Nucleophilic substitution at phosphoryl phosphorus

Tetmbedrom Lettem lVo.18, pp 1693 - 1696, 1974.

Pergmon Proan. Printed In Great Britain.

NLCLEOPHILIC SUBSTlTUTlON AT PliOSPHORyL PHOSPHORUS C.R. Department (Reoeived

would

of

solvents

We therefore

from the

phosphetan

gave the to

sulphoxide

lone-pair

substitution that

corresponding

investigate on the

and It

sutphur’

indicated

the

the

of

corresponding namely

of

with

such

e-tosyl

(11

inversion

of

reaction

in which

there

reactlon

of

features isocyanate

thletane-l-oxides

(2-j with

the

recently

in a 5

configuration.

was no compli-

Isocyanates

with

R * I? sB

‘%Ts

I R=

2 Ph, Me

The formation is a well

of

carbodiimides

characterised The best

phosphinimine.4

more recently

No carbodiimide

catalyst

described

is obtained

tJ jp\

which

the

reactlon

the

be the

of

reaction

(J)

isocyanate

proceed

action via

the

of

corresponding

compound now known to

with

N-fluorosulphonyl proceed

beyond

phosphine

be (2). isocyanate.

the

intermediate

I ‘n NP.

0

Ph

phosphetan

to a ccoled

catalytic

(4,.

OCRSO2F

that

to

does not

3 We have found

by the

Is thought

was shown to

because imine

isocyanates

+

I

Ph

frcm

reaction

N-fluorosulphonylphospholene

the

sulphoxides

that

at

oxides.

I?

of

substitution

has been much interest

is possible

reactlon

sulphimide

hetero-atcm,

TsNCO

Hoffmann’

LEI 7Mi.

in nucleophilic

There

in a ring.1

R

oxides

Lelcester.

have been observed

nucleophillc

results

decided

features

at

In the

Preliminary

variety

Smith*

The University,

is constrained

substitution

be observable

(TsNCC).

cation

stereochemical

when phosphorus

in nucleophilic

Chemistry,

and D.J.H.

in UK 19 Februay 1974; aooepted for publioetiem27 Ikroh 1974)

Informative phosphorus

of

Hall

solution

oxides of

(2) the

react

NS02F

4 with

phosphetan

1693

TsNCO remarkably oxide

in benzene

smoothly. gave

the

Addition phosphfn-

1694

go.

imine 2.84

stereospecifically, (9H,

19 Hz), t

(6H,

gave the

(3H,

hydrolysis

occurs

specificity

certainly

only

proceed

with

(2)

as the involves

proceeds

dd,

as unstable

are

retention

of

of

m),

7.76

(3H,

oils

in hlgh

gave the

In view of

by trichlorosilane

phosphine the

oxide

also could

starting

of

the

fact

that

some phosphetan

e-tosyl

azide

and TsNCC.

of

phosphlne

is somewhat surprising

lone-pair, all

of configuration,

d, JPH 19 HZ),

isocyanate

and triethylamine

with

phosphorus

(6H,

d, JPH petroleum)

light

The reaction

yield.

It

(1)

8.45

(6H.

also

as solvents.

methanol

hydrolysis

180°C fC~Cl3, s),

1.75 -

(CDCIJ)

8.81

Chlorosulphonyl

and pyridine

phosphetans

of

that of

Since

reactions

salts. with

stereo-

retention gave the

the

reaction

that

almost

in the

this

7

in benzene

a reaction

the

loss

oxide

cycle

of

the

must

configuration.

F

\

/

-

IPh

P

Cl $IH/EtsN

179 -

clear

T

d, JPH 19 Hz),

m.p.

crossover,

corresponding

petroleum)6,

94%), (IH,

alkaline

the

(6H.

quantitatively.

reduced

retention

8.64

in aqueous

in the

oxidation

with

s),

light

I and 7.5 Hz).

J

essentially

Reaction

same phosphinimine

- 7.65

no stereochemical

oxides

configuration.

phosphetan

7.10 (3H,

(3H.

and f&,

of -6a or g

has been observed

8

7.68

144% (CHCl3,

dlchloromethane

again

with

Phosphetan of

9.04 iminas

respectively,

hydrolysis

m),

In acetonitrlle,

Alkaline 2

m),

(9H,

corresponding out

(IH,

I and 6 Hz),

J

d, JPH 19 Hz),

be carried

a or

dd,

- 3.10

2.24

97,%), m.p.

- 8.06

7.45

9.02

KCC13)

8.75

m),

f&,

18

0 9 3-Me, I-Ph

5

-b3+e,

trans I-Ph -cis

I

NaCtl

6 a 3-Me, - b 3-f&, It formation

is probable of

that

a zwltterlon

I-NTs I-NTs

the

reaction

0

which

of rapidly

trans cis phosphetan closes

oxides

with

TsNCO proceeds

to an intermediate

(2)

with

by rapid relief

of

ring

Ho. 18

1695

strsln, that

giving the

M-l

products

reaction

at -48%

with

(2H,

orders

of configuration.

shows good second order

the situation

kinetics

with

the acyclic

TsNCC In benzene or acetonitriie

R3 = Cl-lzPh (95%) m.p. 6.36

retention

I30 -

131%

a rate

constant

phosphine

oxides

(10) -

more slowly

to give

(UK13

dd, JHH 3 Hz, JpH I6 HZ),

of magnitude

-

7.63

light

(3H,

s),

than the cyclic

8.10

of racemisation

phosphinimine

the half-life

formation

The first-formed 1s now no relief

another

molecule

of

similar

intermediate

of

ring

lsocyanate

phosphinimine

the

ring

the

set-l

(oxygen exchange)

such as 15

could

Since

proceeds

of the zwitterlonic reaction

is not observable

material

with

retention

phosphetan

isothlocyanate

with

indicating

least

three

at

was obtained

as above,

reaction

pathways with (e),

or a

equatorial-

than

racemisation.

similar

to -13 or I& at phosphorus or by

oxide,

Pseudorotat

ion

would lead to racemisation.

formation

obviously

than the nitrogen.

the reaction

but

in phosphorus chemistry.

as a nucieophile

However,

when

whereas the half-life

an intermediate

of phosphine

than product

m),

Further-

of the zwitterion

intermediates

diequatoriai

would give

the oxygen

This

exchange

back starting

of the corresponding

amount of TsNCC gave-the

such a process

(14H,

to (13) -

is slower

because it

that

- 3.10

from equatorial-attack,

the phosphetan oxides,

an equimoiar

2.09

and other

would give

has acted molecule

close

Reaction

be via -I3 or E

Is more nucieophiiic

of configuration.

sulphide

(5081,’

for

ring

and unlikely

via

R1 = Me, R* = Ph,

under the same conditions.

Is slower

arising

the ring

much more quickly

intermediates

could

closure

proceed

another

the R groups or places

racemisation

it

of the zwitterion

involving

room temperature

is unprecedented

whether

I5 minutes

They

e.g.

d, J,-+, I4 Hz),

is about

reaction

by ring

(II) -

TsNCO in acetonitrile.

in the Scheme.

which interchanges

trans

x IO”

is more complex.

Racemic product with

reactions

diequatorial,

which

formation

where oxygen and not nitrogen an intermediate

strain,

followed

a process

loss at phosphorus,’

Racemisatlon

in these

These are outllned

with

was treated

is about 50 hours at

nltterion

are ab ie to compete.

Evidently

by the fact

of 3.09

t fCDCi3),

(3H,

oxides.

more we observed

that

phosphinimines

petroleum),

oxide

as there

is substantiated

with

(+I-(RI-benzyimethyiphenylphosphine

for

This

in CDCi3.

However, react

with

lmine 5

does indeed occur.

(50g)and

e-tosyi

1696

No. 18

R2 -

Ph

R1,R3

= Me,

Et

or

PhCH2

/

;“

R2...*

,P-n

R3/j ,3

j

Ts+qO

;\;_

-14

-

I

2R’R2R3P

-I I Kinetic They

indicate

studies

of

that

intermediate

We thank

the

References

I.

See J.R. 1972,

2.

F.G. 93,

3.

C.R.

an

J.J.

5.

H.

6.

All

For

K.E.

9.

The

formed

a Research

show that

which

a complex

probably

reaction

decomposes

Is

occurring.

by a number

of

pathways.

Studentshlp.

R.K.

Oram,

D.J.H.

Smith,

and S.

Trippett,

J.

Chem.

Sot.,

Perkln

I,

713. Yamagishi, 1916, Hall

D.R.

and D.J.H. Is

Monagle, Hoffmann,

T.W. H.

a general

1900cm-f

than

gave

imines

spectrum (NCS)

unpublished

of and

and

D.J.

Cram,

J.

of

Amer.

none at

see

S.

2240cm-i

D.J.H.

Trippett,

and K.

reaction

Amer.

data

elemental

point ed.

K. Naumann, crude

J.

Mislow, product

(NCO).

rate

of

a discusslon

Monatsh,

spectroscopic

this

Report),

the

McShane,

satisfactory

The

For

Poghossian,

satisfactory gave

observations.

formation.

and H.F.

and G.T.

discussion

G. Zon,

Zwicker,

product

Campbell,

Forster,

Periodical

DeBruin,

E.T.

Chem.

Sot.,

1973,

therein.

Smith

faster

new compounds

i.r.

Rayner,

and references


is

process

= 0 + TsNCO

and Footnotes

chlorosulphonyl 7.

racemisation

for

Corfield,

sulphoxides 4.

the

S.R.C.

-

c

R1R2R3P = NTs

Chem. 1969,

Smith

this 1962,

see

&

the ref.2.

4288.

311. except

the

unstable

Chemistry,

in Organophosphorus

Amer.

of

point

results.

The Chemical

showed

epimerisation

Sot., E,

and all

analysis

J.

of

Chem.

strong

VOI .3,

Society,l972, Sot.,

absorption

1969, at

9l,

p.20.

7027.