1-(Benzoylamino)-3-methylimidazolium chlorochromate (BAMICC), a new selective and mild reagent for the oxidation of allylic and benzylic alcohols

Tmahedron

Lprters. Vol. 36, No. 46. pp 8513.8516. 1995 Elsevter Science Ltd Pnnted in Great Britain

Pergamon

0040.4039/95

$9.50+0.00

0040-4039(95)01784-4

1-(Benzoylamiao)-3-methylimidazolium

Chlomchmmate

(BAMICC),

a New Selective and

Mild Reagent for the Oxidation of Allylic and Benzylic Alcohols Yolanda

Martinez,

Maria

!kpartament~~

Prior

to 1975

compounds first

C’ollms

of

chlorochromate selecttvtty

towards

assoctated

amme

’ Stnce

nttrogens,

complexes

are

the oxtdatton

de hlcali

systems

ltgands

such

than

‘a’9 However. exchange

the

occur

Fyidine (FCC) BppMe (WCC) qmytamino)~idi

alra

1,ENapMhyMine (NapCC) R/raam mm

de

Spain

of alcohols

to carbonyl

trtoxtde-pyrtdme

complex

chlorochromate

(PCC)3,

4-(dtmethylamtno)pyrtdme,5

been

reported

systems

In and

dependmg

stall rematns to gave

Alvarez-Builla”

Madnd

of the pyrtdmium

reagent

the oxtdant

lienares,

for the converston

compounds

oxtdation

and Julio

on the chromtum

have

actd-based

cases

with

used

and Suggs

to carbonyl

m most

may

2X871 -.Alcala

as 2,2 -brpyrtdme,”

rn/er

of alcohols

L. Garcia-Navio

based

by Corey

trtalkylammesX molder

Jo@

reagent

and related

w-tth and

smce

I’n~vrrsldad

the rntroductton

pyrazme””

ltgand

J. Vaquem,

oxochromtum-amtne reagent’

chlorochromate

naphthyrtdme,”

Juan

Orpmca.

the prtnctpal

by Sarett

complexes

baste

dr @mm

was the

descrrbed

A. de las Heras,

show

on the

difficult

1,8-

general,

these

vartous donor

degrees

strength

on substrates

substrate-chromrum

ammeof

of the

contaming

complexes.”

(uvt4Fcc)

BPMICC

Scheme Our

Interest

m new

preparatton

and oxtdant

ftrst

and

ttme

chlorochromate

here

as acyl

properttes we

report

(BAMICC)

Of the vartous group

synthettc

motety

of 1-(acylammo)cyclotmmonium

of chlorochromate our

as a new

N-ammtdes gave

appllcattons

unttal

a nonhygroscoptc

results

chromtum(V1)

explored.

I

salts tn

whtch the

complex

a combmatton and atr-stable

mcorporate

use

of

salts”“’

led us to explore

an N-amtmde

as a hgand

the

for the

I-(benzoylammo)-3-methyhmtdazolrum

oxtdant

of I-methyltmtdazole chlorochromate

as heterocycle salt which

was easily

and the benzoyl prepared

from

8514

the

N-ammrde

2 and

apprecrably prrmary

CrO,

m orgamc

solvents.

secondary

alcohols

and

treatment

of 2-phenylethanol

5 0 equrv

of BAMICC

obtamed

wrth

ketone

m the

usmg

(entry

unsaturated

aldehydes

rsomerrzatron

3)

Like

(entrtes

of the

complex.

w-rthm

Under

was oxrdatron

rn good

of the double

3-S)

are oxrdrzed

two

a hrgher hours

conditions

yields

bond

whrch

although

either

allylrc

the oxrdatron

usmg

was

are also

oxrdized

of Z-2-hexenol

I 5 or 5 equrv

of the

only

resulted

reagent

with

with

those

aldehydes

rate

15 h at reflux

correspondmg

in extensrve

(entry

or

a reaction after

to the

Thus

CH,CI,

contrasts

employed

was completed

of

alcohols.

to the corresponding

of the oxrdant

alcohols

result

dtssolve

of oxrdatron

2) m refluxmg

Thus

m CH,Cl,

not

or benzylic

1 and

alcohols

but the reaction

does

by the absence

of allylic

entrres

the

excess

BAMICC

mdtcated

(see Table, unchanged

When

complexes,

to the slow

to recover

the first

srmrlar

other

of thus reagent

compared

48 h leads

was observed

temperature

HCI

selectrvtty

when

alcohols

I 5 equrv

enhancement

The

of

or 2-cyclohexylpropanol for

benzylrc

presence

a,Pgeometric

6)

1 K2C03 i CH2Cl2 2 HCl/Crq

MSH = 2.4.6.tnmethylixnaresulfo~

hydraade

R 01 R’ = Ar, RCH=CH

Scheme

$4 remarkable 7-9)

conversron other

such

Two

drols

were

tested

10) wrth (58%)

case the mrtral

It should

m the oxrdatron proved

aldehydes

chromrum(V1)

also

product

In the latter

was found

were

obtamed

complexes

of substrates

to be more usmg

farled

reactive I 5 equrv

to give

this

bearing than

basic

benzyl

after

8 h. Under

conversron

nitrogens

alcohol

due

(entries

and

complete

srmrlar

conditions

to above

mentioned

”

(entry

reactron

N-amnude

reported

problems

propanedrol

rmrdazolrum

of BAMICC

as 2- or 3-pyrrdylcarbmol

to the correspondmg

prevrously

exchange

mam

utrltty

Substrates

2

be noted

that

2)

rllustratmg

1 S equrv

afforded

obtained

when

formatron

salt 3 produced 2 (Scheme

for

a further

the selectrvrty the ketone the 1 -phenyl-

of the ketone advantage

can be easrly

of this In 75%

of this

yreld,

reagent

and reused

(entry

actrvates IS

that

The

whereas

I ,2-ethanedrol

presumably

recovered

reagent.

oxrdatron

of 1-phenyl-1,3-

the phenylglyoxal

11) was subJected

the remainmg

primary

at the end of the oxrdatron

to obtain

the BAMICC

complex

was the to oxrdatron.

alcohol

group.

process

the

through

the

8515

Table. Oxidation of Abhols ENTRY

1

ALCOHOL

to Carbonyl Compounds with BAMKK;: CARBONYL coMPouNLl

OH 1: 0”

CONDITIONS Equiv Tii (h) cx-&l,

YIELD?6

10

48

0

10

48

0

OH

2

3

CY-

‘I 0”\

OH

a-

5

6

:I 0%

:I

w”

1.5

8

1.5

20

r. t.

83

5

15

83

1.5

25

92

1.5

2

1.5

2

71

1.5

20

82

r. t.

35

33

1.5

2

reflux

46

5

15

reflux

81

~/2(3:1)

1.5

25

80

E/z(3:1)

81

7

’\ I ok c.k

1.5

8

8

\‘I OH CJ-

1.5

8

83

1.5

8

a3

1.5

20

1.5

20

N

N

Me

9

/ \ @CL

/ \

N

OH

ai

10

reflux

79

OH OH

OH

11 e1:

56

8516

The (10

BAMICC

ml),

mixture and

reagentI

a solution

of the N-ammlde

to 0 “C and the yellow-orange

under

vacua

CH,CI,

(5 ml for

each

alcohol

was consumed

the insoluble

of cehte,

washed

and the solvent

with

K&O,

isolated

the use of BAMICC

the oxldatlon

of allyhc

propertles

and

of this

reduced

benzyllc

alcohols.

and related

reagents

authors

are grateful

was slowly

lncludmg

The

ml).

The

The

The with

was

suspended

was refluxed

supernatant

water m

until

the

was decanted

was passed

carbonyl

reaction

washed

reagent

solution

m 6N HCI

added

mixture

recovered

stirring

removal

and cleaner

the

organic

pressure.

After

by simple

a cheaper

(10

2 was

(15 ml)

yield

IS

ether

(1 g, IO mmol)

by filtration,

added.

combmed

N-amnude

m CH,CI,

HCl

procedure

was

dry

The

under The

m a 83%

oxidation

with ml)

was removed

(0 55 g, 4 mmol)

In summary,

the oxidant

diluted (3x5

of CrO,

was collected

(0 5 mmol)

and then

chromatography

and 2 was

formed

In a typIcal

dry ether

solution

m 20 ml of 6N

solid

and the alcohol

with

To a stlrred

(2 g, 10 mmol)

3.1 g, 92%).

0.5 mmol)

or column

by filtration

for

(yield

2’l

(see table)

residue

by dlstlllatlon residue

as follows.

was cooled

dried

column

was prepared

compound

by treatment

a short

was purified of

for 4 h, the orgamc

and

trough the

phase

insoluble

was separed

of the solvent alternative

those

are In progress

to other

bearing

basic

chromlum(VI)

mtrogens.

In our laboratory

complexes

Further

studies

and WIII be reported

of

on due

course

Acknowledgements y Clencia

and

The

for fmanclal

support

from

for

Comlsi6n

a grant

(MAH)

received

lntermmisterlal

from

de Clencia

Mlmsterio

y Tecnologia

de Educaci6n (CICYT,

proJect

PB90-0284)

REFERENCES 1

Collms,

2

Poos,

3

AND J C G

NOTES

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(a) Corey,

W G

W , Frank,

E

E., Suggs,

Beyler,

J W

I’etruhedron

Scettrl.

A , D’Aurla,

4.

Guzlec,

F S . LUZZIO.

F A

Syntheszs,

5

Guzlec,

F S , LUZZIO.

F A

.I 0rg

6

Davis,

7

(a) Davis.

H

B., Sheets,

(a) Rao,

F

(S),

R

Guerrero.

A

F . Kim,

IO

(a)

S

V , Madln.

(‘omprehensrve 1991

12

Heras,

13

BAMICC

1988.

A

A

Mollna.

A.

M

A . Vaquero,

2647

(b)

Sot

1953,

For a review

75,

422.

of PCC

see:

Plancatelll,

G.

1787

47.

Paudler.

W

W

W . Card,

W.. G

Card,

G. L Heferocycles,

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1983,

20, 2029.

1984,

22,

2029.

(b) Doad,

1980,

808.

(b) Santaruello,

270 S , Slngh. 1983. M

B B . Bhatnagar,

S P Synthesis,

749

S P , Rane,

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F I’erruhedron Adjacent

Trost.

to

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F S Org

Vaquero,

3363.

(Them.

691 1982.

J M

Oxldatlon

Guzlec.

1975.

1980.

Paudler.

Synthesis.

Syn/hesls,

F A..

M

A

1968,

J Am

245

(‘henr.

IH J , Schlecht,

Oqanrc

(b) LUZZIO,

Heras,

M.,

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9

Ley.

R

I,eft. H

L

Letf

1982,

R M , Brannfors.

&es.

C G

E , Mllanl.

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M

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R. A

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1990,

127.

29, 6707 by

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in

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J L , Alvarez-Bullla,

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Left

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1634,

1514,

1273

lH),

7 6-7.5

58,

5862

‘H NMR 3H).

(Received

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yellow-orange (300

MHz.

3 91 (s. 3H)

in UK 28 July

Garcia-Navlo.

powder. D.MSO-d,)

mp

J L 113-114

6 12 80 (bs.

i\lvarez-Bullla, “C, IR (KBr)

1H).

9 46 (s. IH).

J. l’etruhedron v,,,3103, 7 9 (m,

2954, 3H).

7 77 (bs.

ppm

1995:

revised

19 September

1995;

accepted

22 September

1995)

cm-‘. (m,