Solvent participation in additions to olefins

TetrahedronLettersN0.36,

pp.

SOLVENT

3921-3924,

PARTICIPATION

Fred !Department

1968.

of

and

Alfred

JJniversity

Printed in Great Britain.

Press.

IN ADDITIONS

Boerwinklelb

Chemistry,

Pergmmn

of

TO

OLEFINSla

Hassner Colorado,

Boulder,

Colo.

(Receivedin USA 9 May 1968; receivedin UK for publication13 June 1968) the

In discovered adduct

that

derived

conditions of

course

the

so

normal

functional

of

the

our

solvent

from that

the

adduct.

as

the

of

can

bromine

compounds.

cyclohexene

study

the

addition

enter

and

into

solvent.

the

3

We

reactions reaction have

incorporation

of

This

a synthetically

provides

Figure

1 gives

solvent

the

been

can

results

of bromine

we

to

an

very

readily

able

to adjust

reaction

the

exclusion

occur

to

useful of

azide,2

some

total

procedure

give

for

experiments

bi-

using

substrate. Figure

1

84%

0”

r

‘QCH3

2.

92%

The

crude

taken

materipl Sines

to

perform

Preliminary solvent

are

in acetic

adducts.

70%

63%

yields

reaction

4

based acid,

(quant.

experiments

incorporation

isolated

in which

yield)

bromine the

on

azide

reaction

case

which

it

in the that it

material is based

contained

is prone

reveal though

pure

92%

to free

dark

and

chlorine

is more

prone

3921

except on

nmr

to flood

8%

care

solution

exhibits

to free

and

addition, the

case

analysis

bromoacetate

radical

azide

the

in the

radical

of

the

of

the

bromoazide had

with

a similar addition

to

be

oxygen.

tendency than

to 4a BrN3.

3922

~0.36

The

formation

tonitrile

1.

proceed

entirely

different

the

without

cyclohexene isomeric

in simple

ized

of

to

as

attack

form

a Ritter

subsequent

type

formation the

of

methanol

on

reported

to exhibit The

the

on

bromonium

ion

formamide

have

Br + H-

some

data

in acetonitrile

IN3 additions

of

acetonitrile

The

of

tetrazole

formation incipient

followed

methoxy

to

of

ace-

are

listed

which

arises

as

reported

of

below.

to give

Z-butene

give

is apparently can

be

ring azide

degree

rationalbromonium ion

and

attack

of

-NC+

Methanol in bromine solvolysis

Indeed,

formates.

E

through

a proton.

a lesser

shown

with

arises

loss to

trans

ion

tetrazole.

derivative

out

and

collapse

the

subsequent

fi

three-membered

by

azide

tendency

been

and

incorporation

the

and

a similar

to date

and

imino

bromo

us

i n the presence

BrN3

tetrazole

the

the

bromoformylation

in dimethyl

one

intermediate, of

of

incorporation.4b

only

acetonitrile

from

with

alkenes.

cyclization5

The

tions.

solvent

tetrazoles,

addition

attention

contrast

gives

stereospecific

in the

most

results

These

Since

tetrazoles

rece ived

has

in Table

of

has

been

addireactions

6

Y

"20,

Br

/‘-..

Table Acetonitrile Olefin

Incorporation

Adducta a

‘Te *-FH-CH28r

styrene

Addition

m.

Er

cyelohexene

in the

1 of

BrN3

to Olefins yield

.

5

124"

75%

5.

112*

47%

Te trans

2-butene

CH3-~H-~H-CH3

r

Te Br erythro

ais

2-butene

(a)

Se: -

u

r

N\N/N

-Cl-l3 \F

-IDa”

tbrf?D

[b)

the the

remaining product BrN3 adduct.

was

shown

by

nmr

and

ir to be

No.36

3923

The

addition

d-azido

ether

in acetone

9 which

reacts

give

the

alcohol.

This

tion

was

performed

using

in essentially Round

C 41.29,

?ir 2iW

bromo

further

with

the

proven

quantitative

H 6.13,

rmr

with

The

carefo1Jy

and

identical analyzed

by

the

acid

integrated

have

BrN

intensities

of

acetone

(see

reactions

been

were

selected

acecone by

solvolysis

re-

a co-solvent.'

II). and

water,

from

to cyclohexene

used

b-road, 2H,l;

for 1 h'ds determine8

isolated

Table

addi-

H 6.15,

H,l, 6,lTJm with

to

obtained

C 41.23,

treated

was

the

2 was

CgH16BrON3:

2 ~6s

the

present

of 2, when

Intermediate

addition

3

through

of water

trarrs cait~igcration

established

azide

amount

multiplet-14

When

when

and

proceeds

isolation

for

broad

Alcohols

Br2

were

bromine

over

solvents

between

acetic

to

dried

small

acetone.'

(Calc.

7he

alcohol

actual

stretch].

derivatives.

differences

methanol

dried

8.5171s,

1 k'ere formed.

known

the

yield

alcohol of

by

carefully

cm -1 ) no O-H

comparison

in the

the

cm - I , 1676

alu3 bromo

actions

was

to give

in acetone,

Reaction

the

conditions

product

non-overlapping

ratios

proton

were

absorptions

nmr. Table Addition

of

Bromine

to

II

Cyclohexene

in Various

Solvents

Adduct Solvent

% Br,

% BrOS

25 ;:

75 65 26

1. Acetone 2. Methanol 3. Acetic Acid

a.

Principal products were relative amounts approx.

The tion

is much

prising reasonable tion

data

since

from more

1 and

efficient

azide

when

reaction.

Fig.

itself

with

BrN3

is more

one

considers

For

example,

the with

II

clearly than

nucleophilic fate acetic

of

indicate

with

the acid,

than

first

of

BrX

intermediate

given

solvent

bromide,'

X portion the

that At

Br2.

Yield 9: 78

Percentages

brominated acetones. by nmr integrations.

Table

Total

this

are

incorporamay

however in the

seem it

sur-

iS

incorpora-

protonated

No.36

3924

species

u

reacts

acid

is formed

acid

is

This

view

of

from

with

by

This the

bromo

source

the

and

of bromide poor

Linde

by

the

ion

and

hydrobromic

X=N3,

hydrazoic

(K,=1.9

x 10v5).

Havinga,"

appears

tendency

X=Br,

when

azide

dibromide

in MeOH, and

while

of

der

When

HX.

ion,

source

of van

incorporation

only

of

that

after

in the

some

N-bromoamides

HBr

to

11

research

National

acetate3

findings

phenanthrene

incorporation.

from

give

is a relatively

methanol

Acknowledgment:

to

is a good

which

Br2

solvent

CA-04474

X-

is supported

is formed give

which

formed,

reaction

with

was

Cancer

supported

by

Public

Health

Service

Grant

Institute. References

(1)

ja)O;tereochemistry g. Chem. 2,

(2)

A.

(3)

see (a) P.D. Bartlett For examples of solvent incorporation in Br2 additions (b) W.H. Puterbaugh and and D.S. Tarbell, J. Am. Chem. Sot. 58, 466 (1936); 3-g (1957); (c) E.L. Jackson, J. Am. M.S. Newman, J. Am. Chem. Sot. 2, Chem. Sot. 3, 2166 (1926); (d)-P.W. Robertson, N.T. Clarke, K.J. McNaught D.R. Dalton and D.G. Jones, Tetraand G.W. Parrl-, J. Chem. Sot. 335 (1937); hedron Letters, 2875 (1967).

(4)

(a) F. Boerwinkle, Ph.D. Thesis, University of Colorado, 1968; A. Hassner and L. Levy, J. Am. Chem. Sot. g, 2077 (1967).

(5)

J.H. Boyer therein.

Hassner

(6)F.C.

Chang

and

and and

XXXVII. For Paper XXXVI see A. (b) NASA Predoctoral 0000 (1968).

F. Boerwinkle,

E.J. R.T.

Miller,

J. Am.

J. Am.

Blickenstaff,

Chem.

Chem.

J.

Am.

Sot.

Sot. Chem.

Hassner and Fellow.

90_, 216 -

81, -

4671

Sot.

e,

F.W.

Fowler,

(1968).

(1959) 2906

(b) and

F.W.

references

(1958).

(7)

fractionally distilled and used immediately. Dried over Drierite 3 days Solvents, Techniques of Organic ChemFstry Vol. 7 (2nd Ed.) Organic Interscience Publishers (1955) p. 383.

(8)

H. Weiner

(9)

C.G.

Swain

van

der

and and

R.A. C.B.

Lindeand

Sneen, Scott, E.

J. Am. J.

Havinga,

Chem.

Am.

Chem.

Rec.

Sot.

s -

Sot.

Trav.

2181 12,141 -

Chim.

(1963). (1953).

84_,1047 -

Fowler,

(10)

J.

(1965).

(11)

R. Dalton, For example R.O.C. Norman, J. Chem. Sot. (B) 598 (1967), D J.B. Hendrickson, and Il. Jones, Chem. Comm. 591 (1966), S. Bien, M. Ber, E. Flohr, Israel J. Chem. 5551 (7967). -