Oxidation of 2-substituted allylsilane to conjugated enal using hypervalent organoiodine compound and synthesis of α-methylen γ-and δ-lactones

Tetrahedron Letters,Vol.24,No.8,pp Printed in Great Britain

OXIDATION

OF 2-SUBSTITUTED

ORGANOIODINE

COMPOUND

0040-4039/83/080777-04$03.00/O 01983 Pergamon Press Ltd.

777-780,1983

ALLYLSILANE

TO CONJUGATED

AND SYNTHESIS

ENAL USING HYPERVALENT

OF a-METHYLENE

Y- AND r;-LACTONES

MasahitoOchiai and Eiichi Fujita* Institute

for Chemical

Research,

Kyoto University,

Masao Arimoto Osaka College

Summary:

2-Substituted

etherate

in dioxane

y- and &lactones

organic

peracids

conjugated

with

Osaka-Fu

580, Japan

iodosobenzene

enals 2 directly

and boron trifluoride

in good yield,

has been little

intermediates

studied. 293 Oxidation

does not seem to be a highly applicable

of allylsilanes

or allylselenides

followed

by oxidative

to give allylalcohols

report a new useful direct oxidation hypervalent

1 on treatment

have been shown to be versatile

however,

desilylation

Matsubara,

from which a-methylene

7 were synthesized.

Allylsilanes oxidation,

afforded

611, Japan

and Hideo Yamaguchi

of Pharmacy,

allylsilanes

Uji, Kyoto-Fu

organoiodine

inorganic

of allylsilanes reaction.3

rearrangement

with

or phenylseleno-

of the resulting

allylsilanes

Their

to ally1 alcohols

Phenylthio-

has been shown to be an effective

of 2-substituted

synthesis.'

allylsulfides

process. 394 We wish to

1 to conjugated

enals 2 with

compound.

C6H51=0

SiMe3

0

BF3-Et20 dioxane 1 Hypervalent

organoiodine

alcohols,

carbonyl

treatment

with

etherate

Representative

compounds,

iodosobenzene

(BF3-Et20)

compounds sulfides, (2 equiv.)

(1 equiv.)6

have been known as mild oxidizing and

ketenes

activated

in dry dioxane

results

are indicated

in Table 1.

In this reaction,

the formation

of iodobenzene

777

has been published.5

by the coordination

afforded

reagents;

conjugated

was usually

oxidation

Allylsilanes

1 on

with boron trifluoride

enals 2 in good yield.

observed

on TLC.8

of

The use of

778

Table

1

Oxidation

of Allylsilanes

to Conjugated

Allylsilaneb

1

Enals with

Conjugated

OAc

To a stirred

71

suspension

of allylsilane

the mixture

was stirred

the mixture

was extracted

Evaporation

conjugated

enal 2.

of the products. the isolated germane obtained

For preparation

instead of dioxane

at room temperature

ice-cooled

aqueous

The extract was washed

TLC (hexane-ethyl

acetate,

in

NaHC03

with brine and

5 Q 7

: 1) pure

of la and lb-le, see ref. 7 and 6, respectively. -._ __ _I

afforded

a complex mixture

of the reaction

bond was kept intact

3 was also oxidized

AcO

was observed: C6H5AGeMe3

(see le + 2e). Allyl.. __

in a same manner,

3

but enal 2d was -...

in only 30% yield.

The activation be very important, reaction

b)

( 2 equiv.) in dry dioxane

dropwise

After adding

with ether.

gave after preparative

Chemoselectivity

double

(1 equiv.)

for 12 hr.

Isolated yield.

ether as the solvent

1 and iodosobenzene

of 1) was added BF3-Et20

solution,

c)

Yield, %'

OAc

nitrogen;

dried.

2

II

OAc

(ca. 250 ml/mm01

Enal

and BF3-Et20a

OAc SiMe3

a)

Iodosobenzene

of iodosobenzene because

by the coordination

the oxidation

sequence

shown in Scheme

The first step of the reaction a transient

intermediate,

of iodosobenzene Conjugated

were required.'

to give 5.

may be the formation

Decomposition

enals 2 were smoothly

BF3-Et20.

In the

In view of these observations,

1 seems to be plausible.

which will be attacked 11

to its oxygen atom seems to

of 1 does not proceed without

more than 2 equiv. of iodosobenzene

the reaction

of BF3-Et20

of the highly reactive

by the nucleophilic

of 5 produces

coverted

enal 2.

species

41° as

oxygen of another molecule

12

to cl-methylene y- and b-lactones

7. 4b

The

779

C6H51=0

@ 0dC6H5

-C6H51

5

H

Scheme Table 2

Synthesis

of a-Methylene

a,B-Unsaturated

Enal

?b

y- and 6-Lactones

from Conjugated

Yield, %

y- and &Lactone

Acid

eCo2H

1

6b

83

6_c

99

Enals

Yield, %

7b

72

7d __

59

OAc --. 2c

w 02H

2!

C6H5&

C02H

6d .--

91

6:

a'

AcO 2_'

MCO?H

aldehyde

2b on treatment

2-butene,"

by the treatment

7b in 72% yield. ..-

Thus we developed 1, yielding

in the presence

gave cc,B-unsaturated acid 6b in 83% yield. _-.

MeOH) followed 6-lactone

with sodium chlorite

conjugated

a new convenient

of the lactone method

(a) H. Sakurai,

Pure Appl.

1979, 761; (c) M. Ochiai lll_ 2.

J. M. Reuter, A. Sinha,

3.

(a) I. Fleming

Chem.,

hydrolysis

in pyridine

synthesis

for the oxidation

enals 2, by using hypervalent References

1.

Alkaline

with dicyclohexylcarbodiimide

The results

of a chlorine

afforded

of 2-substituted

the desired

in Table 2. allylsilanes

compound.

(b) T. H. Chan and I. Fleming, Synthesis,

and E. Fujita, J. Synth. Org. &em.,

and B.-W. Au-Yeung,

of 6b (NaOH/H20/ __

are summarized

organoiodine

2-methyl-

and Notes

I_ 54, 1 (1982);

and R. G. Salomon,

scavenger,

Jpn., 40, 508 (1982). -_

J. Org. &em., 43, 2438 (1978).

Tetrahedron,

I_

3_7, Supplement,

J. Carter and I. Fleming, J. Chem. Sot., Chem. Comm., 1976, 679; VU__

No. 9, 13 (1981);

(c) Epoxidations

(b) M. of

780

allylsilanes

are reported

P. F. Hudrlik

4.

and G. P. Withers,

(a) H. Nishiyama,

K. Itagaki,

(b) Cf. H. Nishiyama, 5.

(a) A. Varvoglis, (1966);

to give poorly characterized Tetrahedron

K. Sakuta,

H. Yokoyama,

Chem. Sot. Rev.,

(c) R. B. Sandin, ibid.,

mixtures

of cleavage

procudts:

Lett., ____ 1976, 29.

and K. Itoh, Tetrahedron

S. Narimatsu,

and K. Itoh, ibid.,

10, 377 (1981); __

32, 249 (1943): __

Lett., i??,5285 (1981); 23, 1267 (1982). __

(b) D. F. Banks, Chem. Ileu., 66, 243 __

(d) T. Takaya,

H. Enyo, and E. Imoto, BUZZ.

Chem. Sot. Jpn., 41, 1032 (1968).

__

6.

M. Ochiai,

E. Fujita, M. Arimoto,

and H. Yamaguchi,

J. Chem. Sot., Chem. Corn., in press.

7.

M. Ochiai,

E. Fujita, M. Arimoto,

and H. Yamaguchi,

&em.

8.

In the

oxidation

of allylsilane

la, iodobenzene _-_

Pham. BUZZ., in press.

was obtained

in 72% yield

(GLC yield)

based

on iodosobenzene. 9.

Allylsilane

la on treatment 5_

with

1 equiv. of iodosobenzene

gave conjugated

enal 2a in only -...

33% yield. 10.

Umemoto alkenes,

11.

amd co-workers arenes,

recently

and thiols with

S. Nakayama,

and 0. Miyano,

The reaction

initiated

reported

the useful

perfluoroalkylations

(perfluoroalkyl)phenyliodonium

(a) J. Wicha, A. Zarecki,

3635; (b) R. M. Moriarty,

salts: T. Umemoto,

23, 1471 (1982) and references Tetrahedron Lett., __

by the attack of oxygen of iodosobenzene

atoms has been reported:

of carbanions,

S. C. Gupta,

to electron

cited therein.

deficient

and M. Kocor, Tetrahedron

H. Hu, D. R. Berenschot,

Y. Kuriu,

carbon

Lett., ..___ 1973,

and K. B. White, J. Am.

Chem. Sot., ___ 103, 686 (1981). 12.

The partial out.

participation

of the following

Water may be produced

alternative

by the condensation

reaction

sequence

of trimethylsilanol

cannot be ruled

during

the reaction.

OH BF3

C6H51=0 OH

-C6H51

F

R

0 BF3-Et20

R

I IC6H5 -+

2

A/

-Me3SiOH

In fact ally1 alcohol (1 equiv.)

8 on treatment

and BF3-Et20

(1 equiv.)

with

iodosobenzene

in dioxane

OH

at room OAc

temperature 13.

afforded

enal 2b in 59% yield. __

B. S. Bal, W. E. Childers,

and H. W. Pinnick,

(Received in Japan 8 November 1982)

8

Tetrahedron, 37, 2091 (1981).