjected to column chromatography

on si l ica gel (5 g). Elut ion with CH2CI 2-

MeOH (9 : i) afforded the diketone (~)

(19 mg, 38.4 %), which was identical with

the authentic sample obtained above.

9B. P. Wi j inberg and W. N. Speckamp,

Tetrahedron Letters, 22, 5079 (1981).

iE. B. Bates, E. R. H. Jones, and

M. C. Whiting, J. Chem. Soc., 1854 (1954).

11E. N. Marvel l and J. Tashiro, J. Org.

Chem., ~ , 3991 (1965).

12R. Green, F. Tonnard, and R. Carrie,

Tetrahedron Letters, 453 (1973) .

13K. E. Pf itzner and J. G. Moffatt, J. Am.

Chem. Soc., ~ , 5661, 5670 (1965).