Failure of aminophosphonate synthesis due to facile hydroxyphosphonate - phosphate rearrangement

Tm

Lapn, Vol. 34, No. 1. pp. 145-148.1993

PIirMdiUGlWtBdUill

FAILUFE OF A!4IlKlF’IBSPIBN ATE SYNTHESIS DUE To FACILE l.lYImOWHONATE - PHOSPHATE REMuuNcplENT

GANCARZ. , IRENA GANCAFG?

BOMAN *

Institute

of Organic

and Physical

**

Institute

of

Technology

Technical

Organic

University

of Wroclaw.

Chemistry and Plastics

Wybrzeze Uyspianskiego

27,

SO-370 w8ocLAw. POLAND

In a Kabachnlk-Fields synthesis of aminophosphonates Abstract lyse the formation of hydroxyphosphonates. and their further phosphates, unabling the formation of amlnophosphonates. Aminophosphonates still

in 1968 but

and aminophosphonic

today

have received

pounds

the review

see

Ill.

One of

the

very

the one described a reaction pound.

and N.Nwith

first

a subJect interest

methods of

ammonia, dialkyl

bit

later

disubstituted

Fields

the corresponding

and are

substituted

derivatives.

Yields

12% (benzophenone)

biological

phosphite

important

of amlnophosphonates derived

the substitution arguments reaction Based via

that

aminophosphonates

but

rather

due

on the

Fields

idea

or

to

[41,

imines.

[61.

are present at

of

he postulated

The possible

Since

Ka-

followed

by

[71 however presented substitution

the

hydroxyphosphonate

that

amlnophosphonates

reactions

N-

room temperature

hydroxyphosphonates Pietrov

of

(acetone)

in the mix-

are not formed in a hydroxy group

reversibility

con-

N-monoammonia

synthesis

from 40-47X

substrates)

phosphite

via

in

are

presented

formation. are

formed

in the Scheme

(Scheme 11

To that

scheme we added the path

by the mentioned authors. is

undergoes

of hydroxy group by amino group.

hydroxyamlnes

below.

compound and dlalkyl

of

replacing

for

vary

ammonia, carbonyl

the reaction

to be

the common name Kaba-

especially

ture

that

For

carbonyl

synthesis

manner,

& Medved [21 have found that hydroxyphosphonates

of

appears

and corresponding a method of

in a similar

[51 to 0% (fluorenone

These com-

activity.

synthesis

bachnlk

they postulated

compounds

These compounds were obtained

141 presented

still

uknoun

of more than 5000 papers. due to their

These methods have received

amine.

reaction

almost

aminophosphonates

amlnophosphonates

chnik-Fields

[Sl,

great

were

by Kabachnik & Medved 12-31.

between

A little

they are

their

acids

amines can catarearrangement to

a reason

of

many

It

failures

leading

to phosphate.

is known in the literature of

amlnophosphonate

145

It

was not postulated

[81 and as we believe synthesis

especially

it when

146

diary1

\

ketones

are used as a carbonyl

substrates.

\

/

/

c\

b

/ =\

/

OP(O)(OEt)2

Ii

HONHR

1

1 \

\/ /\

\

c=NR

RN;;P(O) (OR)2

b

/ Scheme 1. R=alkll. We observed periments

the reaction

course

tures

the

three

ments were phate

proved

about

compound. with

It

phosphite

was found

amine (no matter product

explaln

it

or

as

was

for

95% for

The

run

the

the mixture all

hydroxyphosphonate

60% and

for

the retempera-

We also

and heating

and comparison of

any allphatlc

ln

was also If

it

products

at

experl-

and phos-

acetone,

aceto-

identity

the spectra

several

amine with

is allphatlc

Aromatic

experiment hours,

that

only

with

was

that

In

or

of

heating

amine8 as weak basic

fluorenone

hydroxyphosphonates

the fluorenone

in the absence

N-substituted

N-ethylaniline

was used as a carbonyl

while

traces

heating

or aromatic) lmlne,

aniline

when fluorenone

shown that while

corespondlng

follow.

also

a separate

at SO-90°C for It

of

that

only at higher

amlnophosphonates

respectively.

syntheses

experiments

indicating

was observed.

of

0%. 8X,

70% of amlnophosphonates

were obtained.

only

ylelds

NMR ex-

[91.

butylamlne

to over

reaction

and fluorenone,

independent

mixture

Replacing

differences

amounts of reagents

about

In all

and dlethylphosphlte

72 hrs and in separate

87%. 46%. 20%. 0% and yields were

methods.

butylamlne

two NM experiments,

the

The calculated

together

by their

of

the equlmolar

benzophenone

the studied

ketone,

for

In these

progress

hrs.

measured

phenone.

led

Is different

by nlxlng

60°C for

of

There were no substantial

greater

reaction,

by NMR and kinetic

mixture

in room temperature

3 hrs at 55-60°C. action

progress

1: 1: 1 (mole ratio)

in C6D6 was left

aryl

with

fluorenyllmlne. species

primary

of phosphite

do not

the

We can “activate”

147

the dlalkyl

phosphites,

The condltlons

and the reaction proceeds vla hydroxyamine-lmlne path.

are dramatically

changed when any alkylamlne appears.

much stronger bases and they “activate”

the dlalkyl

They are

phosphite in a manner pro-

posed by Springs & Haake [lOI (path A or B). UtO)2P(O)-

such activated tes.

+ N+H3R A

dialkyl

Reversiblllty

of

RP(O)(OHcR)2

phosphltee

react

reaction

should

this

+ NR2R -A

with ketone forming still

allow

rearrangement, only phosphate is formed lrreverslbly reaction also by klnetlc tion

and Its

droxyphoaphonate

was

(A 1400 nml in methanol with respect

Table

to fluorenone.

Considering prlmary

especially

1.672 1.457 1.212 1.064 0.332 0.939 0.841 0.778 0.676 0.046 0.295 0.057

but

tertiary

it

reversible.

an excess

as

of

a

hydroxyphosphonate

the above conclusion. dlssappearance

amine and phoephlte

data are presented

of

formaThe hy-

fluorenone

(100 times)

in Table

with

1.

(cl/co)(see

Table

8.33 11.01

1 formation

allow

and tertiary

amines seperately catalyst,

one can see

whereas

the 2)

(co).

of hydroxyphosphonate

the formation

of

was observed

when the excess

of

10.71 10.77 9.33 10.96 10.49 11.12

secondary

reversibility

hydroxyphoephonate formation

10.83

0.036 0.011 0.017 0.025 0.0035 0.0057 0.0013 0.010 0.0010 0.003 0.0012 0.0014

amines are the strongest

In Table

This

x lo2

secondary

and

amlnes are much weaker catalysts.

should

A= 400 nm (cl)

by

f f f f f f f f f f f f

the primary. allphatic

As shown also

of

product. Since

1

t-butylamlne lsopropylamlne n-propylamlne n-butylemine benzylamlne dilsopropylamlne dfethylamlne piperidine dibutylamine morpholine trlethylamine trlbutylamine

cess,

phosphonate - phosphate

as a final

of

can prove

observed

The obtalned

k obs[sek-‘l

that

as the kinetics

to phosphate

formation

of amlno-

(gives only hydroxyphosphonate) we studied this

methods,

rearrangement

:NR2R

hydroxyphosphona-

the formation

phosphonate unless in another competing reaction like fluorenone behaves dlfferently

(ROl2POR

of

corresponding

monitoring

amine (100 times)

The complete

is

aminophosphonates

fluorenone

is a measure of reversiblllty

should

fluorenone vs.

fast

long

as

proit

formatlon

was added to

reversibility

amount of

rather as

the

be

(co).

rearangement.

The

is

at

solution

manifested ratlo

of

148

Table

2

amine

ester

\

dimethyl

trlethylamlne n-butylamine t-butylamine

Data

2 show that

rearangement,

constants

are

all

6.2*10-4

reaction

respectively.

the forward

reaction.

We also

studied

the ketone

ketones

and further

15

used

amines this

aminophosphonate usually

up.

6-8

times

the reaction

For aromatic

only

reversed

phosphonateThe observed

the rearrangement

two orders formed mixture

slower

than

irreversibly

for

does not lead

to

161. path

and especlaly that

by heating

used.

for

about are

is

than the

[sek-‘1

are

rearrangement

path becomes so fast in a good yield

of

products

formation

slower

phosphonates

and 1.0*10-4 Thus they

heating

but to a decomposition

the ketone

is

found that phosphates

Thus the phosphonate-phosphate

phatic

it

amines and all

and reverse

all

0.19 0.17 0.15

the hydroxyphosphonate

for

of order

diisopropyl

0.15 0.14 0.16

12-19X which means that

phosphate rate

0.13 0.13 0.12

in Table

in about

diethyl

it

is

is

like

a

diaromatic imposible

a mixture

of

by which

'sink',

ketones to obtain

three

and alia desired

reagents,

as

is

done. In this case one must follow two step synthesis: preparation of

imine. followed by addition of phosphlte.

Heferences

1. P.Kafarskl 81P.Mastalerz, Beltr.Wfrkst.Forsch., H21.1. (1984) 2. M. J. Kabachnik & T.Medved, Izv.Akad.Nauk. SSSR,Ser.Chim.. 1953.1126 3. M.J.Kabachnik ILT.Medved, Izv.&ad.Nauk.SSSR,Ser.Chia., 1954.1024 4. 5. 6. 7.

E.K.Fields. J.&Chem.Soc.,74,1528 (1952) T.J.Medved & M.T.Kabachnik, Boklady Akad.Nauk SSSR, 84.717.(1952) FLGancarz. to be published

K. A. Petrov. V. A. Tchauzov, T. S. Yerokhina, 2h. Obsch.Khfm., 45 ,737. (1975) 8. see for example A. F. Janzen, T. G. Smyrl, Can. J. Chem., 50.1205 (1972) 9. For example: Equimolar amounts of Synthesis of diethyi-9-hydroxyfluorene-9-yl-phosphate. fluorenone. dlethyl phosphite and n-butylamine was allowed to stay in the room from 1: 1 mixture of temperature for 20 minutes, then product was crystalised 146-147Oc, yield 90x, lH-NMRUzDCL3); hexane; mp toluene and

8.13-7.25(m,SH.ArH),5.25(s,lH,OH).4.13-3.63(m,4H,CH2),1.03(t.6H.CB3). Synthesis of diethyl none,

diethyl

was crystalised

(fluoren-9-ylbphosphate. phosphite and butylamine was let from hexane;

Eequimolar amounts of to stand for 24 hours.

mp. 48-49'C. yield 80X, lH-NMR

fluoreProduct

(CDC13); 7.87-

7.19(m,SH.ArH), 6. 21(d,lH,CX,JHP=9Hz).4.25.4.13(d*q,4H.CH2),4.13(t.6H.CH3). see

also

H.Tlmsller.J.Kurtz,Chem.Ber.,lOl,3740,~1971~;R.Gancarz.J.S.Wieczorek

J.Prakt.Chetie 322,213(1980);R.Gancarz et al.,J.Prakt.Chemfe.329(11,165(1987), J.Prakkt.Chemie,326.349~1984); and references cited therein. R.Gancarz et al., 10. B.Springs & P.Haake. J.Org.Chem. ,42,472 (1977) The part of the work was presented on a poster session of XII Znternational Conference on Phosphorus, Chemistry. July 1992, Touluse, FRANCE

CRcceivcdinUK20 October 1992)