The action of mercaptoacetic acid on a trialkyl epoxide

Tetrahedron printed in

Letters,Vo1.27,No.32,pp Great Britain

3781-3782,1986

0040-4039/86 $3.00 Pergamon Journals

+ .OO Ltd.

THE ACTION OF MERCAPTOACETICACID ON A TRIALKY’ EPOXIDE

Stefan

Tun Abdul

T. Orszulik’

Razak Laboratory,

Research

Association,

The Malaysian

Brickendonbury,

Rubber

Producers’

Hertford,

SG13 BNL,

England

The reaction between 2,3-epoxy-2-methylpentane and mercaptoacetic acid yields a Abstract: 3:4 mixture of the thialactone (2) and the hydroxyacetate (2). Using milder reaction only the mercaptoester (3a) is formed, which has been shown to be an intermediate conditions, The reactivity of mercaptoacetic acid towards the in the formation of the acetate (3b)r epoxide is not due solely to the action of the mercapto or carboxylic acid group and therefore may result from the formation of cyclic intermediates.

Although been

nucleophilic

carried

studies

out

2 have

and the

shown that

lactone

functional

addition

on either

(2),

groups

various

which

of

to

polyalkyl

is

the

oxirane

epoxides

or

mercaptoacids

ring the

add to

in accordance

with

has

been much studied,

addition

of

epoxides

the

expected

to give

R.5-f I

‘bH’R2 (L)

k,

a similar

2,3-epoxy-2-methylpentane;

our

A mixture

rubber.

2,3-epoxy-2-methylpentane

These (2,

together

were

separated

0.33g)3

and,

The initial -3b or both,

the

a product

starting

by preparative

surprisingly, product,

was formed

n=l

this

epoxide

mercaptoacetic

in chloroform

Initially with

in of

R2=Et,

on the addition

interest

(2.Dg)

analysis.

OHR

2

(3) Rl=Me,

study

epoxidized

consumed,

(L),

the

k,

(1)

out

m

Rl

(a)

by h.p.1.c.

of

S).C0.CH2X

R1\

‘S

R1w R,

natural

the hydroxyacid

nucleophilicity

(C,H$”

carried

work has

More recent

the mercaptoacids.

HO2C-(C\H2),

We have

little

mercaptoacids.

(Sml)

h.p.1.c.

lies

and found

the hydroxyacetate

(2,

which,

to be

R2=Et,

X=SH

R2=Et,

X=H

in its (1.89g)

was refluxed

and two major

Rl=Me, Rl=Me,

mercaptoacetic

acid

was observed

materials

of

(a) (b)

being

to

a model

for

and

and the

as reaction products

acid

were

the expected

reaction continued, observed

monitored was (66h).

thialactone

D.44g).4’5

which could be an intermediate in the formation of either 2a or as a major product when the reaction was carried out at room-

3781

3782

temperature

for

It

24 h.

hydroxymercaptoester mercaptoester

(&,

mercaptoacetic converted

acid

towards

of

and/or

used

for

the

the

in

required at

ion, the

4;

reaction

(15OOC; present

significant

to

could

the

to assess

these

a monofunctional

reaction

are

of

and absence

of

was efficiently

thiol

and/or

The reaction &,

using,

be observed

form

and acetic

the extent

the

presence

after

conditions

24 h.

It

via

reactions.

7We

much more vigorous

quantities

of

the acetate

any steric

and inductive

acid

were

the

acetic

seems

assisted

in other

acid,

carboxylic

as required,

may be anchimerically

known to

detectable

the

intermediate

investigated.

moiety

epoxide

produce

the

the mercaptoester

acid

in

the

intermediacy,

analysis).

of

also

of

intermediates

between

3 h)

able

in

were

formation

a carboxylic such

cases,

giving its

was refluxed

In both

actions

h.p.l.c.,

investigate

-3b (h.p.1.c.

In no case of

to

(2ml)

90 h.

findings,

in

addition

sulphonium

not

(0.07g)

n-hexanethiol. the

that,

in chloroform

the hydroxyacetate these

by preparative

In order

2,3-epoxy-2-methylpentane

same as those

that

0.38g).6

0.15g)

to only

In view

was separated

(z,

acid

likely

a cyclic have

found

conditions

(3b). -

However,

effects,

which

are we are

may be

reactions. H-S+ HO

-+

0

(4)

ti Acknowledgements: Research n.m.r.

The author

Association

for

and h.p.1.c.

is

permission

grateful

to

publish

and to A.van

analyses,

Raalte

References

1.

Present

address:

Fasson(Nederland)bv,

to this

the

Board

work, for

of

the Malaysian

to M.J.R.Loadman

experimental

Rubber

Producers’

and A.D.Edwards

for

assistance.

and Notes

Research

and Technology,

P.O.Box

28,

2300 AA Leiden,

The Netherlands. 2.

K.Jankowski,

3.

NMR(CC14)

R.Coulombe, B4.02(1H,t,J

and C.Berse,

Bull.Acad.Pol.Sci.Ser.Chim.,

6,CH-0),3.7-3.55

1.35(3H,s,CH3CS),1.30(3H,s,CH3CS),1.07(3H,t,~ 4.

NMR(CC14)

64.65(1H,dd,J

5.

acetic

of

acid,

6.

7,CX3CH2).

the acetate

which

(ion-exchange

(1971).

IR(neat)

174O(CO)cm-l.

is

was found

not

IR(neat)l730(CO)cm-l.

due to contamination

to be present

Found:

of

S,

<0.5X.

the mercaptoacetic

in a concentration

acid

by

of only 360 pg/g

chromatography). B4.68(1H,dd,J

NMR(CDC13)

7, C!3-CH2).

661

l.6(2H,m,Cl12-Me),

4,10,CH0~,2.04~3H,s,CH3C0~,1.95~1H,br,OH~,l.6~2H,m,C~2Me~,

1.13(6H,s,E2COH),0.88(3H,t,J The formation

-19 (11-121,

and 3.17-3.0(2H,ABq,CH2-S),

9,3,CH-0),3.48(1H,br,OH),3.21(2H,d,J

1.57(2H,m,CIi2Me),l.15(6H,s,Me2COH),0.90(3H,t,J

7,CH2E).

9,CH2S),l.97(lH,t,J IR(neat)

9,SH),

3460(OH),2560(SH),

1725(CO)cm-1. 7.

E.S.Gould, New York, (Received

‘Mechanism 1959,

p.561.

in

UK 13

and Structure

June

1986)

in Organic

Chemistry’,

Holt,

Rinehart

and Winston,