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A novel route to formamides and their derivatives. Reduction of isocyanates via hydrosilylation catalyzed by palladium
TetrahedronLetters NO. 44, pp 4363 - 4366, 1973.
A NOVEL ROUTE TO FORMAMIDES REDUCTION
OF ISOCYANATES
PergamonPress. Printed in Great Britain,
AND THEIR DERIVATIVES.
VIA HYDROSILYLATION
CATALYZED
BY PALLADIUM
Iwao Ojima* and Shinichi Inaba Sagami Chemical
Research Center,
4-4-l Nishi-Onuma,
Sagamihara
229, JAPAN
and Yoichiro Nagai Department
of Chemistry,
Gunma University,
Kiryu, Gunma 376, JAPAN
(Receivedin Japan 31 August 1973; received in UK for publication25 September1973) Among the hydrides of the group IV elements, to react with isocyanates
across the carbon-nitrogen
organo(N-arylformamido)tin can be further converted distinctly
differnet
N-methylamines.' hydrides without
organotin hydrides
double bond to afford a tri-
1. or a triorgano(N-alkylcarbamoyl)tin to N-arylformamide
with triorganotin
from the reaction of isocyanates
The corresponding
are known
The formar
2.
hydride.
1
This is
with LiAlH4, which produces
reactions of silicon hydrides
have not been reported and in fact they lack reactivity
and germanium toward isoqanates
a proper catalyst. -
R3SnH
R3SnN(R')CH0
.->
R'NHCHO
(R' = Aryl)
+ R'NCo
-1,
R3Sn[-NHR' O
We found, however, in the presence
that a hydrosilylation
(R' = Hexyl)
2 of isocyanates
of PdC12 or Pd-C, and that the orientation
on the structure
of isocyanates.
of triethylsilane
does really occur
of the reaction
Now, we wish to report novel catalytic
with isocyanates,
depends reactiami
which furnishes a novel route to formamides
and their derivatives. M-Naphthyl
isocyanate was allowed to react with triethylsilane
sence of 0.1 Mel% of PdC12 or 10 % Pd-C at 80" for 2-3 hr.
4363
in the pre-
Distillation
of the
4x4
No. 44
reaction mixture amide
under reduced pressure
(3) in nearly quantitative
smoothly solvolyzed yield.
yield.
The silylformamide
to N-IX-naphthylformamide
The silylformamide
(2) quantitatively
gave N&-naphthyl-N-triethylsilylfonn-
(4) by methanol
2 was also converted
Et5SiH -
MeOH PdCQ
in quantitative
to N-IX-naphthyl-N-acetylformamide
by the reaction with an equimolar
N=C=O
3, thus obtained, was
acetyl chloride.
,
+
Bt9SiOMe
HNCHO
Et3Si-N-CHO
or Pd-C
2
Et9SiCl
+ CH9CONCHO I Phenyl isocyanate
and n-butyl isocyanate were hydrosilylated
fashion by triethylsilane tion of triethylsilane these isocyanates
in different
in the presence of PdC12 or 10 % Pd-C.
was observed across the carbon-nitrogen
in the opposite orientation,
Thus, the addi-
double bond of
and hitherto unknown
silanes, 6a (R = Ph, 95 %) and 6b (R = n Bu, 46 %), were obtained. of the carbamoyl
cleaving carbon-silicon
+
The reaction
silane a with acetyl chloride afforded N-acetylformamide
excellent yield, which might be formed through N-acetylcarbamoyl
R-N=C=O
carbamoyl
Et9SiH
2 in
silane 8 with
bond.
.--J PdCIZ or Pd-C
RNH-C-SiEt5 II 0
MeOH .->
RNHCHO
1
a [CH3CON(R)COSiEt3]
a:
R = Ph
b:
R = n-Bu
Jj
[HCi] I CH9CO(R)NCHO 2
+ Et9SiCl
No. t$J
4365
The nmr spectrum of the carbamoyl tautomerism observed
between
the structures
in the case of 2,
in the region
t
silane 6a suggests the existence of a 4 6A and 6B. A similar phenomenon was also -
i.e., the nmr spectrum of 7a displays
8.30-9.40.
After D20 treatment,
while two singlets remained, which are reasonably structures,
-7A and -7B.
The situation
Spectral data for these formamides
PhNH-C-SiEt3
.A
Compound
PhND-C-H
I
II
HO
0 6B -
3
__-
to C-H protons
of the
-
13c=o
NH or OH
I -7B
1670sh
___
and Their Derivatives5
(5, -CH=O
PhN=C-H DO
with Isocyanates
NMR
are listed in the Table
-
-7A
IR (cm-') 3NH
assigned
and their derivatives
1:l Adducts of Triethylsilane
mi?k2 -----
two broad singlets disappeared
is similar in the case of 6b and -* 7b
PhN=C-SiEt3
6A -
four signals
Bp('C/mm) -COCH,
7.05
or Mp(°C)
140/0.12
1630 4
3200
1655
8.63
8.63
141-142 (lit.,6 137.5)
5
___
1650
---
6a -
3270
1675
7.64 8.27
7a -
3240
1670
8.61 9.00
8.35 8.79
9a -
--_
1720 1685
_-_
9.40
10.60
1.94
79-81 go/o.45 45-46 (lit.,7 47.5)
2.05
55-57 (lit.,8 56-57)
6b -
3300
1670
8.12 8.17
7b -
3260
1660
7.00-7.44
82/1.0 8.03 7.83
130/20 (lit.,' 123/16)
9b -
--_
1725 1670
-__
9.17
2.41
135/15
No. 44
4966
Consequently,
the hydrosilylation
of isocyanates
may open a novel device for the preparation thesis of a new type of silicon compounds, ately formed silylated a good precursor
formamides
of N-acetyl
catalyzed
of formamides carbamoyl
and carbamoyl
by palladium
and also for the syn-
silanes, and the intermedi-
silanes have been found to serve
formamides.
REFERENCES 1.
D. H. Lorenz and E. I. Becker, 3. Org. Chem., 28, 1707
2.
J. G. Noltes and M. J. Janssen, J. Organometal. Dergunov,
A. V. Pavlycheva,
V. F. Mironov 3.
R. Wesseley
V. D. Sheludyakov,
and V. P. Kosyukov,
(1963).
Chem., 1,
346 (1964);
I. A. Vostokov,
Zhur. Obshch. Khim., 42, 2501
and W. Swoboda, Monatsh.,
82, 621 (1961);
Yu. I.
Yu. I.Mushkin, (1972).
W. Ried and F. Miller,
Chem. Ber., 85, 470 (1962). 4.
D20 treatment sponding
5.
of the carbamoyl
silane resulted in the formation of the corre-
formamide -7a.
The nmr and ir spectra, and elemental
analyses of all new compounds
sistent with the assigned structures. 6.
S. Sugasawa and H. Shigehara,
J. Pharm. Sot. Japan, 62, 531 (1942).
7.
N. Fr&chl
8.
W. Walden, J. Amer. Chem. Sot., 19, 134 (1897).
9.
F. F. Blicke and C-J. Lu, ibid., 74, 3933
and P. Bomberg, Monatsh.,
48, 573 (1927).
(1953).
are con-
A NOVEL ROUTE TO FORMAMIDES REDUCTION
OF ISOCYANATES
PergamonPress. Printed in Great Britain,
AND THEIR DERIVATIVES.
VIA HYDROSILYLATION
CATALYZED
BY PALLADIUM
Iwao Ojima* and Shinichi Inaba Sagami Chemical
Research Center,
4-4-l Nishi-Onuma,
Sagamihara
229, JAPAN
and Yoichiro Nagai Department
of Chemistry,
Gunma University,
Kiryu, Gunma 376, JAPAN
(Receivedin Japan 31 August 1973; received in UK for publication25 September1973) Among the hydrides of the group IV elements, to react with isocyanates
across the carbon-nitrogen
organo(N-arylformamido)tin can be further converted distinctly
differnet
N-methylamines.' hydrides without
organotin hydrides
double bond to afford a tri-
1. or a triorgano(N-alkylcarbamoyl)tin to N-arylformamide
with triorganotin
from the reaction of isocyanates
The corresponding
are known
The formar
2.
hydride.
1
This is
with LiAlH4, which produces
reactions of silicon hydrides
have not been reported and in fact they lack reactivity
and germanium toward isoqanates
a proper catalyst. -
R3SnH
R3SnN(R')CH0
.->
R'NHCHO
(R' = Aryl)
+ R'NCo
-1,
R3Sn[-NHR' O
We found, however, in the presence
that a hydrosilylation
(R' = Hexyl)
2 of isocyanates
of PdC12 or Pd-C, and that the orientation
on the structure
of isocyanates.
of triethylsilane
does really occur
of the reaction
Now, we wish to report novel catalytic
with isocyanates,
depends reactiami
which furnishes a novel route to formamides
and their derivatives. M-Naphthyl
isocyanate was allowed to react with triethylsilane
sence of 0.1 Mel% of PdC12 or 10 % Pd-C at 80" for 2-3 hr.
4363
in the pre-
Distillation
of the
4x4
No. 44
reaction mixture amide
under reduced pressure
(3) in nearly quantitative
smoothly solvolyzed yield.
yield.
The silylformamide
to N-IX-naphthylformamide
The silylformamide
(2) quantitatively
gave N&-naphthyl-N-triethylsilylfonn-
(4) by methanol
2 was also converted
Et5SiH -
MeOH PdCQ
in quantitative
to N-IX-naphthyl-N-acetylformamide
by the reaction with an equimolar
N=C=O
3, thus obtained, was
acetyl chloride.
,
+
Bt9SiOMe
HNCHO
Et3Si-N-CHO
or Pd-C
2
Et9SiCl
+ CH9CONCHO I Phenyl isocyanate
and n-butyl isocyanate were hydrosilylated
fashion by triethylsilane tion of triethylsilane these isocyanates
in different
in the presence of PdC12 or 10 % Pd-C.
was observed across the carbon-nitrogen
in the opposite orientation,
Thus, the addi-
double bond of
and hitherto unknown
silanes, 6a (R = Ph, 95 %) and 6b (R = n Bu, 46 %), were obtained. of the carbamoyl
cleaving carbon-silicon
+
The reaction
silane a with acetyl chloride afforded N-acetylformamide
excellent yield, which might be formed through N-acetylcarbamoyl
R-N=C=O
carbamoyl
Et9SiH
2 in
silane 8 with
bond.
.--J PdCIZ or Pd-C
RNH-C-SiEt5 II 0
MeOH .->
RNHCHO
1
a [CH3CON(R)COSiEt3]
a:
R = Ph
b:
R = n-Bu
Jj
[HCi] I CH9CO(R)NCHO 2
+ Et9SiCl
No. t$J
4365
The nmr spectrum of the carbamoyl tautomerism observed
between
the structures
in the case of 2,
in the region
t
silane 6a suggests the existence of a 4 6A and 6B. A similar phenomenon was also -
i.e., the nmr spectrum of 7a displays
8.30-9.40.
After D20 treatment,
while two singlets remained, which are reasonably structures,
-7A and -7B.
The situation
Spectral data for these formamides
PhNH-C-SiEt3
.A
Compound
PhND-C-H
I
II
HO
0 6B -
3
__-
to C-H protons
of the
-
13c=o
NH or OH
I -7B
1670sh
___
and Their Derivatives5
(5, -CH=O
PhN=C-H DO
with Isocyanates
NMR
are listed in the Table
-
-7A
IR (cm-') 3NH
assigned
and their derivatives
1:l Adducts of Triethylsilane
mi?k2 -----
two broad singlets disappeared
is similar in the case of 6b and -* 7b
PhN=C-SiEt3
6A -
four signals
Bp('C/mm) -COCH,
7.05
or Mp(°C)
140/0.12
1630 4
3200
1655
8.63
8.63
141-142 (lit.,6 137.5)
5
___
1650
---
6a -
3270
1675
7.64 8.27
7a -
3240
1670
8.61 9.00
8.35 8.79
9a -
--_
1720 1685
_-_
9.40
10.60
1.94
79-81 go/o.45 45-46 (lit.,7 47.5)
2.05
55-57 (lit.,8 56-57)
6b -
3300
1670
8.12 8.17
7b -
3260
1660
7.00-7.44
82/1.0 8.03 7.83
130/20 (lit.,' 123/16)
9b -
--_
1725 1670
-__
9.17
2.41
135/15
No. 44
4966
Consequently,
the hydrosilylation
of isocyanates
may open a novel device for the preparation thesis of a new type of silicon compounds, ately formed silylated a good precursor
formamides
of N-acetyl
catalyzed
of formamides carbamoyl
and carbamoyl
by palladium
and also for the syn-
silanes, and the intermedi-
silanes have been found to serve
formamides.
REFERENCES 1.
D. H. Lorenz and E. I. Becker, 3. Org. Chem., 28, 1707
2.
J. G. Noltes and M. J. Janssen, J. Organometal. Dergunov,
A. V. Pavlycheva,
V. F. Mironov 3.
R. Wesseley
V. D. Sheludyakov,
and V. P. Kosyukov,
(1963).
Chem., 1,
346 (1964);
I. A. Vostokov,
Zhur. Obshch. Khim., 42, 2501
and W. Swoboda, Monatsh.,
82, 621 (1961);
Yu. I.
Yu. I.Mushkin, (1972).
W. Ried and F. Miller,
Chem. Ber., 85, 470 (1962). 4.
D20 treatment sponding
5.
of the carbamoyl
silane resulted in the formation of the corre-
formamide -7a.
The nmr and ir spectra, and elemental
analyses of all new compounds
sistent with the assigned structures. 6.
S. Sugasawa and H. Shigehara,
J. Pharm. Sot. Japan, 62, 531 (1942).
7.
N. Fr&chl
8.
W. Walden, J. Amer. Chem. Sot., 19, 134 (1897).
9.
F. F. Blicke and C-J. Lu, ibid., 74, 3933
and P. Bomberg, Monatsh.,
48, 573 (1927).
(1953).
are con-