51.7

Reference Data

References

1. D. Mathias, Mol. Phys. 12, 381 7. (1 967).

2. R. J . Pugmire, D. M. Grant and M. J. Robins, J. Am. Chem. SOC. 91, 6381 (1969).

3. L. Ernst, Org. Magn. Reson. 8, 161 (1 976). 9.

4. J. A. Su, E. Siew, E. V. Brown and S. L. Smith, Org. Magn. Reson. 10, 122 (1977).

5. J. A. Su, E. Siew, E. V. Brown and S. L. Smith, Org. Magn. Reson. 11, 565 (1 978). 11.

6. G. M. Sanders, M. van Dijk and A. van Velduizen, Red. Trav. Chirn. Pays-Bas 97, 95 (1 978).

8.

10.

12.

A. van Velduizen, M. van Dijk and G. M. Sanders, Org. Magn. Reson. 13, 105 (1 980). 13. A. M. Kook, S. L. Smith and E. V. Brown, Org. Magn. Reson. 22, 733 (1 984). 14. M. Shamma and J. L. Moniot, Iso- quinoline Alkaloid Research 1972- 7977. Plenum Press, New York (1 978). A. Bax and R. Freeman, J. Magn. 15. Reson. 44,542 (1981). A. Bax and G. Morris, J. Magn. Reson. 42,501 (1 981 ).

troscopy in Organic Chemistry, p. 125. Pergamon Press, New York (1 959). D. L. Boger, C. E. Brotherton and M. D. Kelley, Tetrahedron 37, 3971 (1 981 ). G. Gethe, The Chemistry of Hetero- cyclic Compounds, Vol. 38. Wiley, New York (1981); T. Kametani. The Total Synthesis of Natural Products, Vol. 3. Wiley, New York (1 977). G. S. Poindexter, J . Org. Chem. 47, 3787 (1 982).

L. M. Jackman, Applications of Received 7 September 1990; accepted 27 Nuclear Magnetic Resonance Spec- December 1990

Carboa-13 NMR Study of 5-Triphenyl- phosphoranil ydeneaminop yrazoles

ANTONIO ARQUES, PEDRO MOLINA and MARfA VICTORIA VINADER Departamento de Quimica Organica, Facultad de Ciencias, Universidad de Murcia, 30071 Murcia, Spain Jose ELGUERO Instituto de Quimica Medica, CSIC, Juan de la Cierva 3, 28006 Madrid, Spain

13C chemical shifts and '3C-3'P coupling constants are reported for nineteen pyra- zoles bearing an N-PPh, substituent at position 5. The three heterocyclic carbons are coupled with the phosphorus ('J. 3J and ' J ) . These couplings are very sensitive to the nature of the substituent at position 4 [CHO, CH-CHCOMe, CH(CH,NO,),, CH-NR, CH,NHR and CH,N(COR)Ar].

KEY WORDS ',C N M R Chemical shifts J(CP) N-Phenylpyrazoles Iminophos- phoranes

INTRODUCTION

A systematic examination of the literature concerning "C NMR spectroscopy of pyra- zoles reveals that there are reports on hundreds of different C-substituents, but that only one publication to our knowledge has reported phosphorus-substituted pyrazoles.' The latter compounds, I, differ from those described in this present paper, 11, in that the

phosphorus is linked directly to ring position 4, whereas in compounds I1 it is linked to ring position 5 through a nitrogen atom.

X

I

II

In compounds I the three heterocyclic carbons are coupled with the phosphorus with couplings ( ' J and 2 J ) that depend on the substituents X [O, S, Se or nothing (trivalent phosphorus)] and R (phenyl or alkoxy).

RESULTS AND DISCUSSION

As in all cases here R' = Ph and R3 = Me, compounds I1 differ only in the nature of R4: CHO (I), CH-CHCOMe (2), CH(CH2N02), (3) (Fig. I), CH-NR (4), CH,NHR (5) and CH,N(COR)Ar (6). Table 1 contains the most significant values. Although 'H coupled spectra were recorded in some cases, only the 13C-3'P and 13C-'9F coupling constants are given in Table 1.

The '3C-3'P coupling constants can be summarized as shown in Scheme 1, with averaged values for compounds 4,s and 6.

These coupling constants show great sensi- tivity to the nature of R4. An increase in one of the values is accompanied by a decrease in the others, to the extent that the sum of the three coupling constants remains almost constant (about 10 Hz). The variation of 2J(13C-5,31P) and 3J('3C-4,3'P) is probably related to different conformations about the C-5-N single bond. High values of ' 4 3 > 6 > 5, all C-4-Csp3 carbons) seem to corres- pond to more planar conformations ( 3 J is a maximum for dihedral angles p= 0 or 180") than those with low values of 'J(Z > 4 > 1, all C-4-Csp2 carbons) ( 3 J is a minimum for 4 = 90").2 The inverse effect observed for 2J is probably of electronic origin and related to differences in hybridization of the first carbon ofR4(l > 4 2 > 5 > 6 > 3).

These last couplings are so sensitive that the substituent R in compounds 5 affects their values (Scheme 1). Some small 4J coup- lings are observed for C-ips0 of the N-phenyl substituent when the resolution is very good in some cases (3, 5s and 5c). In the case of compound 3 the side chain at position 4 shows 4J and 5J couplings.

EXPERIMENTAL

The synthesis of all the compounds has been described previously: 1 and 4,3 2 and 34 and 5 and 6.'

The NMR spectra were recorded on a Bruker AC-200 spectrometer operating at 50.32 MHz: number of data points, 65536; flip angle, 30"; pulse width, 30 p; acquisition time, 2.0 s; number of scans, ca 1500; spectral width, 12500 Hz; decoupled "C NMR spectra were obtained with WALTZ decoup- ling. All solutions were prepared by dis- solving 100 mg of sample in 1 ml of CDCI, .

518

7GF F F \ . 7ZP'FF

0 1 9 ' 8 7 1

7011 '671 6 F d ' ! F I -!

19F'7FI

7 9 F . 9 7 1 \ C Z 7 '97 I

Wdd

I

I

- 1 6 1 G F I 119'GCI

h d d

M

* -

m 0 3 0

E" 8 'c 0 E 2 4. 0

u)

a f u - c

L Q

OI a ii:

Tabl

e 1. I3C c

hem

ial s

hifts

(6, f

rom

TMS f 0

.01

ppm

) and

13C-31P

and 13C-'9F c

oupl

ing

coas

tant

s (Hz)'

Com

poun

d

1

2 3 4s

4b

4c

4d

4e

4f

La

5b

5c

5d

5e

6f

6a

6b

8c

6d

R4

-CH

O

-CH

-CH

CO

Me

-CH

(CH

,NO

,),

-CH

-NC

,H,

-CH

-NC

,H,M

e @

)

-CH

-NC

,H,F

(p

)

-CH

-NC

H,C

H-C

H,

-CH

-NC

H,C

ICH

-CH

~NC

H,C

H,N

-CH

-

-CH

,NH

C,H

,

-CH

,NH

C,H

,Me

@)

-CH

,NH

C,H

,F

@)

-CH

,NH

CH

,CH

-CH

,

-CH

2NH

CH

,C=C

H

-CH

-NC

H,C

H,N

-CH

-

,C,H

,Me

(P)

'CO

C6H

4Me

@)

,C,H

,Me

(P)

'CO

C,H,

CI

@)

'CO

C,H

,Me

(P)

/C,%

Me

(P)

'CO

Me

-CH

,N

-CH

,N

- c H 2

./ C

8H "

(p'

-CH

,N

c-3

150.

29

'J, c 1

14

8.16

,J,

= 1

.1

146.

73

,J,=

1.4

149.

16

,J, =

1.3

14

9.1 9

"J

, =

1.2

14

9.1 0

"J

, =

1.4

148.

73

,J, =

1.5

14

8.78

,J,=

1.5

148.

42

,J, =

1.6

14

7.1 1

,J

, =

2.2

14

8.17

,JP =

2.2

14

8.00

,J,

= 2

.1

147.

98

"J,

= 2

.3

148.

20

,J,

= 2

.4

148.

10

,J,

= 2

.3

147.

28

,J, Q

1

147.

52

"J,

< 1

147.

51

,J,

= 1

.1

147.

18

"J

m < 1

c-4

109.

51

'Jp=

1.3

105.

15

'J,

= 3

.3

100.

50

'J,=

7.

9 10

6.85

'J,

= 2

.2

106.

97

'J,

= 2

.5

106.

76

'J,

= 2

.3

106.

27

'J,

= 2

.9

105.

89

'J,=

2.9

106.

1 4

'J,

= 3

.1

103.

74

'J,

= 4

.5

104.

11

'J,

= 4

.4

103.

65

'J,

= 4

.3

105.

74

'J,

= 4

.9

105.

22

'J,

= 5

.0

105.

94

'J,

= 4

.8

103.

33

3J, =

5.6

103.

30

3Jp

= 5

.7

102.

96

'J,

= 5

.8

103.

1 3

'J-

= 6

.3

c-5

153.

04

'J,

= 9

.4

150.

45

,J, =

5.4

14

6.39

,J,=

2.

2 15

0.59

,J,

= 6

.8

150.

44

'J,

= 7

.1

150.

65

'J,

= 7

.2

149.

79

'J,

= 5

.8

149.

79

,J,

= 6

.1

149.

21

'JP

= 5

.6

146.

70

,J,

= 4

.1

146.

63

'J,

= 3

.8

146.

62

'J,=

3.

9

145.

99

'J,=

2.6

146.

35

'J,

= 2

.5

145.

99

'J,

= 2

.8

148.

55

'J, =

2.4

148.

55

,J,

= 2

.4

148.

39

,J,

= 2

.5

148.

37

,J.

= 2

.5

3-M

e

14.2

9

15.9

7

13.6

8

14.9

2

14.9

4

14.8

8

15.1

8

14.9

7

14.7

6

12.7

8

12.7

8

12.7

8

12.8

2

12.7

8

12.9

6

13.1

4

13.2

1

13.1

3

13.0

5

C-i

139.

49

139.

74

139.

80

4Jp

= 0

.7

139.

88

140.

01

139.

90

140.

1 4

140.

07

139.

91

140.

60

"Jp = 0

.6

140.

61

140.

50

'J,

= 0.6

140.

47

140.

52

140.

66

140.

59

139.

64

139.

24

139.

52

I -P

heny

l

c-0

C-m

C

-P

125.

01

128.

25

126.

32

125.

1 9

128.

26

126.

31

126.

00

128.

1 8

126.

42

125.

04

128.

09

125.

90

125.

1 4

128.

1 3

125.

93

125.

04

128.

11

125.

95

125.

1 5

128.

1 7

125.

90

125.

1 0

128.

1 9

125.

90

124.

94

127.

91

125.

61

125.

31

128.

04

125.

65

125.

38

128.

05

125.

68

125.

31

128.

01

125.

68

125.

34

127.

81

125.

40

125.

43

127.

92

125.

36

125.

29

127.

88

125.

37

125.

70

128.

04

125.

76

125.

80

128.

1 6

125.

91

125.

58

128.

08

125.

81

125.

70

127.

97

125.

78

R4

-CH

O

182.

94

-CH

11

9.83

; CH

138

.23;

CO

198

.38;

M

e 25

.52

-CH

33

.41

(,JP

= 1

.4);

CH

, 75

.43

(5J,

= 1.

3)

-CH

15

4.17

; C

-i 1

53.7

1; C

-o 1

20.6

1;

C-m

128

.32;

C-p

123

.59

-CH

15

3.53

; C-i

151

.15;

C-o

120

.48;

C

-m 1

28.9

9; C

-p 1

33.1

0; M

e @

) 20

.79

-CH

15

4.16

; C-i

149

.95;

C-o

121

.60;

C

-m 1

14.8

4; C

-p 1

59.8

3; "

J,=2

.6;

'J,

= 8

.0; 'J,

= 2

2.1 : 'J,

= 2

41.4

-C

H

156.

39:

CH

, 63

.94;

CH

137

.44;

C

H,

114.

50;

4J, =

1 .O

-CH

15

6.51

; C

H,

47.1

2; C

80.

83;

CH

73.

73

-CH

15

5.64

; CH

, 63

.03

-CH

, 38

.65;

C-i

148

.32;

C-o

112

.40;

C

-m 1

28.8

0; C

-p 1

1 6.4

9

C-m

129

.30;

C-p

125

.55;

Me

(p)

20.3

9

C-m

115

.10;

C-p

155

.38;

,J,=

1.6;

3

JF

= 7

.2;

'J, =

22.

1 ; 'J

, = 2

33.5

-C

H,

42.6

8; C

H,

51.6

4; C

H 1

37.1

7;

CH

, 11

4.88

-C

H,

42.0

1 ;

CH

, 37

.27;

C 8

2.62

; C

H 7

0.78

-C

H,

43.2

4; C

H,

49.0

3

-CH

, 42

.52;

C-0

17

0.35

; ArM

e 20

.95.

-CH

, 38

.37;

C-i

146

.22;

C-o

112

.60;

-CH

, 38

.06;

C-i

144

.76;

C-o

112

.94;

21.7

1

-CH

, 42

.68;

C-0

16

9.27

; ArM

e 21

.06

-CH

, 42

.52;

C-0

17

0.33

; ArM

e 21

.15

-CH

, 41

.14;

C-0

16

9.88

; C

OM

e 22

.72;

A

rMe

21.0

4

~ ~

~ ~

~~~

-~

~

-

~-

.The

car

bons

of t

he P

Ph,

subs

titue

nt a

bsor

b at

CJ

C-/

130

('J,

=

103

). C

-o 1

32 (,

JP =

10)

. C-m

128

5 (

'J,

= 1

2) a

nd C

-p 1

31 5

(,J

, =

3 0

Hz)

520

Reference data

0 1.3

q r P Phg

9.4 I

1.4 2.6

k$:::;:3 6.4

4

References

3. 1. A. B. Akacha, N. Ayed, 6. Baccar and C.

Charrier, Phosphorus Sulfur 40, 63 (1988). 4.

2. L. 0. Quin, in Phosphorus-37 NMR Spectroscopy in Stereochemical Analysis, edited by J. G. Verkade and L.

1.1 3.3

5.4 2

2-2 4.6

3.3 A ' R = a\kyl ,2.65\

R=aryl ,3.95

1.4 7.9

2:2 3

1.0 5.9

wCH2N \COR

4 4 /Ar

215 6

Scheme 1

D. Quin, p. 391. VCH, Deerfield Beach, FL (1987). P. Molina, A. Arques, M. C. Vinader, J. Becher and K. Brondun, J. Org. Chem. 53,4654 (1 988), P. Molina, A. Arques, P. M. Fresneda. M. V. Vinader, M. C. Foces-Foces and F. H. Cano, Chem. Ber. 122, 307 Received 12 October 1990; accepted (1989). (revised) 18 December 1990

5. P. Molina, A. Arques and M. V. Vinader, Synthesis 469 (1 990).

''0 NMR Study of Isomeric Monochloro- and Monobydroxy- benzaldebydes and Chlorinated Sali- cylaldebydes

E. KOLEHMAINEN (to whom correspon- dence should be addressed) and J. KNUU- TINEN Department of Chemistry, University of Jyvaskyla, P.O. Box 35, SF-40351 Jyvaskyla, Finland

The 1 7 0 N M R chemical shifts of isomeric monochloro- and monohydroxy- benzaldehydes and chlorinated sali- cylaldehydes were measured at 40°C for 0.25 M CDCI, solutions. The "0 N M R chemical shift of the carbonyl oxygen of the compounds studied varies from 506 to 573 ppm measured from external D,O. The observed variation is probably mainly due to the intramolecular hydrogen bonding between the adjacent carbonyl and hydroxyl groups. The 170 N M R chemical shift range of the hydroxyl oxygen is from 80 to 98 ppm.

KEYWORDS 170 N M R chemical shifts Monohydroxybenzaldeh ydes M onochlorobenzaldehydes Chlorinated salicylaldehydes

INTRODUCTION

I7O NMR spectroscopy has gained attention in structural studies of organic molecule^,'^ and the 1 7 0 NMR chemical shift of the aro- matic carbonyl oxygen relates strongly with the torsion angle between the carbonyl double bond and the aromatic plane.4 In 2- hydroxybenzaldehyde intramolecular hydro- gen bonding results in clear I7O NMR chemical shifts to low frequency.' It has been suggested that the conformational prefer- ences of chlorinated aromatics account in the main for their biological activity.6 In this work, "0 NMR spectroscopy was applied in continuation of previous studies on chlorin- ated aromatic^.^

EXPERIMENTAL

Benzaldehyde and monohydroxy- and monochlorobenzaldehydes were obtained from Merck and were used without purifi- cation because their 'H and "C NMR spectra did not show any impurities. Chlorin- ated salicylaldehydes were synthesized from chlorinated phenols by the Reimer-Tiemann methods and purified by crystallization from carbon tetrachloride or ethanol. The purities and structures of the compounds were veri- fied by gas chromatography and by 'H and I3C NMR spectroscopy.

The I7O NMR spectra were measured

with a Jeol GSX 270 FT NMR spectrometer equipped with a tunable multinuclear probe head at 36.5 MHz for 0.25 M solutions in CDCI, at 40°C. Because the solubility of 4- hydroxybenzaldehyde in CDCI, solution at 40 "C was less than 0.25 M, it was recorded as a saturated CDCI, solution and also in 0.25 M acetone-d, solution.

The spectral width was 36 kHz and the number of data points was 8K, giving an acquisition time of 57 ms and a 4.5 Hz per point digital resolution. A 300-ms delay time was used between the pulses to achieve full relaxation before the next pulse.

A proton noise decoupling pulse sequence was used with a 90" flip angle for all mea- surements. A 100-Hz line broadening factor was used prior to Fourier transformation to improve the signal-to-noise ratio in the fre- quency spectra. All chemical shifts are refer- enced to an external D,O sample (whose chemical shift shows a ca. -3 ppm isotopic shift from the value for water'.') in a 1-mm diameter capillary tube inserted coaxially inside the 10-mm diameter NMR sample tube. The accuracy of the chemical shifts is estimated to be +0.5 ppm.

RESULTS AND DISCUSSION

The "0 NMR chemical shifts of the com- pounds studied are given in Table 1. Mono-