7/21/2019 Amph.aminomerc.1979

1/4

3580

J .

Org.

Chem., Vol. 44

No.

20,

1979

Table I. Pyrolysis

of

Acetophenone over UOP

N o .

1

Notes

pressure,b

reactant' temp, C mmHg

%

2af

l a 400 0.4 2

l a 500 0.6

11

l a 630 0.7 28

l a 500 33 4

l a 582 760e 2

1

c 614 760e 3

1

c 600 0.5 21

1

ad 600 0.5

0

a

5

g of

acetophenone and 5

g

of

UOP No. 1

were used.

All of the acetophe none had passed through th e tube in

30-60 min. This correspond s at 600

C 1

mmHg) to a

residence time

of

0.3-0.6

s.

used, Run witho ut UOP

N o .

1 present.

e

0.5 SCFM

flow

of

N , was used. Acetophenone ( la ) and small a-

mou nts of water were also recovered. A mass greater than

90% was typically observed.

20 g

of

UOP No. 1 was

Table

11.

Pyrolysis

of

7 at Various Temperaturesa

rea- temp, pressure,

gent C mmHg % 2 a % l a % 7 8

7 420 0.03 95

7 534 0.03 92 tr

7b 529 0.05 95 tr

7 650 0.05

5 6 9 72

7 700 0.05 6 12 36 36

7 760 0.7 30 30

8 760 0.4 37 60

2a 700 0.2 95

-

Without catalyst, product collected in dry ice bath.

Conta ined large acidic glass surface area.

was placed in the reactor and allowed to flash distill through the

tube. Reactions at atmospheric pressure were carried out under

a nitrogen flow of 0.5 SCFM. Volatile products were collected

in dry ice/acetone. Then the products were dissolved in ether

and dried over anhydrous magnesium sulfate and the ether was

removed in vacuo under conditions where losses of phenylacetylene

or

acetophenone were minimized. The products were analyzed

by NMR and GC on a 2-ft UCW 982 column and by comparison

with authentic samples. Results are shown in Table

I.

Synthesis of Diethyl 1-Phenylvinyl Phosphat e

5 ) . To

15.5

g (0.1 mol) of phenacyl chloride in a 200-mL one-neck flask was

added 16.6

g

(0.1 mol) of triethyl phosphite. This was heated a t

86

C

for 4 h with stirring. The product was then distilled at

1 2 1

C

(0.03 mm) [lit.Iobp 101-105

C

(0.005 mm) ], and 21.9

g

was

recovered 86% yield; NMR (CDC13) 7.2-7.8 (m, 5

H,

aromatic

H),

5.25 (d,

2

H, C=CH2,

J =

3 Hz), 4.20

9, 2

H, OCHZ,

J =

8

Hz),4.33 (4, 2 H, OCHZ,

J

= 8 Hz), 1.38(t,6 H, CH3,

J

= 8 Hz).

Preparat ion

of

1-Phenylvinyl Acetate

(7).

To

40 mL of

isopropenyl acetate in a flask equipped with a magnetic stirrer

and distillation head was added

24

g (0.2 mol)

of

acetophenone

and 0.2

g

of p-toluenesulfonicacid. After heating for 7 h at 98-118

C,

15 mL of acetone had distilled and approximately 75%

conversion to

7

was observed by NMR sampling of the product

mixture. The reaction was then cooled, extracted with ether, and

washed once with 10 g

of

sodium bicarbonate in 100 mL of ice

water. The ether was then dried over anhydrous magnesium

sulfate and removed in vacuo. The product distilled at 90

C

(4

mm)[lit. 92-95 C (4.5 mm)]14and18g was recovered 56% yield;

NMR (CDC13) 7.4 (m, 5

H ,

ring H's), 5.60 (d,

1

H, C=CH,

J

Pyrolysis on 7 to

Form l-Phenyl-1,3-butanedione.

nol

acetate

(7 ;

2.0 g) was flash distilled through a quartz pyrolysis

tube a t 650 C at 0.5 mm of vacuum. T he product 8

(1.81

g, 90%

yield) was collected in an ice bath and recrystallized from eth-

anol-water: mp 56-57

C

(lit. mp 60

C);

NMR (CDC13) 7.2-8.0

in,

5 H, ring H), 6.20 (s,

1

H, vinyl H) , 2.60

9,

2 H,

CH2

keto

form), 2.20

(s,

3

H,

CH3). The product

8

was present in keto and

=

2

Hz) , 5.10 (d ,

1

H, C=CH,

J

=

2

Hz), 2.30

(s,

3 H, CH3).

(14) D.

S.

Noyce and R. M . Pollack,

J .

Am Chem. SOC. 1, 19 (1969).

0022-3263/79/1944-3580 01.00/0

enol forms and gave a positive ferric chloride test. Results for

pyrolysis of

7

at other temperatures are reported in Table

11.

All

products were identified by comparison with authentic samples

(NMR, GC).

Registry

No

a, 98-86-2; Za, 536-74-3;

5

1021-45-0;6a, 93-55-0;

6b, 73-32-5;

7 ,

2206-94-2;

8,

93-91-4; phenacyl chloride, 532-27-4;

triethyl phosphite, 122-52-1; sopropenyl acetate, 591-87-7.

Convenient One-S tep Syn thes is o f N-Subs ti tuted

a-Methylphenethylam ines v ia

Aminomercuration-Demercuration

Ronald

C.

Griffith,* Robert

J.

Gentile, Thomas

A.

Davidson,

and Francis L. Scott

Chemistry Department, Pennwalt Corporation,

Pharmaceutica l Diuision, Rochester, Neu: York 14603

Received April

19, 1979

Phenethylamines are

important

natural precursors to

a variety of alkaloid systems' as well as large ring

benzoheterocycles2 and

are

themselves also widely used

as

drugs.3

In

our

present work, we

considered

t he

recently

developed4

aminomercuration-demercuration

reaction

as

a possible general route to N-subst i tuted a-methyl-

phenethylamines

via

a reaction

of type 1, the Markow-

H a X ,

1

2

3

nikoff

product 2 being t h e desirable addend for our

purposes. No such route to N-substituted amphe tamines

has

been

previously described.

Of

particular

in teres t to

us was

the synthesis

of

th e aminoacetaldehyde diethyl

acetal derivative

2a

(R

=

OCH,;

R'

= H, CH,CH(OEt),),

which

is

a useful

synthon for the preparat ion of

3H-3-

b e n z a z e p i n e ~ . ~

Our

initial studies involved, as a prototype

reaction,

the

addition of m-methoxyallylbenzene

(1.2

equiv) to

a

mixture

of

the appropriate mercuric

salt (1 .5

equiv)

and

amino-

acetaldehyde diethyl acetal

(4

quiv) in

T H F with

sub-

sequent heat ing to

60 C

to expedite

formation

of the

interm ediate organomercurials.

In

all

cases, rapid for-

mation of amine-mercury complexes was observe d prior

t o t h e

addition

of

the

olefin subst rate . Th e ra te

of am-

inomercuration proved

to

be

a

sensitive function of

the

mercuric

salt

employed. T h e order of reactivity

of

the

various mercury

salts

increased

in

the order HgClz