Organic syntheses via transition metal complexes. 89.1 5-aza-1-metalla-1,3,5,7-octatetraenes and 2h-pyrrole and 2H-dihydroazete complexes from (1-alkynyl)carbene complexes (M = Cr, W) and alkenyl N-H imidates

Article abstract of DOI:10.1021/om9611057

Addition of alkenyl N-H. imidates RCH=CR¹C(OEt)=NH (8a-d; R, R¹ = Ph, Me, H) to (1-alkynyl)carbene complexes (CO)₅M=C(OEt)C≡CPh (6a,b; M = Cr, W) affords novel 5-aza-1-metalla-l,3,5,7-octatetraenes(CO) ₅M=C(OEt)CH=C(Ph)N=C(OEt)CR₁=CHR((Z)-9a-h; by Michael addition) together with 2,5-diethoxy-2H-pyrrole complexes 10a-h (by 3 + 2 cycloaddition) as well as 2,4-diethoxy-2H-dihydroazete complexes 11e-h (by 2 + 2 cycloaddition) in good overall yields. The product ratio 9:10:11 is strongly influenced by the nature of the metal (chromium or tungsten). Thus, formation of 5-aza-1-metalla-l,3,5,7-octatetraenes 9 is favored in the case of M = W, while 2H-dihydroazete complexes 11 are major products in the case of M = Cr. Compounds 9a-d undergo smooth cyclization at 80-90 °C to give 2,3-diethoxy-2H-pyrrole complexes 12a-d (which are regioisomers of 10a-d) in 86-93% yields, from which (metal-free) 2H-pyrroles 13a-d are generated on thermolysis at 110 °C. X-ray structure analyses are reported for the 5-aza-1-metalla-1,3,5,7-octatetraene 9b, the (regioisomeric) 2H-pyrrole complexes 10b and 12b, and the 2H-dihydroazete complex 11e.

Full text of DOI:10.1021/om9611057

Organometallics 1997, 16, 2571-2580
2571
Or ga n ic Syn th eses via Tr a n sition Meta l Com p lexes. 89.1
5-Aza -1-m eta lla -1,3,5,7-octa tetr a en es a n d 2H-P yr r ole a n d
2H-Dih yd r oa zete Com p lexes fr om (1-Alk yn yl)ca r ben e
Com p lexes (M ) Cr , W) a n d Alk en yl N-H Im id a tes
Rudolf Aumann,* Roland Fro¨hlich,† and Frank Zippel
Organisch-Chemisches Institut der Universita¨t Mu¨nster, Corrensstrasse 40,
D-48149 Mu¨nster, Germany
Received December 30, 1996X
Addition of alkenyl N-H imidates RCHdCR1C(OEt)dNH (8a -d ; R, R1 ) Ph, Me, H) to
(1-alkynyl)carbene complexes (CO)5MdC(OEt)CtCPh (6a ,b; M ) Cr, W) affords novel 5-aza-
1-metalla-1,3,5,7-octatetraenes (CO)5MdC(OEt)CHdC(Ph)NdC(OEt)CR1dCHR ((Z)-9a -h ;
by Michael addition) together with 2,5-diethoxy-2H-pyrrole complexes 10a -h (by 3 + 2
cycloaddition) as well as 2,4-diethoxy-2H-dihydroazete complexes 11e-h (by 2 + 2 cycload-
dition) in good overall yields. The product ratio 9:10:11 is strongly influenced by the nature
of the metal (chromium or tungsten). Thus, formation of 5-aza-1-metalla-1,3,5,7-octatet-
raenes 9 is favored in the case of M ) W, while 2H-dihydroazete complexes 11 are major
products in the case of M ) Cr. Compounds 9a -d undergo smooth cyclization at 80-90 °C
to give 2,3-diethoxy-2H-pyrrole complexes 12a -d (which are regioisomers of 10a -d ) in 86-
93% yields, from which (metal-free) 2H-pyrroles 13a -d are generated on thermolysis at
110 °C. X-ray structure analyses are reported for the 5-aza-1-metalla-1,3,5,7-octatetraene
9b, the (regioisomeric) 2H-pyrrole complexes 10b and 12b, and the 2H-dihydroazete complex
11e.
(1-Alkynyl)carbene complexes (CO)5MdC(OEt)CtCPh
of chromium and tungsten have been utilized in a broad
array of organic transformations.2 Recently, a highly
regioselective 3 + 2 cyclopentadiene annulation method
was reported, which is based on the addition of (1-
alkynyl)carbene complexes ()C3 unit) to cycloalkenyl
amines **CdC(NR2)*** ()C2 unit).3 The key step of
this reaction involves formation of 1-metalla-1,3,5-hexa-
trienes4 (CO)5MdC(OEt)CHdC(Ph)(**)CdC(NR2)*** by
Michael-type addition of the enamine to the CtC bond
of the (1-alkynyl)carbene complex,5 which subsequently
undergoes cyclization to cyclopentadiene complexes.
Formation of cyclopentadienes in a 3 + 2 fashion is
achieved also by reaction of alkynes R1CtCH ()C2 unit)
with 4-amino 1-chroma 1,3-dienes [)(enamino)carbene
complexes] (CO)5CrdC(OEt)CHdC(NR2)R ()C3 unit),6
but the regiochemistry of the “alkyne route” is different
from that of the “enamine route”, since 1-metalla-1,3,5-
hexatriene key intermediates (CO)5MdCR1CHdC(OEt)-
CHdC(NR2)R are generated with different regiochem-
istry by insertion of the alkyne R1CtCH into the MdC
bond of the 1-metalla-1,3-diene.7
We have extended studies on 1-metalla-1,3,5-hexa-
trienes to the nitrogen analogues 5-aza-1-metalla-1,3,5-
hexatrienes and also to 5-aza-1-metalla-1,3,5,7-octatet-
raenes (CO)5MdC(OEt)CHdC(Ph)NdC(OEt)CR1dCHR
(M ) Cr, W; R, R1 ) Me, Ph, H) and now wish to report
on the generation and thermal cyclization of the last
group of compounds.
5-Aza -1-m eta lla -1,3,5-h exa tr ien es a n d Im in iu m
Ca r bon ylm eta la tes
5-Aza-1-tungsta-1,3,5-hexatriene (CO)5WdC(NEt2)-
CMedC(Ph)NdCHPh (3) represents the first (fully char-
acterized) example of this class of carbene complexes.
Compound 3 was generated through chain extension by
addition of the electron-rich alkyne Et2NCtCMe (2) to
3-aza-1-tungsta-1,3-butadiene (CO)5WdC(OEt)NdCHPh
(1a ). The isomer (Z)-3 was shown to cyclize spontane-
ously and uniformly regiochemically to the 2H-pyrrole
complex 4 (Scheme 1), from which the corresponding
1H-pyrrole is generated by ligand disengagement.8
The electron-rich alkyne 2 is assumed to add as a
nucleophile directly to the carbene carbon atom of
compound 1a , thus generating the zwitterionic (non-
conjugated) iminium carbonylmetalate A, in which the
negative charge is stabilized by five oxygen atoms of the
(CO)5M moiety. The 5-aza-1-tungsta-1,3,5-hexatriene
3 is obtained from the zwitterion A by 1,3-migration of
the (CO)5M moiety. It should be noted that formation
* To whom correspondence should be addressed.
† X-ray structure analyses.
X Abstract published in Advance ACS Abstracts, May 1, 1997.
(1) Part 88: Yu, Z.; Aumann, R.; Fro¨hlich, R.; Hecht, J . J . Orga-
nomet. Chem., in press.
(2) For a review see: Aumann, R.; Nienaber, H. Adv. Organomet.
Chem., in press.
(3) (a) Aumann, R.; Meyer, A. G.; Fro¨hlich, R. Organometallics 1996,
5018-5027. (b) Meyer, A. G.; Aumann, R. Synlett 1995, 1011-1013.
(4) Aumann, R.; Heinen, H.; Dartmann, M.; Krebs, B. Chem. Ber.
1991, 124, 2343-2347.
(5) (a) Aumann, R.; Roths, K.; Grehl, M. Synlett 1993, 699-671. (b)
Aumann, R.; Ko¨ssmeier, M.; Roths, K.; Fro¨hlich, R. Synlett 1994,
1041-1044.
(6) (a) De Meijere, A. Pure Appl. Chem. 1996, 68, 61. (b) Duetsch,
M.; Lackmann, R.; Stein, F.; de Meijere, A. Synlett 1991, 324. (c) Flynn,
B. L.; Silviera, C. C.; de Meijere, A. Synlett 1995, 1007.
(7) Aumann, R.; Heinen, H.; Hinterding, P.; Stra¨ter, N.; Krebs, B.
Chem. Ber. 1991, 124, 1229-1236.
(8) Aumann, R.; Heinen, H.; Goddard, R.; Kru¨ger, C. Chem. Ber.
1991, 124, 2587-2593.
S0276-7333(96)01105-3 CCC: $14.00 © 1997 American Chemical Society

2572 Organometallics, Vol. 16, No. 12, 1997
Aumann et al.
Sch em e 1. P yr r ole F or m a tion via a
5-Aza -1-tu n gsta -1,3,5-h exa tr ien e Gen er a ted by
Ad d ition of a n Electr on -Rich Alk yn e to a
3-Aza -1-m eta lla -1,3-bu ta d ien e
) Ph, n-Pr, c-Pr, t-Bu). 5-Aza-1-chroma-1,3,5-hexatrienes
(CO)5CrdC(OEt)CHdC(R)NdCR1R2 thus generated were
reported to cyclize to 2H-pyrroles and (quite unexpect-
edly) also to 3(2H)-pyridinones by insertion of carbon
monoxide.14
Factors governing the regiochemistry of addition of
nitrogen nucleophiles to (1-alkynyl)carbene complexes
(CO)5MdC(OEt)CtCR (M ) Cr, W) are of current
interest, since they are crucial to the structure of the
organic product finally derived from such a reaction.
Strong influence on the regioselectivity is encountered
not only with different types of nitrogen nucleophiles
but also with different metals (chromium instead of
tungsten), different solvents, and different reaction
temperatures. Addition of N-lithio imines LiNdCR2
was found to occur exclusively at the CtC bond of the
chromium (1-alkynyl)carbene complex (CO)5CrdC-
(OEt)CtCR. The regioselectivity of this (fast) addition
could be explained by the assumption of an early transi-
tion state leading to preferential formation of the lith-
ium allenylmetalate Li[(OC)5CrC(OEt)dCdC(R)NdCR2]
rather than the lithium metalate Li[(OC)5CrC(OEt)-
(NdCR2)CtCR]. On the other hand, addition of alkenyl
N-alkyl imines R1NdCHCHdCHR2 (R1, R2 ) Me, n-Pr,
Bn, n-Pr, Ph) to chromium (1-alkynyl)carbene complexes
(CO)5CrdC(OEt)CtCR (R ) Ph, SiMe3, t-Bu) occurs
exclusively at the CrdC bond and leads to production
of chromium azepine complexes in 60-90% yields.15 The
regioselectivity of this (slow) reaction seems could be
controlled by a late transition state and thus would be
governed by the ease with which the iminium metalate
-(OC)5CrC(OEt)(R1N+dCHCHdCHR2)CtCR is pro-
duced, which (on the basis of estimates of spacial charge
separation) could be energetically favored over the
iminium metalate -(OC)5CrC(OEt)dCdCR(R1N+dCH-
CHdCHR2). It is interesting to note that 4 + 2
cycloadducts of alkenyl N-alkyl imines to the CtC bond
of (1-alkynyl)carbene complexes are minor byproducts
only in case of chromium but become major products
with the corresponding tungsten complexes, which is in
line with the trend expected for the higher steric
demand of a tungsten compared to a chromium atom.16
of compound 3 is assumed to follow a route significantly
different from the initial steps of a Do¨tz reaction, which
involve loss of a cis carbon monoxide ligand and
coordination of the alkyne to the metal atom prior to
insertion into the MdC bond.9 In principle, both the
carbene carbon atom and the terminal carbon atom of
the MdCNdCR2 unit are susceptible to nucleophilic
attack by an electron-rich alkyne. The regiochemistry
of addition of alkyne 2 to a 3-aza-1-metalla-1,3-butadi-
ene is strongly influenced by the nature of the metal
(M ) Cr, W) as well as by the substituents R on the
terminal carbon atom of the dCNdCR2 ligand. An
example for the latter case is represented by the highly
regioselective addition of alkyne 2 to the terminal
carbon atom of the chromium imidato compound
(CO)5CrdC(Ph)NdC(OEt)Ph.10
Reactions of the 3-aza-1-chroma-1,3-butadiene (CO)5-
CrdC(Ph)NdCHPh with nonpolarized or electron-poor
alkynes RCtCR1 (R ) Ph, Tol, n-Bu, SiMe3, CH2OMe,
CO2Me, Me; R1 ) H, Me, Ph) follow a route different
from that outlined above for an electron-rich alkyne.
Such reactions seem to be initiated by exchange of a
cis carbon monoxide ligand for an alkyne and subse-
quent insertion of the alkyne ligand into the MdC bond
to produce a chelated (3,4-η2)-5-aza-1-metalla-1,3,5-
hexatriene instead of an open-chain 5-aza-1-metalla-
1,3,5-hexatriene. Accordingly, 1H-pyrroles as well as
3-hydroxypyridines are formed by insertion of carbon
monoxide, as in the Do¨tz reaction.9,11,12 Interestingly,
2-aza-1-chroma-1,3-butadienes exhibit reversed but
highly selective heteroannulations with electron-rich
and electron-poor alkynes, respectively.13
2- vs 4-Ad d ition of Alk en yl N-H Im id a tes to
(1-Alk yn yl)ca r ben e Com p lexes
In an attempt to gain more information on the factors
governing the regiochemistry of the addition of nitrogen
nucleophiles to (1-alkynyl)carbene complexes 6a ,b (M
) Cr, W), we have extended the above-mentioned
studies on cycloadditions of alkenyl N-alkyl imides to
the addition of alkenyl N-H imidates 8. N-H Imidates
were chosen as substrates under the assumption that
structures of primary adducts might be traced back from
structures of the rearrangement products resulting from
N/C migration of a hydrogen atom.
An efficient approach to the formation of 5-aza-1-
metalla-1,3,5-hexatrienes other than by chain extension
of 3-aza 1-metalla 1,3-dienes through addition of alkynes
is based on addition of N-lithio imines LiNdCR1R2 (R1,
R2 ) Ph, c-Pr, anisyl) to the CtC bond of chromium
(1-alkynyl)carbene complexes (CO)5CrdC(OEt)CtCR (R
(9) (a) Do¨tz, K. H. Angew. Chem. 1975, 87, 672-673; Angew. Chem.,
Int. Ed. Engl. 1975, 14, 644-645. (b) Hofmann, P.; Ha¨mmerle, M.
Angew. Chem. 1989, 101, 940-942; Angew. Chem., Int. Ed. Engl. 1989,
28, 908-910. (c) Hoffman, P.; Ha¨mmerle, M.; Unfried, G. New J . Chem.
1991, 15, 769-789. (d) Gleichmann, M. M.; Do¨tz, K.-H., Hess, B. A. J .
Am. Chem. Soc. 1996, 118, 10551-10560.
Alkenyl N-H imidates 8a -d are most conveniently
prepared by alkylation of alkenyl N-H amides 5 with
triethyloxonium tetrafluoroborate.17 The iminium salt
7 which is generated in the first reaction step is very
(10) Aumann, R.; Heinen, H.; Kru¨ger, C.; Betz, P. Chem. Ber. 1990,
123, 599-604.
(11) (a) Aumann, R.; Heinen, H. J . Organomet. Chem. 1990, 399,
C1-C6. (b) Aumann, R.; Heinen, H. J . Organomet. Chem. 1990, 391,
C7-C11.
(14) Funke, F.; Duetsch, M.; Stein, F.; Noltemeyer, M.; de Meijere,
A. Chem. Ber. 1994, 127, 911-920.
(15) Barluenga, J .; Toma´s, M.; Rubio, E.; Lo´pez-Pelegr´ın, J .; Garc´ıa-
Granda, S.; Pertierra, P. J . Am. Chem. Soc. 1996, 118, 695-696.
(16) Aumann, R.; Yu, Z. Publication in preparation.
(17) Sato, K.; Miyamoto, O.; Inoue, S.; Ota, T. Synthesis 1982, 137-
138.
(12) Dragisich,V.; Murray, C. K.; Warner, B. P.; Wulff, W. D.; Yang,
D. C. J . Am. Chem. Soc. 1990, 112, 1251.
(13) Dragisich,V.; Wulff, W. D.; Hoogsteen, K. Organometallics 1990,
9, 2867.

5-Aza-1-metalla-1,3,5,7-octatetraenes
Organometallics, Vol. 16, No. 12, 1997 2573
Ta ble 1. P r od u ct Ra tios of Com p ou n d s 9-11, Selected 13C NMR Sh ifts (δ Va lu es, C6D6) a n d IR F r equ en cies
(cm -1) of 5-Aza -1-m eta lla -1,3,5,7-octa tetr a en es (Z)-9
9-11
M
R
R1
ratioa
yieldb
δ(C2)
δ(C4)
δ(C6)
δ(C8)
ν(CdN)
ν(CdC)
a
b
c
d
e
f
W
W
W
W
Cr
Cr
Cr
Cr
H
H
H
H
Me
H
H
H
Me
12:1:0
10:1:0
9:1:0
8:1:0
2:2:3
2:1:2
4:1:8
1:2:2
80
87
75
86
78
79
78
75
295.4
296.8
297.1
293.9
322.8
322.6
322.9
318.9
147.7
147.8
147.3
147.9
143.2
143.9
143.4
143.7
154.7
154.7
155.3
154.9
154.9
155.2
155.7
155.1
126.3
128.2
128.6
126.2
126.0
125.3
125.0
122.9
1677
1678
1680
1695
1674
1675
1660
1689
1612
1635
1638
1624
1611
1634
1620
1614
Me
Ph
H
H
Me
Ph
H
g
h
a
b
Product ratio 9:10:11. Total yield of complexes in percent.
Sch em e 2. Alk en yl N-H Im id a tes fr om Alk en yl
Sch em e 4. Mech a n istic Con sid er a tion of th e
Am id es
Im id a te Ad d ition to (1-Alk yn yl)ca r ben e Com p lexes
5, 7, 8
R
R1
a
b
c
d
H
H
H
H
Me
Me
Ph
H
Sch em e 3. Ad d u cts of Alk en yl N-H Im id a tes to
(1-Alk yn yl)ca r ben e Com p lexes
1,2-migration of the (CO)5M moiety to initially give an
intermediate D which subsequently undergoes a 1,3-
hydrogen migration, or they may form dihydroazete
complexes 11 via allene-type intermediates E generated
by 1,3-migration of the (CO)5M moiety, a subsequent
[2 + 2] cycloaddition, and a 1,4-hydrogen migration.
According to the product ratio summarized in Table
1, addition of alkenyl N-H imidates to the MdC bond
of (1-alkynyl)carbene compounds is favored for M ) Cr,
while addition to the CtC bond is preferred for M )
W.
Our results are in line with the regiochemistry
observed for cycloaddition reactions of alkenyl N-alkyl
imines to compounds 6a ,b. Nevertheless, it should be
strictly noted that the products 9-11 resulting from
addition of alkenyl N-H imidates 8 to compounds 6 have
structures completely different from those resulting
from addition of alkenyl N-alkyl imines to compounds
6a ,b. Interestingly, open-chain products 9 as well as
four- and five-membered N-heterocyclic rings 10 and 11
are obtained only with alkenyl N-H imidates, while six-
and seven-membered rings are generated only with
alkenyl N-alkyl imines.
sensitive to aqueous base but is readily transformed into
the imidate 8 with triethylamine in diethyl ether
(Scheme 2).
Reaction of alkenyl N-H imidates 8a -d with (1-
alkynyl)carbene complexes 6a ,b is complete within ca.
2 h at 20 °C and affords a mixture of three compounds
in good overall yields: red nonpolar 5-aza-1-metalla-
1,3,5,7-octatetraenes (Z)-9a -h by Michael addition,
yellow polar 2H-pyrrole complexes 10a -h by [3 + 2]
cycloaddition, and yellow polar dihydroazete complexes
11e-h by [2 + 2] cycloaddition (Scheme 3, Table 1).
Dihydroazete complexes 11 are obtained with chromium
but not with tungsten compounds (Table 1), while 5-aza-
1-metalla-1,3,5,7-octatetraenes 9 constitute the major
products in the case of tungsten compounds.
On the basis of the substitution pattern of the
products 9-11 two major reaction paths must be
distinguished in order to explain the formation of these
compounds. It appears that iminium carbonylmetalates
B and C, respectively, would play pivotal roles and must
be considered primary adducts of alkenyl imidates 8 to
(1-alkynyl)carbene complexes 6a ,b (Scheme 4). Com-
pounds B seem to act as precursors to 5-aza-1-metalla-
1,3,5-hexatrienes 9, which are generated therefrom by
1,3-hydrogen migration. Compounds C, on the other
hand, may either produce 2H-pyrrole complexes 10 by
Sp ectr oscop y
The spectroscopic data most characteristic of 5-aza-
1-metalla-1,3,5-hexatrienes 9 include 13C NMR chemical
shifts of the carbene carbon atom C2 (W, δ ca. 295; Cr,
δ ca. 322), C4 (W, δ ca. 147; Cr, δ ca. 143), C6 and C8,
as well as ν(CdN) and ν(CdC) frequencies in the IR
spectra in a narrow range (Table 1). Chromium and
tungsten compounds are easily distinguished by the 13
C
NMR shifts of C2 and C4 as well as by the ν(CtO)
pattern in the IR spectra (hexane solution), which
exhibits small but characteristic frequency differences
for the A1 band (e.g., tungsten complex 9a 2062 (20%),
1973 (5), 1938 cm-1(100) and chromium complex 9e

2574 Organometallics, Vol. 16, No. 12, 1997
Aumann et al.
Ta ble 2. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for 9b
W-C(4)
2.215(5)
1.325(6)
1.436(6)
1.374(6)
1.375(6)
N(7)-C(8)
C(8)-O(9)
C(8)-C(12)
C(12)-C(13)
1.269(6)
1.346(6)
1.452(7)
1.312(8)
O(3)-C(4)
C(4)-C(5)
C(5)-C(6)
C(6)-N(7)
C(4)-O(3)-C(2)
O(3)-C(4)-C(5)
O(3)-C(4)-W
122.2(4)
110.0(4)
129.8(4)
120.3(3)
129.7(4)
125.4(4)
125.7(4)
N(7)-C(8)-O(9)
N(7)-C(8)-C(12)
O(9)-C(8)-C(12)
C(8)-O(9)-C(10)
O(9)-C(10)-C(11)
C(13)-C(12)-C(8)
C(12)-C(13)-C(14)
120.0(4)
126.9(5)
113.1(4)
118.4(4)
108.1(5)
124.4(5)
125.6(6)
C(5)-C(4)-W
C(6)-C(5)-C(4)
C(5)-C(6)-N(7)
C(8)-N(7)-C(6)
Ta ble 3. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for 10b
W-N(1)
2.249(4)
1.304(5)
1.497(5)
1.397(5)
1.502(7)
C(2)-C(3)
C(21)-C(22)
C(3)-C(4)
C(4)-C(5)
C(5)-O(51)
1.534(6)
1.268(7)
1.330(6)
1.436(7)
1.322(5)
N(1)-C(5)
N(1)-C(2)
C(2)-O(24)
C(2)-C(21)
F igu r e 1. Molecular structure of the 5-aza-1-tungsta-
1,3,5,7-tetraene 9b.
C(5)-N(1)-C(2)
C(5)-N(1)-W
C(2)-N(1)-W
N(1)-C(2)-C(3)
C(4)-C(3)-C(2)
105.6(4)
129.1(3)
125.3(3)
104.6(3)
106.8(4)
C(3)-C(4)-C(5)
N(1)-C(5)-O(51)
N(1)-C(5)-C(4)
O(51)-C(5)-C(4)
108.5(4)
119.1(4)
114.3(4)
126.6(4)
Ta ble 4. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for 11e
Cr-N(1)
2.091(8)
C(3)-C(4)
C(4)-O(4)
C(4)-C(5)
C(3)-C(30)
1.577(14)
1.325(11)
1.54(2)
N(1)-C(2)
N(1)-C(4)
C(2)-O(2)
C(2)-C(3)
1.261(10)
1.540(12)
1.303(10)
1.507(13)
1.284(13)
C(2)-N(1)-C(4)
C(2)-N(1)-Cr
93.1(7)
137.0(6)
129.7(6)
126.0(8)
98.5(8)
135.5(8)
137.8(9)
139.3(9)
C(2)-C(3)-C(4)
C(3)-C(30)-C(31)
O(4)-C(4)-N(1)
O(4)-C(4)-C(5)
N(1)-C(4)-C(5)
O(4)-C(4)-C(3)
N(1)-C(4)-C(3)
C(5)-C(4)-C(3)
82.9(7)
129.0(9)
115.6(8)
109.3(9)
111.3(8)
120.9(9)
84.8(7)
C(4)-N(1)-Cr
N(1)-C(2)-O(2)
N(1)-C(2)-C(3)
O(2)-C(2)-C(3)
C(30)-C(3)-C(2)
C(30)-C(3)-C(4)
F igu r e 2. Molecular structure of tungsten 2,5-diethoxy-
2H-pyrrole complex 10b.
113.0(8)
C(6) ) 1.374(6) Å, C(6)-N(7) ) 1.375(6) Å, N(7)-C(8)
) 1.269(6) Å, C(8)-C(12) ) 1.452(7) Å, and C(12)-C(13)
) 1.312(8) Å, similar to that found for 2-alkoxy-1-tung-
sta-1,3,5-hexatrienes.18 The WdCCdC and NdCCdC
portions of the ligand are essentially planar (W-C(4)-
C(5)-C(6) ) -165.2(0.4)°, N(7)-C(8)-C(12)-C(13) )
179.6(0.6)°) but strongly distorted against each other
(C(5)-C(6)-N(7)-C(8) ) -83.7(0.7)°).
2053 (20%), 1974 (5), 1939 cm-1 (100)). Typical ν(CtO)
patterns are found also for 2H-pyrrole complexes (e.g.
tungsten compound 10a 2065 (10%), 1928 (100), 1903
cm-1 (30); chromium compound 10e 2062 (10%), 1934
(100), 1906 cm-1 (30)) and for dihydroazete complexes
11 (e.g. chromium complex 11e 2063 (10%), 1973 (5),
1939 (100), 1913 cm-1 (30); ν(CdN) 1671 cm-1).
The 2H-pyrrole ring of compound 10b is planar by
(0.003 Å within standard deviations. Bond distances
within the ring are alternating and correlate with the
distances found for a chromium 4-(diethylamino)-2-
ethoxy-3-methyl-2,5-diphenyl-2H-pyrrole complex.10
The four-membered ring of compound 11e is almost
planar (deviation from plane (0.03 Å), as has been
found also for the metal-free 1-azetine.19 The distance
N(1)-C(2) ) 1.261(10) Å is somewhat shorter than in
1-azetine (1.307 Å), and the distance C(3)-C(4) ) 1.577-
(14) Å is somewhat elongated, leading to a trapezoidal
ring. The Cr-N(1) distance 2.091(8) Å is similar to
Cr ysta l Str u ctu r e An a lyses of th e
5-Aza -1-m eta lla octa tetr a en e 9b,
2,5-Dieth oxy-2H-P yr r ole Com p lex 10b, a n d
2,4-Dieth oxy-2H-Dih yd r oa zete Com p lex 11e
Unambiguous structural assignment of the reaction
products is based on X-ray structure analyses of com-
pounds 9b, 10b, and 11e. For crystal data see the
Experimental Section. Selected bond lengths and angles
are given in Tables 2-4.
The plane defined by the atoms attached to the
carbene carbon atom of 9b bisects the angle between
two neighboring cis carbonyl groups, C(21)-W-C(4)-
C(5) ) 49.4(0.4)°. The WdCCdCNdCCdC backbone
of the ligand displays the alternating bond pattern
W-C(4) ) 2.215(5) Å, C(4)-C(5) ) 1.436(6) Å, C(5)-
(18) Aumann, R.; J asper, B.; La¨ge, M.; Krebs, B. Organometallics
1994, 13, 3510-3516.
(19) (a) Gieren, A.; Burger, K.; Thenn, W. Z. Naturforsch., B 1974,
29, 399. (b) Review on 1-azetines (2,3-dihydroazetes): Moore, J . A. In
The Chemistry of Heterocyclic Compounds; Hassner, A., Ed.; Wiley-
Interscience: New York, 1983; Vol. 42/2, pp 1-218.

5-Aza-1-metalla-1,3,5,7-octatetraenes
Organometallics, Vol. 16, No. 12, 1997 2575
F igu r e 3. Molecular structure of tungsten dihydroazete
complex 11e.
F igu r e 4. Molecular structure of tungsten 2,3-diethoxy-
2H-pyrrole complex 12b.
Sch em e 5. Th er m a l Cycliza tion of
5-Aza -1-tu n gsta -1,3,5,7-octa tetr a en es 9
Ta ble 5. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for 12b
W-N(1)
2.238(10)
1.333(14)
1.50(2)
1.38(2)
1.50(2)
C(2)-C(3)
C(3)-C(4)
C(3)-O(31)
C(4)-C(5)
C(5)-C(51)
1.51(2)
1.32(2)
1.32(2)
1.41(2)
1.50(2)
N(1)-C(5)
N(1)-C(2)
C(2)-O(21)
C(2)-C(24)
C(5)-N(1)-C(2)
C(5)-N(1)-W
102.8(11)
134.0(10)
123.0(8)
105.6(12)
134(2)
C(4)-C(3)-C(2)
O(31)-C(3)-C(2)
C(3)-C(4)-C(5)
N(1)-C(5)-C(4)
107.6(14)
118.2(14)
107.9(14)
115.8(13)
C(2)-N(1)-W
N(1)-C(2)-C(3)
C(4)-C(3)-O(31)
Cr ysta l Str u ctu r e An a lysis of
2,3-Dieth oxy-2H-P yr r ole Com p lex 12b
those in (CO)5Cr(NC5H5) (2.204(3) Å)20 and {4-[2-(di-
ethylamino)-1-methylethenyl]-3-ethoxy-2,3-dihydrophen-
ylazete}Cr(CO)5.21
The molecular structural of compound 12b was de-
termined also by an X-ray structure analysis. For
crystal data, see the Experimental Section. Selected
bond lengths and angles are given in Table 5.
The bond distances and bond angles of compound 12b
are very similar to those of compound 10b, except for
the longer distance N(1)-W ) 2.238(10) Å.
Cycliza tion of
5-Aza -1-m eta lla -1,3,5,7-octa tetr a en es
Formation of pyrroles via cyclization of 5-aza-1-
metalla-1,3,5-hexatrienes has been achieved previously
by the “alkyne route” (e.g. Scheme 1),8,11,12 and the
“imine route” (Scheme 4).14 Cyclization of 5-aza-1-
metalla-1,3,5,7-octatetraenes (Z)-9 might in principle
lead to formation of 2-alkenyl-2H-pyrrole complexes as
well as of 4H-azepine complexes. It has been found that
5-aza-1-tungsta-1,3,5,7-octatetraenes 9a -d undergo
smooth rearrangement at 80-90 °C to give 2-alkenyl-
2H-pyrrole complexes 12a -d in 86-93% yields. The
latter compounds afford (metal-free) 2-alkenyl-2H-pyr-
roles 13a -d at 110 °C by disengagement of W(CO)6
(Scheme 5). Formation of azepine derivatives has not
been observed under these conditions.
It should be noted that the 2-alkenyl-2H-pyrrole
complexes 12a -d (Scheme 5) are regioisomers of the
2-alkenyl-2H-pyrrole complexes 10a -d (Scheme 3). The
regioisomeric compounds can be easily distinguished by
NMR chemical shifts of C3, C4, C5, and 4-H. Structural
proof is based also on a X-ray analysis of the 2,3-
diethoxy-2H-pyrrole compound 12b.
Exp er im en ta l Section
All operations were carried out under an atmosphere of
argon. All solvents were dried and distilled prior to use. In
particular, dichloromethane was dried, distilled from P2O5, and
stored over 4 Å molecular sieves. Pentane refers to that
1
fraction boiling between 40 and 60 °C. All H (300 MHz) and
13C (75.5 MHz) NMR spectra were recorded on a Bruker ARX
300 instrument in CDCl3, unless otherwise indicated, and all
chemical shift values refer to δTMS 0.00. 13C NMR multiplici-
ties were determined by DEPT (distortionless enhancement
by polarization transfer) measurements. IR spectra were
recorded on a Biorad Digilab Division FTS-45 FT-IR spectro-
photometer. Elemental analyses were determined on a Per-
kin-Elmer 240 elemental analyzer. Analytical TLC plates,
Merck DC-Alufolien Kieselgel 60F240, were viewed by UV light
(254 nm) and stained by a 5% aqueous acidic ammonium
molybdate solution. Rf values refer to TLC tests. Chromato-
graphic purifications were performed on Merck Kieselgel 100.
2,6-Dieth oxy-4-p h en yl-1,1,1,1,1-p en ta ca r bon yl-5-a za -1-
tu n gsta -1,3,5,7-octa tetr a en e (9a ) a n d P en ta ca r bon yl(2,5-
dieth oxy-2-eth en yl-3-ph en yl-2H-pyr r ole-N)tu n gsten (10a).
Acrylamide 5a (92 mg, 1.30 mmol) and triethyloxonium
tetrafluoroborate (285 mg, 1.50 mmol) are reacted in 2 mL of
dry dichloromethane at 20 °C for 15 h with careful mixing by
efficient stirring (and/or ultrasonic radiation) and then added
(20) Cotton, F. A.; Darensbourg, D. J .: Fang, A.; Kolthammer, B.
W. S.; Reed, D.; Thompson, J . L. Inorg. Chem. 1981, 20, 4090.
(21) Aumann, R.; Kuckert, E.; Kru¨ger, C.; Goddard, R.; Angermund,
K. Chem. Ber. 1988, 121, 1475-1478.

2576 Organometallics, Vol. 16, No. 12, 1997
Aumann et al.
to pentacarbonyl(1-ethoxy-3-phenyl-2-propyn-1-ylidene)tung-
sten (6b; 482 mg, 1.00 mmol) in a 5 mL screw-top vessel. The
mixture is stirred for 2 min, and then triethylamine (202 mg,
2.00 mmol) in 2 mL of dichloromethane is added slowly with
stirring at 0 °C. Reaction progress is followed by TLC. After
the starting material is consumed completely (ca. 12 h at 20
°C), the solvent is removed in vacuo and the residue is
dissolved in 3 mL of toluene. Chromatography on silica gel
with pentane/diethyl ether (20:1) affords red 9a (429 mg, 74%,
Rf 0.5 in pentane, dark red crystals from pentane at -15 °C,
mp 79 °C); elution with pentane/diethyl ether (5:1) yields a
yellow fraction with 10a (35 mg, 6%, Rf 0.6 in pentane/diethyl
ether (1:1), yellow crystals from diethyl ether/pentane (1:5),
mp 126 °C).
for C22H21NO7W (595.3): C, 44.39; H, 3.56; N, 2.35. Found:
C, 44.60; H, 3.55; N, 2.27.
X-ray crystal structure analysis of 9b: formula C22H21
-
NO7W, Mr ) 595.25, 1.2 × 0.7 × 0.7 mm, a ) 9.209(1) Å, b )
9.731(1) Å, c ) 26.710(2) Å, V ) 2393.6(2) Å3, Fcalc ) 1.652 g
cm-3, µ ) 48.65 cm-1, T ) 223 K, empirical absorption cor-
rection via ψ-scan data (0.761 e C e 0.999), Z ) 4, orthorhom-
bic, space group P212121 (No. 19), λ ) 0.710 73 Å, ω/2θ scans,
5519 reflections collected (+h,(k,-l), (sin θ)/λ ) 0.62 Å-1
independent and 4545 observed reflections (I e 2σ(I)), 283
refined parameters, R ) 0.025, wR2 ) 0.063, maximum
(minimum) residual electron density 0.30 (-0.74) e Å-3, Flack
parameter -0.02(1), hydrogens calculated and riding. All data
were collected on a Enraf-Nonius MACH3 diffractometer.
Programs used: MolEN, SHELXS-86, SHELXL-93, XP.
, 4791
1
9a : H NMR (C6D6) δ 7.82 (1 H, s, 3-H), 7.66 and 7.05 (2:3
1
10b: H NMR (C6D6) δ 7.60 and 7.05 (2:3 H, m each, Ph),
H, m each, Ph), 5.80 and 5.00 (2:1 H, m each, H2CdCH), 4.52
(2 H, q, 2-OCH2), 3.98 (2 H, q, 6-OCH2), 1.05 (6 H, t, 2
CH2CH3); 13C NMR (C6D6) δ 295.4 (WdC), 204.3 and 199.4
[trans- and cis-CO, W(CO)5], 154.7 (Cq, NdC, C6), 147.7 [Cq,
CdC(N), C4], 138.0 (Cq, i-C Ph), 131.1, 129.2, and 127.9 (1:2:
2, CH each, Ph), 128.0 (CH, C7), 125.0 (CH, C3), 126.3 (CH2,
C8), 79.5 (2-OCH2), 63.0 (6-OCH2), 14.5 and 14.4 (2 CH2CH3);
IR (hexane, cm-1) 2061.5 (20), 1973.0 (5), 1938.1 (100) [ν-
(CtO)], 1677.3 [ν(CdN)], 1612.4 [ν(CdC)]; MS (70 eV, m/ e
(%)) 184W, 581 (5) [M+], 553 (15), 525 (60), 497 (40), 469 (30),
441 (50) [M+ - 5 CO], 412 (100). Anal. Calcd for C21H19NO7W
(581.2): C, 43.40; H, 3.29; N, 2.41. Found: C, 43.60; H, 3.37;
N, 2.36.
6.22 (1 H, dq, 3J ) 15.5 and 6.5 Hz, dCHMe), 6.05 (1 H, s,
4-H), 5.05 (1 H, d, 3J ) 15.5 Hz, HCdCHMe), 3.50 (2 H, q,
5-OCH2), 3.30 and 2.80 (1 H each, diastereotopic 2-OCH2), 1.55
(3 H, d, 3J ) 6.5 Hz, dCHCH3), 1.15 (3 H, t, 5-OCH2CH3), 1.05
(3 H, t, 2-OCH2CH3); 13C NMR (C6D6) δ 203.4 and 199.4 [trans-
and cis-CO, W(CO)5], 173.9 (Cq, CdN, C5), 166.9 (Cq, C3), 131.2
and 129.6 (CHdCHMe), 131.2, 129.0, and 127.3 (1:2:2, CH
each, Ph), 130.5 (Cq, i-C Ph), 111.5 (CH, C4), 103.3 (Cq, C2),
67.8 (5-OCH2), 59.4 (2-OCH2), 17.8 (dCHCH3), 14.5 and 14.4
(2 CH2CH3); IR (hexane, cm-1) 2064.3 (10), 1925.5 (100), 1903.1
(30) [ν(CtO)], 1614.2 [ν(CdC)]; MS (70 eV, m/ e (%)) 184W, 595
(25) [M+], 567 (10), 511 (20), 455 (100) [M+ - 5 CO], 426 (60),
271 (60) [ligand+], 256 (70), 241 (60), 214 (60), 198 (60), 69
(100). Anal. Calcd for C22H21NO7W (595.3): C, 44.39; H, 3.56;
N, 2.35. Found: C, 44.54; H, 3.58; N, 2.54.
1
10a : H NMR (C6D6) δ 7.80 and 7.45 (2:3 H, m each, Ph),
5.92 (1 H, s, 4-H), 5.82 and 5.25 (1:2 H, m each, H2CdCH),
3.45 (2 H, m, diastereotopic 5-OCH2), 3.30 and 2.80 (1 H each,
diastereotopic 2-OCH2), 1.16 (3 H, t, 5-OCH2CH3), 1.05 (3 H,
t, 2-OCH2CH3); 13C NMR (CDCl3) δ 203.4 and 198.8 [trans-
and cis-CO, W(CO)5], 174.1 (Cq, CdN, C5), 166.8 [Cq, C3], 135.8
(2-CHdCH2), 131.2, 128.9, and 127.2 (1:2:2, CH each, Ph),
129.9 (Cq, i-C Ph), 120.1 (dCH2), 111.7 (CH, C4), 103.0 (Cq,
C2), 68.2 (5-OCH2), 59.4 (2-OCH2), 14.8 and 14.5 (2 CH2CH3);
IR (hexane, cm-1) 2065.2 (10), 1928.3 (100), 1903.2 (30) [ν-
(CtO)], 1615.0 [ν(CdC)]; MS (70 eV, m/ e (%)) 184W, 581 (25)
[M+], 553 (10), 525 (5), 497 (20), 469 (5), 441 (100) [M+ - 5
CO], 257 (60) [ligand+], 228 (60), 200 (100). Anal. Calcd for
X-ray crystal structure analysis of 10b: formula C22H21
-
NO7W, Mr ) 595.25, 0.7 × 0.7 × 0.3 mm, a ) 11.894(1) Å, b )
17.050(2) Å, c ) 12.033(1) Å, â ) 101.60(1)°, V ) 2390.4(4) Å3,
Fcalc ) 1.654 g cm-3, µ ) 48.72 cm-1, T ) 293 K, empirical
absorption correction via ψ-scan data (0.682 e C e 0.999), Z
) 4, monoclinic, space group P21/c (No. 14), λ ) 0.710 73 Å,
ω/2θ scans, 5069 reflections collected (-h,+k,(l), (sin θ)/λ )
0.62 Å-1, 4835 independent and 3605 observed reflections (I
e 2 σ(I)), 283 refined parameters, R ) 0.029, wR2 ) 0.069,
maximum (minimum) residual electron density 1.13 (-0.78)
e Å-3, hydrogens calculated and riding. All data were collected
on a Enraf-Nonius MACH3 diffractometer. Programs used:
MolEN, SHELXS-86, SHELXL-93, XP.
C
21H19NO7W (581.2): C, 43.40; H, 3.29; N, 2.41. Found: C,
43.40; H, 3.33; N, 2.51.
2,6-Dieth oxy-4-p h en yl-1,1,1,1,1-p en ta ca r bon yl-5-a za -1-
tu n gsta -1,3,5,7-n on a tetr a en e (9b) a n d P en ta ca r bon yl-
[2,5-dieth oxy-2-(1-pr open yl)-3-ph en yl-2H-pyr r ole-N]tu n g-
sten (10b). Crotonamide 5b (111 mg, 1.30 mmol) is succes-
sively reacted with triethyloxonium tetrafluoroborate (285 mg,
1.50 mmol), pentacarbonyl(1-ethoxy-3-phenyl-2-propyn-1-
ylidene)tungsten (6b; 482 mg, 1.00 mmol), and triethylamine
(202 mg, 2.00 mmol) as described above until the reaction is
complete (ca. 2 h at 20 °C). Chromatography on silica gel
(column 20 × 2 cm) with pentane/diethyl ether affords the red
compound 9b (470 mg, 79%, Rf 0.7 in pentane/diethyl ether
(10:1), dark red crystals from pentane at -15 °C, mp 101 °C),
elution with pentane/diethyl ether (5:1) yields a yellow fraction
with 10b (48 mg, 8%, Rf 0.8 in diethyl ether, yellow crystals
from diethyl ether/pentane (1:5), mp 121 °C).
2,6-Diet h oxy-4,8-d ip h en yl-1,1,1,1,1-p en t a ca r b on yl-5-
a za -1-tu n gsta -1,3,5,7-octa tetr a en e (9c) a n d P en ta ca r bo-
n yl[2,5-d ieth oxy-2-(2-p h en yl-1-eth en yl)-3-p h en yl-2H-p yr -
r ole-N]tu n gsten (10c). Cinnamamide 5c (191 mg, 1.30
mmol) is successively reacted with triethyloxonium tetrafluo-
roborate (285 mg, 1.50 mmol), pentacarbonyl(1-ethoxy-3-
phenyl-2-propyn-1-ylidene)tungsten (6b; 482 mg, 1.00 mmol),
and triethylamine (202 mg, 2.00 mmol) as described above
until the reaction is complete (ca. 2 h at 20 °C). Chromatog-
raphy on silica gel (column 20 × 2 cm) with pentane/diethyl
ether affords the red compound 9c (443 mg, 67%, Rf 0.6 in
pentane/diethyl ether (10:1), dark red crystals from pentane
at -15 °C, mp 126 °C); elution with pentane/diethyl ether (5:
1) yields a yellow fraction with 10c (50 mg, 8%, Rf 0.8 in diethyl
ether, yellow crystals from diethyl ether/pentane (1:5)).
1
1
9b: H NMR (C6D6) δ 7.96 (1 H, s, 3-H), 7.80 and 7.03 (2:3
9c: H NMR (C6D6) δ 7.96 (1 H, s, 3-H), 7.80 and 7.03 (2:3
H, m each, Ph), 6.50 (1 H, dq, 3J ) 15 and 6 Hz, dCHMe),
3
H, m each, 4-Ph), 7.50 (1 H, d, J ) 16 Hz, dCHPh), 7.10 and
3
6.90 (2:3 H, m each, 8-Ph), 6.45 (1 H, d, 3J ) 16 Hz,
CHdCHPh), 4.55 (2 H, q, 2-OCH2), 4.15 (2 H, q, 6-OCH2), 1.20
and 1.05 (3 H each, t each, 2 CH2CH3); 13C NMR (C6D6) δ 297.1
(WdC), 204.0 and 198.9 [trans- and cis-CO, W(CO)5], 155.3
(Cq, NdC, C6), 147.3 [Cq, CdC(N), C4], 140.8 (CH, C7), 138.0
(Cq, i-C 4-Ph), 135.0 (Cq, i-C 8-Ph); 131.0, 129.3, and 127.9 (1:
2:2, CH each, 4-Ph), 130.3, 129.1, and 128.0 (1:2:2, CH each,
8-Ph), 128.6 (CH, C8), 114.3 (CH, C3), 79.2 (2-OCH2), 63.0 (6-
OCH2), 14.7 and 14.2 (2 CH2CH3); IR (hexane, cm-1) 2061.2
(10), 1972.3 (1), 1940.6 (100) [ν(CtO)], 1680.4 [ν(CdN)], 1638.1
[ν(CdC)]; MS (70 eV, m/ e (%)) 184W, 657 (10) [M+], 629 (15),
5.68 (1 H, d, J ) 15 Hz, CHdCHMe), 4.58 (2 H, q, 2-OCH2),
4.05 (2 H, q, 6-OCH2), 1.30 (3 H, d, 3J ) 6 Hz, dCHCH3), 1.05
(6 H, t, 2 CH2CH3); 13C NMR (C6D6) δ 296.8 (WdC), 204.0 and
199.0 [trans- and cis-CO, W(CO)5], 154.7 (Cq, NdC, C6), 147.8
[Cq, CdC(N), C4], 140.1 (CH, C7), 137.9 (Cq, i-C Ph), 130.8,
129.1, and 127.8 (1:2:2, CH each, Ph), 128.2 (CH, C8), 119.0
(CH, C3), 79.1 (2-OCH2), 62.7 (6-OCH2), 17.7 (dCHCH3), 14.6
and 14.1 (2 CH2CH3); IR (hexane, cm-1) 2060.8 (20), 1972.3
(5), 1938.5 (100) [ν(CtO)], 1677.8 [ν(CdN)], 1635.2 [ν(CdC)];
MS (70 eV, m/ e (%)) 184W, 595 (5) [M+], 567 (25), 539 (60),
511 (10), 483 (30), 455 (100) [M+ - 5 CO], 426 (60). Anal. Calcd

5-Aza-1-metalla-1,3,5,7-octatetraenes
Organometallics, Vol. 16, No. 12, 1997 2577
601 (60), 573 (10), 545 (30), 517 (100) [M+ - 5 CO], 488 (60),
ylidene)chromium (6a ; 350 mg, 1.00 mmol), and triethylamine
(202 mg, 2.00 mmol) are successively reacted as described
above until the reaction is complete (ca. 2 h at 20 °C).
Chromatography on silica gel with pentane/diethyl ether (20:
1) affords red 9e (103 mg, 23%, Rf 0.3 in pentane, dark red
crystals from pentane at -15 °C, mp 74 °C); elution with
pentane/diethyl ether (10:1) yields a yellow fraction with 11e
(157 mg, 35%, Rf 0.6 in pentane/diethyl ether (1:1), pale yellow
crystals from pentane, mp 123 °C) and 10e (90 mg, 20%, Rf
0.5 in pentane/diethyl ether (1:1), dark yellow crystals from
pentane).
333 (30) [ligand+], 304 (80), 289 (100). Anal. Calcd for C27H23
-
NO7W (657.3): C, 49.34; H, 3.53; N, 2.13. Found: C, 48.99;
H, 3.45; N, 2.14.
10c: 1H NMR (C6D6): δ 7.70 and 7.05 (2:3 H, m each, 3-Ph),
3
7.25 and 7.00 (2:3 H, m each, CHdCHC6H5), 7.42 (1 H, d, J
) 15.5, dCHPh), 6.09 (1 H, s, 4-H), 5.80 (1 H, d, 3J ) 15.5 Hz,
HCdCHPh), 3.50 (2 H, q, 5-OCH2), 3.28 and 2.85 (1 H each,
diastereotopic 2-OCH2), 1.12 (3 H, t, 5-OCH2CH3), 1.03 (3 H,
t, 2-OCH2CH3); 13C NMR (C6D6) δ 203.3 and 199.3 [trans- and
cis-CO, W(CO)5], 174.3 (Cq, CdN, C5), 166.8 (Cq, C3), 136.0
(Cq, i-C, dCHC6H5), 134.9 and 128.3 (CHdCHPh), 131.3, 129.1,
and 127.3 (1:2:2, CH each, 5-Ph), 130.4 (Cq, i-C 5-Ph), 129.0,
128.0, and 127.8 (1:2:2, CH each, dCHC6H5), 111.9 (CH, C4),
103.6 (Cq, C2), 68.0 (5-OCH2), 59.6 (2-OCH2), 14.6 and 14.5 (2
CH2CH3); IR (hexane, cm-1) 2064.7 (10), 1925.3 (100), 1902.4
(30) [ν(CtO)], 1614.8 [ν(CdC)]; MS (70 eV, m/ e (%)) 184W, 657
(15) [M+], 629 (10), 601 (5), 517 (100) [M+ - 5 CO], 488 (60),
1
9e: H NMR (C6D6) δ 7.82 (1 H, s, 3-H), 7.62 and 7.03 (2:3
H, m each, Ph), 5.80 and 5.00 (2:1 H, m each, H2CdCH), 4.60
(2 H, q, 2-OCH2), 3.99 (2 H, q, 6-OCH2), 1.05 (6 H, t, 2
CH2CH3); 13C NMR (C6D6) δ 322.8 (CrdC), 224.5 and 218.1
[trans- and cis-CO, Cr(CO)5], 154.9 (Cq, NdC, C6), 143.2 [Cq,
CdC(N), C4], 137.8 (Cq, i-C Ph), 130.7, 129.0, and 128.3 (1:2:
2, CH each, Ph), 126.0 (CH2, C8), 125.3 (CH, C7), 125.0 (CH,
C3), 76.4 (2-OCH2), 62.7 (6-OCH2), 14.7 and 14.0 (2 CH2CH3);
IR (hexane, cm-1) 2052.7 (20), 1974.0 (5), 1939.2 (100) [ν-
(CtO)], 1673.9 [ν(CdN)], 1611.1 [ν(CdC)]; MS (70 eV, m/ e
(%)) 449 (10) [M+], 431 (5), 393 (20), 365 (20), 337 (30), 309
(80) [M+ - 5 CO], 280 (60), 242 (70), 228 (100). Anal. Calcd
for C21H19CrNO7 (449.4): C, 56.13; H, 4.26; N, 3.12. Found:
C, 55.99; H, 4.33; N, 2.98.
333 (60) [ligand+], 304 (100), 276 (60). Anal. Calcd for C27H23
-
NO7W (657.3): C, 49.34; H, 3.53; N, 2.13. Found: C, 49.32;
H, 3.65; N, 2.26.
2,6-Diet h oxy-7-m et h yl-4-p h en yl-1,1,1,1,1-p en t a ca r b o-
n yl-5-a za -1-tu n gsta -1,3,5,7-octa tetr a en e (9d ) a n d P en ta -
car bon yl[2,5-dieth oxy-2-(2-pr open yl)-3-ph en yl-2H-pyr r ole-
N]tu n gsten (10d ). Methacrylamide 5d (111 mg, 1.30 mmol)
is successively reacted with triethyloxonium tetrafluoroborate
(285 mg, 1.50 mmol), pentacarbonyl(1-ethoxy-3-phenyl-2-pro-
pyn-1-ylidene)tungsten (6b; 482 mg, 1.00 mmol), and triethy-
lamine (202 mg, 2.00 mmol) as described above until the
reaction is complete (ca. 2 h at 20 °C). Chromatography on
silica gel (column 20 × 2 cm) with pentane/diethyl ether affords
the red compound 9d (452 mg, 76%, Rf 0.7 in pentane/diethyl
ether (10:1), dark red crystals from pentane at -15 °C, mp 91
°C); elution with pentane/diethyl ether (5:1) yields a yellow
fraction with 10d (60 mg, 10%, Rf 0.8 in diethyl ether, yellow
crystals from diethyl ether/pentane (1:5), mp 132 °C).
1
10e: H NMR (C6D6) δ 7.70 and 7.15 (2:3 H, m each, Ph),
6.05 (1 H, s, 4-H), 5.80 and 5.20 (1:2 H, m each, H2CdCH),
3.50 (2 H, m, diastereotopic 5-OCH2), 3.30 and 2.80 (1 H each,
diastereotopic 2-OCH2), 1.16 (3 H, t, 5-OCH2CH3), 1.05 (3 H,
t, 2-OCH2CH3); 13C NMR (C6D6) δ 222.6 and 216.6 [trans- and
cis-CO, Cr(CO)5], 174.6 (Cq, CdN, C5), 167.2 [Cq, C3], 136.2
(2-CHdCH2); 131.0, 128.9, and 127.2 (1:2:2, CH each, Ph),
129.9 (Cq, i-C Ph), 119.9 (dCH2), 112.4 (CH, C4), 103.0 (Cq,
C2), 67.6 (5-OCH2), 59.3 (2-OCH2), 14.7 and 14.5 (2 CH2CH3);
IR (hexane, cm-1) 2062.1 (10), 1934.0 (100), 1905.7 (30) [ν-
(CtO)], 1614.2 [ν(CdC)].
1
9d : H NMR (C6D6) δ 7.65 (1 H, s, 3-H), 7.60 and 7.03 (2:3
11e: 1H NMR (C6D6) δ 7.32, 7.10, and 7.05 (2:2:1 H, m each,
Ph), 6.02 (1 H, s, dCH), 5.86 (1 H, d, 3J ) 17 Hz, trans-
HCdCH), 5.64 (1 H, dd, 3J ) 17 and 10 Hz, HCdCH2), 5.29 (1
H, d, 3J ) 10 Hz, cis-HCdCH), 3.79 (2 H, m, 4-OCH2), 3.50
and 3.10 (1 H each, diastereotopic 2-OCH2), 1.18 and 1.03 (3
H each, t each, OCH2CH3 each); 13C NMR (C6D6) δ 222.1 and
215.9 [trans- and cis-CO, Cr(CO)5], 177.7 (Cq, CdN, C4), 136.1
(2-CHdCH2), 133.0 and 132.9 (Cq each, i-C Ph and C3), 131.0,
130.5, and 129.0 (2:1:2, CH each, Ph), 121.1 (dCH2), 120.2
(dCHPh), 95.1 (Cq, C2), 67.4 (4-OCH2), 59.3 (2-OCH2), 14.8
and 14.6 (2 CH2CH3); IR (hexane, cm-1) 2063.0 (10), 1973.4
(5), 1938.9 (100), 1913.0 (30) [ν(CtO)], 1671.4 [ν(CdN)]; MS
(70 eV, m/ e (%)) 449 (85) [M+], 421 (20), 365 (40), 337 (85),
309 (80) [M+ - 5 CO], 265 (80), 257 (60) [ligand+], 183 (60),
142 (80), 96 (100). Anal. Calcd for C21H19CrNO7 (449.4): C,
56.13; H, 4.26; N, 3.12. Found: C, 56.23; H, 4.35; N, 3.20.
H, m each, Ph), 5.40 and 4.90 (1 H each, s each, dCH2), 4.60
(2 H, q, 2-OCH2), 3.90 (2 H, q, 6-OCH2), 1.59 (3 H, s, dCCH3),
1.10 and 1.05 (3 H each, t each, 2 CH2CH3); 13C NMR (C6D6)
δ 293.9 (WdC), 204.3 and 199.3 [trans- and cis-CO, W(CO)5],
154.9 (Cq, NdC, C6), 147.9 [Cq, CdC(N), C4], 137.9 (Cq, i-C
Ph), 136.1 (Cq, dCMe), 131.1, 129.3, and 127.8 (1:2:2, CH each,
Ph), 126.2 (CH2, C8), 122.8 (CH, C3), 79.1 (2-OCH2), 63.6 (6-
OCH2), 19.5 (dCCH3), 14.9 and 14.2 (2 CH2CH3); IR (hexane,
cm-1) 2060.5 (20), 1971.8 (5), 1938.1 (100) [ν(CtO)], 1695.0
[ν(CdN)], 1624.2 [ν(CdC)]; MS (70 eV, m/ e (%)) 184W, 595 (5)
[M+], 567 (25), 539 (60), 511 (10), 483 (30), 455 (100) [M+ - 5
CO], 426 (100). Anal. Calcd for C22H21NO7W (595.3): C, 44.39;
H, 3.56; N, 2.35. Found: C, 44.66; H, 3.66; N, 2.56.
1
10d : H NMR (C6D6) δ 7.65 and 7.05 (2:3 H, m each, Ph),
6.20 and 5.30 (1 H each, s each, dCH2), 6.12 (1 H, s, 4-H),
3.60 (2 H, q, 5-OCH2), 3.30 and 2.85 (1 H each, diastereotopic
2-OCH2), 1.22 (3 H, s, dCCH3), 1.15 and 1.05 (3 H each, t each,
2-OCH2CH3); 13C NMR (C6D6) δ 203.2 and 199.3 [trans- and
cis-CO, W(CO)5], 174.9 (Cq, CdN, C5), 166.5 (Cq, C3), 139.9
(dCMe), 131.4, 129.1, and 127.0 (1:2:2, CH each, Ph), 130.5
(Cq, i-C Ph), 119.0 (dCH2), 112.8 (CH, C4), 104.5 (Cq, C2), 68.0
(5-OCH2), 59.5 (2-OCH2), 17.5 (dCCH3), 14.5 and 14.4 (2
CH2CH3); IR (hexane, cm-1) 2064.7 (10), 1926.3 (100), 1904.7
(30) [ν(CtO)], 1612.2 [ν(CdC)]; MS (70 eV, m/ e (%)) 184W, 595
(20) [M+], 567 (10), 511 (15), 455 (100) [M+ - 5 CO], 426 (60),
271 (60) [ligand+], 256 (70), 241 (60), 214 (60), 198 (60), 69
(100). Anal. Calcd for C22H21NO7W (595.3): C, 44.39; H, 3.56;
N, 2.35. Found: C, 44.42; H, 3.67; N, 2.62.
2,6-Dieth oxy-4-p h en yl-1,1,1,1,1-p en ta ca r bon yl-5-a za -1-
ch r om a -1,3,5,7-octa tetr a en e (9e), P en ta ca r bon yl(2,5-d i-
eth oxy-2-eth en yl-3-ph en yl-2H-pyr r ole-N)ch r om iu m (10e),
an d P en tacar bon yl(3-ben zyliden e-2-eth en yl-2,4-dieth oxy-
2,3-d ih yd r oa zete-N)ch r om iu m (11e). Acrylamide 5a (92
mg, 1.30 mmol), triethyloxonium tetrafluoroborate (285 mg,
1.50 mmol), pentacarbonyl(1-ethoxy-3-phenyl-2-propyn-1-
X-ray crystal structure analysis of 11e: formula C21H19
-
CrNO7, Mr ) 449.37, 0.3 × 0.2 × 0.1 mm, a ) 9.533(2) Å, b )
10.768(3) Å, c ) 12.614(3) Å, R ) 110.20(2)°, â ) 96.37(2)°, γ
) 110.12(2)°, V ) 1101.6(5) Å3, Fcalc ) 1.355 g cm-3, µ ) 5.59
cm-1, T ) 223 K, empirical absorption correction via ψ-scan
data (0.981 e C e 0.999), Z ) 2, triclinic, space group P1h, (No.
2), λ ) 0.710 73 Å, ω/2θ scans, 2193 reflections collected
((h,+k,(l), (sin θ)/λ ) 0.48 Å-1, 2046 independent and 1347
observed reflections (I e 2σ(I)), 273 refined parameters, R )
0.071, wR2 ) 0.192, maximum (minimum) residual electron
density 0.64 (-0.63) e Å-3, hydrogens calculated and riding.
All data were collected on a Enraf-Nonius MACH3 diffracto-
meter. Programs used: MolEN, SHELXS-86, SHELXL-93,
XP.
2,6-Dieth oxy-4-p h en yl-1,1,1,1,1-p en ta ca r bon yl-5-a za -1-
ch r om a -1,3,5,7-n on a tetr a en e (9f), P en ta ca r bon yl[2,5-d i-
et h oxy-2-(1-p r op en yl)-3-p h en yl-2H-p yr r ole-N]ch r om i-
u m (10f), a n d P en t a ca r b on yl[3-b en zylid en e-2,4-d iet h -
oxy-2-(1-p r op en yl)-2,3-d ih yd r oa zete-N)ch r om iu m (11f).
Crotonamide 5b (111 mg, 1.30 mmol) is successively reacted

2578 Organometallics, Vol. 16, No. 12, 1997
Aumann et al.
with triethyloxonium tetrafluoroborate (285 mg, 1.50 mmol),
pentacarbonyl(1-ethoxy-3-phenyl-2-propyn-1-ylidene)chro-
mium (6a ; 350 mg, 1.00 mmol), and triethylamine (202 mg,
2.00 mmol) as described above until the reaction is complete
(ca. 2 h at 20 °C). Chromatography on silica gel (column 20
× 2 cm) with pentane/diethyl ether affords the red compound
9f (144 mg, 31%, Rf 0.7 in pentane/diethyl ether (10:1), dark
red crystals from pentane at -15 °C, mp 85 °C); elution with
pentane/diethyl ether (5:1) yields a yellow fraction consisting
of a 1:2 mixture of isomeric compounds 10f and 11f (222 mg,
48%, Rf 0.2 in pentane/diethyl ether (10:1), fractional crystal-
lization from diethyl ether affords 11f in bright yellow crystals,
while 10f is accumulated in the supernatant).
ether/pentane (10:1), from which yellow crystals of 11g are
obtained by fractional crystallization).
1
9g: H NMR (C6D6) δ 7.98 (1 H, s, 3-H), 7.79 and 6.85 (2:3
3
H, m each, 4-Ph), 7.55 (1 H, d, J ) 16 Hz, dCHPh), 7.20 and
7.10 (2:3 H, m each, 8-Ph), 6.45 (1 H, d, 3J ) 16 Hz,
CHdCHPh), 4.70 (2 H, q, 2-OCH2), 4.12 (2 H, q, 6-OCH2), 1.20
and 1.15 (3 H each, t each, 2 CH2CH3); 13C NMR (C6D6) δ 322.9
(CrdC), 224.5 and 218.0 [trans- and cis-CO, Cr(CO)5], 155.7
(Cq, NdC, C6), 143.4 [Cq, CdC(N), C4], 140.7 (CH, C7), 138.0
(Cq, i-C 4-Ph), 135.0 (Cq, i-C 8-Ph); 130.7, 129.0, and 127.9 (1:
2:2, CH each, 4-Ph); 130.1, 129.1, and 128.0 (1:2:2, CH each,
8-Ph), 125.0 (CH, C8), 114.0 (CH, C3), 76.4 (2-OCH2), 62.0 (6-
OCH2), 14.8 and 14.2 (2 CH2CH3); IR (hexane, cm-1) 2052.5
(10), 1974.6 (1), 1940.7 (100) [ν(CtO)], 1659.9 [ν(CdN)], 1619.8
[ν(CdC)]; MS (70 eV, m/ e (%)) 525 (5) [M+], 497 (5), 469 (10),
441 (10), 413 (30), 385 (50) [M+ - 5 CO], 333 (30) [ligand+],
304 (80), 289 (60), 228 (100). Anal. Calcd for C27H23CrNO7
(525.5): C, 61.71; H, 4.41; N, 2.67. Found: C, 62.19; H, 4.23;
N, 2.82.
1
9f: H NMR (C6D6) δ 7.82 (1 H, s, 3-H), 7.70 and 7.03 (2:3
H, m each, Ph), 6.45 (1 H, dq, 3J ) 15 and 6 Hz, dCHMe),
3
5.69 (1 H, d, J ) 15 Hz, CHdCHMe), 4.80 (2 H, q, 2-OCH2),
4.03 (2 H, q, 6-OCH2), 1.30 (3 H, d, 3J ) 6 Hz, dCHCH3), 1.05
(6 H, t, 2 CH2CH3); 13C NMR (C6D6) δ 322.6 (CrdC), 224.6
and 218.4 [trans- and cis-CO, Cr(CO)5], 155.2 (Cq, NdC, C6),
143.9 [Cq, CdC(N), C4], 140.1 (CH, C7), 138.0 (Cq, i-C Ph),
130.7, 129.4, and 128.4 (1:2:2, CH each, Ph), 125.3 (CH, C8),
119.2 (CH, C3), 76.8 (2-OCH2), 62.7 (6-OCH2), 17.7 (dCHCH3),
14.8 and 14.2 (2 CH2CH3); IR (hexane, cm-1) 2052.5 (20),
1974.5 (5), 1938.6 (100) [ν(CtO)], 1674.7 [ν(CdN)], 1633.9 [ν-
(CdC)]; MS (70 eV, m/ e (%)) 463 (10) [M+], 435 (5), 407 (10),
379 (10), 351 (30), 323 (100) [M+ - 5 CO], 294 (40), 279 (60).
Anal. Calcd for C22H21CrNO7 (463.4): C, 57.02; H, 4.57; N,
3.02. Found: C, 57.26; H, 4.68; N, 3.14.
10g: 1H NMR (C6D6) δ 7.70 and 7.05 (2:3 H, m each, 3-Ph),
7.23 and 7.03 (2:3 H, m each, CHdCHC6H5), 7.42 and 6.98 (1
3
H each, d each, J ) 15.5 Hz, CHdCHPh), 6.20 (1 H, s, 4-H),
3.50 (2 H, q, 5-OCH2), 3.20 and 3.00 (1 H each, diastereotopic
2-OCH2), 1.35 (3 H, t, 5-OCH2CH3), 0.95 (3 H, t, 2-OCH2CH3);
13C NMR (C6D6) δ 222.3 and 214.5 [trans- and cis-CO, Cr(CO)5],
176.0 (Cq, CdN, C5), 167.8 (Cq, C3), 136.0 (Cq, i-C, dCH-C6H5),
134.8 and 128.4 (CHdCHPh), 131.3, 129.1, and 127.2 (1:2:2,
CH each, 5-Ph), 130.4 (Cq, i-C 5-Ph), 129.0, 128.0, and 127.8
(1:2:2, CH each, dCHC6H5), 117.2 (CH, C4), 103.6 (Cq, C2),
67.0 (5-OCH2), 61.5 (2-OCH2), 14.6 and 14.5 (2 CH2CH3); IR
(hexane, cm-1) 2062.1 (10), 1934.0 (100), 1905.7 (30) [ν(CtO)],
1614.2 [ν(CdC)].
1
10f: H NMR (C6D6) δ 7.60 and 7.03 (2:3 H, m each, Ph),
3
6.23 (1 H, dq, J ) 15 and 6 Hz, dCHMe), 5.84 (1 H, s, 4-H),
5.05 (1 H, d, 3J ) 15.5 Hz, HCdCHMe), 3.50 (2 H, q, 5-OCH2),
3.30 and 2.60 (1 H each, diastereotopic 2-OCH2), 1.65 (3 H, d,
3J ) 6.5 Hz, dCHCH3), 1.25 (3 H, t, 5-OCH2CH3), 1.05 (3 H,
t, 2-OCH2CH3); 13C NMR (C6D6) δ 222.5 and 216.4 [trans- and
cis-CO, Cr(CO)5], 174.7 (Cq, CdN, C5), 167.4 (Cq, C3), 132.6
and 129.6 (CHdCHMe), 131.2, 129.0, and 127.3 (1:2:2, CH
each, Ph), 130.5 (Cq, i-C Ph), 111.5 (CH, C4), 103.3 (Cq, C2),
67.5 (5-OCH2), 59.5 (2-OCH2), 17.9 (dCHCH3), 14.5 and 14.4
(2 CH2CH3); IR (hexane, cm-1) 2061.9 (10), 1934.8 (100), 1907.2
(30) [ν(CtO)].
1
11g: H NMR (C6D6) δ 7.50-7.20 (10 H, m, 2 Ph), 7.11 (1
3
H, d, J ) 15.5 Hz, dCHPh), 6.50 (1 H, s, dCHPh), 6.12 (1 H,
d, 3J ) 15.5 Hz, HCdCHPh), 4.68 (2 H, m, 4-OCH2), 3.58
and 3.30 (1 H each, diastereotopic 2-OCH2), 1.56 (3 H, t,
4-OCH2CH3), 1.30 (3 H, t, 2-OCH2CH3); 13C NMR (CDCl3) δ
221.9 and 215.1 [trans- and cis-CO, Cr(CO)5], 174.3 (Cq, CdN,
C4), 135.9, 134.5, and 133.2 (Cq each, 2 i-C Ph and C3), 135.2
and 127.8 (CHdCHPh), 130.2, 129.7, 128.8, 128.5, 126.9, and
128.8 (2:1:2:2:2:1, CH each, 2 Ph), 119.9 (dCHPh), 95.1 (Cq,
C2), 57.5 (4-OCH2), 59.2 (2-OCH2), 15.1 and 14.6 (2 CH2CH3);
IR (hexane, cm-1) 2062.8 (10), 1938.4 (100), 1913.9 (30) [ν-
(CtO)], 1671.0 [ν(CdN)]; MS (70 eV, m/ e (%)) 525 (5) [M+],
413 (30), 385 (50) [M+ - 5 CO], 333 (90) [ligand+], 304 (100).
Anal. Calcd for C27H23CrNO7 (525.5): C, 61.71; H, 4.41; N,
2.67. Found: C, 62.06; H, 4.56; N, 2.87.
11f: 1H NMR (C6D6) δ 7.35, 7.12, and 7.00 (2:2:1 H, m each,
3
Ph), 6.23 (1 H, dq, J ) 15 and 6 Hz, dCHMe), 5.95 (1 H, s,
3
dCHPh), 5.23 (1 H, d, J ) 15 Hz, CHdCHMe), 3.70 (2 H, q,
4-OCH2), 3.50 and 3.10 (1 H each, diastereotopic 2-OCH2), 1.57
(3 H, d, dCCH3), 1.19 and 1.00 (3 H each, t each, 2 OCH2CH3);
13C NMR (C6D6) δ 222.1 and 216.0 [trans- and cis-CO, Cr(CO)5],
177.4 (Cq, CdN, C4), 133.8 and 133.2 (Cq each, i-C Ph and
C3), 132.8 (CHd), 130.5, 129.7, and 129.0 (2:1:2, CH each, Ph),
128.6 (dCHMe), 119.5 (dCHPh), 95.2 (Cq, C2), 67.2 (4-OCH2),
59.2 (2-OCH2), 17.7 (dCCH3), 14.9 and 14.7 (2 CH2CH3); IR
(hexane, cm-1) 2061.8 (10), 1937.5 (100), 1912.4 (30) [ν(CtO)],
1670.5 [ν(CdN)]; MS (70 eV, m/ e (%)) 463 (25) [M+], 435 (10),
407 (10), 379 (5), 351 (60), 323 (100) [M+ - 5 CO], 271 (50)
[ligand+], 242 (60). 228 (100). Anal. Calcd for C22H21CrNO7
(463.4): C, 57.02; H, 4.57; N, 3.02. Found: C, 56.88; H, 4.70;
N, 3.17.
2,6-Diet h oxy-7-m et h yl-4-p h en yl-1,1,1,1,1-p en t a ca r b o-
n yl-5-a za -1-ch r om a -1,3,5,7-octa tetr a en e (9h ), P en ta ca r -
bon yl[2,5-d ieth oxy-2-(2-p r op en yl)-3-p h en yl-2H-p yr r ole-
N]ch r om iu m (10h ), a n d P en ta ca r bon yl[3-ben zylid en e-
2,4-d ie t h oxy-2-(2-p r op e n yl)-2,3-d ih yd r oa ze t e -N )ch r o-
m iu m (11h ). Methacrylamide 5d (111 mg, 1.30 mmol) is suc-
cessively reacted with triethyloxonium tetrafluoroborate (285
mg, 1.50 mmol), pentacarbonyl(1-ethoxy-3-phenyl-2-propyn-
1-ylidene)chromium (6a ; 350 mg, 1.00 mmol), and triethyl-
amine (202 mg, 2.00 mmol) as described above until the
reaction is complete (ca. 2 h at 20 °C). Chromatography on
silica gel (column 20 × 2 cm) with pentane/diethyl ether affords
the red compound 9h (69 mg, 15%, Rf 0.7 in pentane/diethyl
ether (10:1), dark red crystals from pentane at -15 °C); elution
with pentane/diethyl ether (5:1) yields a yellow fraction
consisting of a 1:1 mixture of isomeric compounds 10h and
11h (278 mg, 60%, Rf 0.2 in pentane/diethyl ether (10:1),
fractional crystallization from diethyl ether affords 11h as
bright yellow crystals, while 10h is accumulated in the
supernatant).
2,6-Diet h oxy-4,8-d ip h en yl-1,1,1,1,1-p en t a ca r b on yl-5-
a za -1-ch r om a -1,3,5,7-octa tetr a en e (9g), P en ta ca r bon yl-
[2,5-dieth oxy-2-(2-ph en yl-1-eth en yl)-3-ph en yl-2H-pyr r ole-
N]ch r om iu m (10g), a n d P en ta ca r bon yl[3-ben zylid en e-
2,4-d ie t h oxy-2-(2-p r op e n yl)-2,3-d ih yd r oa ze t e -N )ch r o-
m iu m (11g). Cinnamamide 5c (191 mg, 1.30 mmol) is suc-
cessively reacted with triethyloxonium tetrafluoroborate (285
mg, 1.50 mmol), pentacarbonyl(1-ethoxy-3-phenyl-2-propyn-
1-ylidene)chromium (6a ; 350 mg, 1.00 mmol), and triethyl-
amine (202 mg, 2.00 mmol) as decribed above until the reaction
is complete (ca. 2 h at 20 °C). Chromatography on silica gel
(column 20 × 2 cm) with pentane/diethyl ether affords the red
compound 9g (126 mg, 24%, Rf 0.6 in pentane/diethyl ether
(10:1), dark red crystals from pentane at -15 °C, mp 121 °C);
elution with pentane/diethyl ether (5:1) yields a yellow fraction
of a 1:8 mixture of 10g and 11g (284 mg, 54%, Rf 0.2 in diethyl
1
9h : H NMR (C6D6) δ 7.68 (1 H, s, 3-H), 7.60 and 7.00 (2:3
H, m each, Ph), 5.30 and 4.92 (1 H each, s each, dCH2), 4.70
(2 H, q, 2-OCH2), 3.88 (2 H, q, 6-OCH2), 1.58 (3 H, s, dCCH3),
1.20 and 1.02 (3 H each, t each, 2 CH2CH3); 13C NMR (C6D6)
δ 318.9 (CrdC), 224.6 and 218.4 [trans- and cis-CO, Cr(CO)5],

5-Aza-1-metalla-1,3,5,7-octatetraenes
Organometallics, Vol. 16, No. 12, 1997 2579
155.1 (Cq, NdC, C6), 143.7 [Cq, CdC(N), C4], 137.9 (Cq, i-C
Ph), 136.0 (Cq, dCMe), 130.8, 129.1, and 127.7 (1:2:2, CH each,
Ph), 122.9 (CH2, C8), 122.5 (CH, C3), 76.2 (2-OCH2), 63.2 (6-
OCH2), 19.3 (dCCH3), 14.9 and 14.0 (2 CH2CH3); IR (hexane,
cm-1) 2052.2 (20), 1974.1 (5), 1938.0 (100) [ν(CtO)], 1689.0
[ν(CdN)], 1613.7 [ν(CdC)]; MS (70 eV, m/ e (%)) 463 (10) [M+],
435 (5), 407 (10), 379 (10), 351 (30), 323 (100) [M+ - 5 CO],
294 (40), 279 (60). Anal. Calcd for C22H21CrNO7 (463.4): C,
57.02; H, 4.57; N, 3.02. Found: C, 57.22; H, 4.63; N, 2.88.
(Cq, i-C Ph), 130.9, 128.6, and 126.9 (1:2:2, CH each, Ph), 116.5
(dCH2), 94.1 (Cq, C4), 100.5 (Cq, C2), 67.5 (3-OCH2), 59.7 (2-
OCH2), 15.9 and 14.1 (2 CH2CH3).
P en ta ca r bon yl[2,3-d ieth oxy-2-(1-p r op en yl)-5-p h en yl-
2H-p yr r ole-N]tu n gsten (12b) a n d 2,3-Dieth oxy-2-(1-p r o-
p en yl)-5-p h en yl-2H-p yr r ole (13b). 2,6-Diethoxy-4-phenyl-
1,1,1,1,1-pentacarbonyl-5-aza-1-tungsta-1,3,5,7-nonatetra-
ene (9b; 297 mg, 0.50 mmol) in 2 mL of toluene is heated to
90 °C for 5.5 h. Reaction progress is followed by TLC.
Chromatography on silica gel with pentane/diethyl ether
affords the pale yellow compound 12b (267 mg, 90%, Rf 0.2 in
pentane/diethyl ether (10:1), yellow crystals from pentane at
-15 °C, mp 110 °C). Thermolysis of compound 9b at 110 °C
for 6 h affords the metal-free pyrrole 13b together with
W(CO)6.
1
10h : H NMR (C6D6) δ 7.55 and 7.03 (2:3 H, m each, Ph),
6.10 and 5.25 (1 H each, s each, dCH2), 5.97 (1 H, s, 4-H),
3.42 (2 H, q, 5-OCH2), 3.23 and 2.77 (1 H each, diastereotopic
2-OCH2), 1.18 (3 H, s, dCCH3), 1.16 and 1.12 (3 H each, t each,
2-OCH2CH3); 13C NMR (C6D6) δ 222.5 and 216.4 [trans- and
cis-CO, Cr(CO)5], 174.9 (Cq, CdN, C5), 167.4 (Cq, C3), 139.9
(dCMe), 131.5, 129.5, and 127.2 (1:2:2, CH each, Ph), 130.5
(Cq, i-C Ph), 118.8 (dCH2), 113.1 (CH, C4), 104.2 (Cq, C2), 67.5
(5-OCH2), 59.5 (2-OCH2), 17.5 (dCCH3), 14.6 and 14.4 (2
CH2CH3); IR (hexane, cm-1) 2061.9 (10), 1934.8 (100), 1907.2
(30) [ν(CtO)]; MS (70 eV, m/ e (%)) MS (70 eV, m/ e (%)) 463
1
3
12b: H NMR (C6D6) δ 7.23 (5 H, m, Ph), 6.38 (1 H, dq, J
) 15.5 and 6.5 Hz, dCHMe), 5.19 (1 H, d, 3J ) 15.5 Hz,
HCdCHMe), 4.80 (1 H, s, 4-H), 3.40 and 3.10 (1 H each,
diastereotopic 2-OCH2), 3.35 (2 H, q, 3-OCH2), 1.80 (3 H, d, 3J
) 6.5 Hz, dCHCH3), 1.30 (3 H, t, 3-OCH2CH3), 0.90 (3 H, t,
2-OCH2CH3); 13C NMR (C6D6) δ 202.3 and 199.2 [trans- and
cis-CO, W(CO)5], 184.0 (Cq, CdN, C5), 180.2 (Cq, C3), 137.6
(Cq, i-C Ph), 132.2 and 127.6 (CHdCHMe), 130.9, 129.6, and
127.0 (1:2:2, CH each, Ph), 104.7 (Cq, C2), 100.1 (CH, C4), 68.4
(3-OCH2), 60.0 (2-OCH2), 17.9 (dCHCH3), 14.9 and 13.7 (2
CH2CH3); IR (hexane, cm-1) 2064.5 (10), 1931.2 (100), 1905.8
(30) [ν(CtO)], 1625.5 [ν(CdC)]; MS (70 eV, m/ e (%)) 184W, 595
(25) [M+], 567 (10), 511 (20), 455 (100) [M+ - 5 CO], 426 (60),
271 (20) [ligand+], 241 (70), 227 (90), 198 (100). Anal. Calcd
for C22H21NO7W (595.3): C, 44.39; H, 3.56; N, 2.35. Found:
C, 44.60; H, 3.56; N, 2.48.
(15) [M+], 435 (10), 407 (10), 379 (5), 351 (5), 323 (100) [M+
5 CO], 271 (90) [ligand+], 242 (100). Anal. Calcd for C22H21
-
-
CrNO7 (463.4): C, 57.02; H, 4.57; N, 3.02. Found: C, 57.26;
H, 4.62; N, 3.14.
11h : 1H NMR (C6D6) δ 7.25, 7.07, and 6.95 (2:2:1 H, m each,
Ph), 6.23 and 5.25 (1 H each, s each, dCH2), 5.86 (1 H, s,
dCHPh), 3.65 (2 H, q, 4-OCH2), 3.50 and 3.12 (1 H each,
diastereotopic 2-OCH2), 1.47 (3 H, s, dCCH3), 1.03 and 0.91
(3 H each, t each, 2 OCH2CH3); 13C NMR (C6D6) δ 221.9 and
215.8 [trans- and cis-CO, Cr(CO)5], 177.9 (Cq, CdN, C4), 140.0
(dCMe), 133.2 and 132.8 (Cq each, i-C Ph and C3), 130.3, 130.7,
and 129.4 (1:2:2, CH each, Ph), 119.6 (dCH2), 119.8 (CH,
dCHPh), 96.4 (Cq, C2), 67.3 (4-OCH2), 59.2 (2-OCH2), 18.4
(dCCH3), 14.9 and 14.4 (2 CH2CH3); IR (hexane, cm-1) 2061.9
(10), 1934.8 (100), 1907.2 (30) [ν(CtO)], 1670.5 [ν(CdN)]; MS
(70 eV, m/ e (%)) 463 (25) [M+], 435 (10), 407 (10), 379 (5), 351
(60), 323 (100) [M+ - 5 CO], 271 (50) [ligand+], 242 (60). Anal.
Calcd for C22H21CrNO7 (463.4): C, 57.02; H, 4.57; N, 3.02.
Found: C, 57.17; H, 4.72; N, 2.98.
X-ray crystal structure analysis of 12b: formula C22H21
-
NO7W, Mr ) 595.25, 0.5 × 0.2 × 0.2 mm, a ) 10.440(2) Å, b )
25.870(6) Å, c ) 9.203(3) Å, â ) 109.47(12)°, V ) 2343.4(10)
Å3, Fcalc ) 1.687 g cm-3, µ ) 49.69 cm-1, T ) 293 K, empirical
absorption correction via ψ-scan data (0.823 e C e 0.999), Z
) 4, monoclinic, space group P21/c (No. 14), λ ) 0.710 73 Å,
ω/2θ scans, 4213 reflections collected ((h,+k,+l), (sin θ)/λ )
0.59 Å-1, 3949 independent and 1497 observed reflections (I
e 2σ(I)), 283 refined parameters, R ) 0.054, wR2 ) 0.067,
maximum (minimum) residual electron density 0.74 (-0.89)
e Å-3, hydrogens calculated and riding. All data were collected
on a Enraf-Nonius MACH3 diffractometer. Programs used:
MolEN, SHELXS-86, SHELXL-93, XP.
P en t a ca r b on yl(2,3-d iet h oxy-2-et h en yl-5-p h en yl-2H -
p yr r ole-N)tu n gsten (12a ) a n d 2,3-Dieth oxy-2-eth en yl-5-
p h en yl-2H-p yr r ole (13a ). 2,6-Diethoxy-4-phenyl-1,1,1,1,1-
pentacarbonyl-5-aza-1-tungsta-1,3,5,7-octatetraene (9a ; 290
mg, 0.50 mmol) in 2 mL of toluene is heated to 80 °C for 6 h.
Reaction progress is followed by TLC. Chromatography on
silica gel with pentane/diethyl ether affords the pale yellow
compound 12a (270 mg, 93%, Rf 0.3 in pentane/diethyl ether
(10:1), yellow crystals from pentane at -15 °C, mp 110 °C).
Thermolysis of compound 9a at 110 °C for 6 h affords the
metal-free pyrrole 13a together with W(CO)6.
1
13b: H NMR (C6D6) δ 8.05 and 7.20 (2:3 H, m each, Ph),
3
3
6.32 (1 H, dq, J ) 15.5 and 6.5 Hz, dCHMe), 5.88 (1 H, d, J
) 15.5 Hz, HCdCHMe), 5.42 (1 H, s, 4-H), 3.60 and 3.30 (1 H
each, diastereotopic 2-OCH2), 3.55 (2 H, q, 3-OCH2), 1.55 (3
3
H, d, J ) 6.5 Hz, dCHCH3), 1.20 (3 H, t, 3-OCH2CH3), 1.05
(3 H, t, 2-OCH2CH3); 13C NMR (C6D6) δ 181.5 (Cq, CdN, C5),
176.1 (Cq, C3), 135.2 (Cq, i-C Ph), 130.9, 129.6, and 127.0 (1:
2:2, CH each, Ph), 129.0 (CHdCHMe), 100.1 (CH, C4), 93.7
(Cq, C2), 67.5 (3-OCH2), 59.5 (2-OCH2), 17.9 (dCHCH3), 15.9
and 14.2 (2 CH2CH3); IR (film, cm-1) 1728.4 (10) [ν(CdN)],
1625.5 (100) [ν(CdC)]; MS (70 eV, m/ e (%)) 271 (40) [M+], 242
(70), 227 (30), 214 (40), 198 (40), 186 (30), 69 (100).
1
12a : H NMR (C6D6) δ 7.20 and 7.18 (3:2 H, m each, Ph),
5.96 and 5.42 (1:2 H, m each, H2CdCH), 4.75 (1 H, s, 4-H),
3.22 (2 H, m, diastereotopic 3-OCH2), 3.40 and 3.05 (1 H each,
diastereotopic 2-OCH2), 1.30 (3 H, t, 3-CH2CH3), 0.90 (3 H, t,
2-CH2CH3); 13C NMR (C6D6) δ 202.1 and 199.1 [trans- and cis-
CO, W(CO)5], 184.4 (Cq, CdN, C5), 180.0 (Cq, C3), 137.4 (Cq,
i-C Ph), 134.2 (2-CHdCH2), 130.8, 128.1, and 126.9 (1:2:2, CH
each, Ph), 120.8 (dCH2), 104.7 (Cq, C2), 100.5 (Cq, C4), 68.4
(3-OCH2), 60.1 (2-OCH2), 14.8 and 13.7 (2 CH2CH3); IR
(hexane, cm-1) 2065.6 (10), 1932.4 (100), 1906.9 (30) [ν(CtO)],
1628.0 [ν(CdC)]; MS (70 eV, m/ e (%)) 184W, 581 (25) [M+], 553
(10), 525 (1), 497 (10), 469 (5), 441 (100) [M+ - 5 CO], 257
(30) [ligand+], 228 (80), 213 (60). Anal. Calcd for C21H19NO7W
(581.2): C, 43.40; H, 3.29; N, 2.41. Found: C, 43.10; H, 3.21;
N, 2.60.
P en ta ca r bon yl[2,3-d ieth oxy-2-(2-p h en yl-1-eth en yl)-5-
p h en yl-2H-p yr r ole-N]tu n gsten (12c) a n d 2,3-Dieth oxy-
2-(2-p h en yl-1-eth en yl)-5-p h en yl-2H-p yr r ole (13c). 2,6-
Diethoxy-4,8-diphenyl-1,1,1,1,1-pentacarbonyl-5-aza-1-tungsta-
1,3,5,7-octatetraene (9c; 329 mg, 0.50 mmol) in 2 mL of toluene
is heated to 90 °C for 5.5 h. Reaction progress is followed by
TLC. Chromatography on silica gel with pentane/diethyl ether
affords the pale yellow compound 12c (283 mg, 86%, R
f 0.2 in
pentane/diethyl ether (10:1), yellow crystals from pentane at
-15 °C). Thermolysis of compound 9c at 110 °C for 6 h affords
the metal-free pyrrole 13c together with W(CO)6.
1
13a : H NMR (C6D6) δ 8.10 and 7.21 (2:3 H, m each, Ph),
3
6.15 (1 H, dd, J ) 17.5 and 10.5 Hz, HCdCH2), 5.88 (1 H, d,
3
3
3J ) 17.5 Hz, trans dCH2), 5.42 (1 H, s, 4-H), 5.20 (1 H, d, J
12c: 1H NMR (C6D6) δ 7.28 (1 H, d, J ) 15.5 Hz, dCHPh),
) 10.5, cis dCH2), 3.55 (2 H, m, diastereotopic 3-OCH2), 3.70
and 3.20 (1 H each, diastereotopic 2-OCH2), 1.20 (3 H, t,
3-OCH2CH3), 1.00 (3 H, t, 2-OCH2CH3); 13C NMR (C6D6) δ
181.1 (Cq, CdN, C5), 172.4 (Cq, C3), 136.5 (2-CHdCH2), 135.0
7.23 (5 H, m, Ph), 7.20 and 6.90 (2:3 H m each, dCHC6H5),
5.95 (1 H, d, 3J ) 15.5 Hz, HCdCHPh), 4.80 (1 H, s, 4-H),
3.55 and 3.10 (1:3 H, 2 diastereotopic OCH2), 1.30 (3 H, t,
3-OCH2CH3), 0.75 (3 H, t, 2-OCH2CH3); 13C NMR (C6D6) δ

2580 Organometallics, Vol. 16, No. 12, 1997
Aumann et al.
202.3 and 199.0 [trans- and cis-CO, W(CO)5], 184.4 (Cq, CdN,
C5), 180.0 (Cq, C3), 137.4 (Cq, i-C 5-Ph), 136.0 (Cq, i-C, dCH-
C6H5), 135.8 and 124.5 (CHdCHPh), 131.2, 129.5, and 127.2
(1:2:2, CH each, 5-Ph), 130.9, 128.9, and 128.2 (1:2:2, CH each,
dCHC6H5), 104.9 (Cq, C2), 100.3 (CH, C4), 68.4 (3-OCH2), 60.1
(2-OCH2), 14.8 and 13.6 (2 CH2CH3); IR (hexane, cm-1) 2064.7
(10), 1931.2 (100), 1906.7 (30) [ν(CtO)], 1624.6 [ν(CdC)]; MS
(70 eV, m/ e (%)) 184W, 657 (25) [M+], 573 (10), 517 (100) [M+
- 5 CO], 488 (60), 333 (20) [ligand+], 304 (70), 289 (100), 260
(90). Anal. Calcd for C27H23NO7W (657.3): C, 49.34; H, 3.53;
N, 2.13. Found: C, 49.26; H, 3.42; N, 1.99.
cis-CO, W(CO)5], 185.4 (Cq, CdN, C5), 179.7 (Cq, C3), 137.6
(Cq, i-C Ph), 137.5 (CH, dCMe), 130.6, 129.1, and 126.8 (1:2:
2, CH each, Ph), 119.0 (dCH2), 105.9 (Cq, C2), 101.5 (CH, C4),
68.5 (3-OCH2), 60.2 (2-OCH2), 17.5 (dCCH3), 14.8 and 13.7 (2
CH2CH3); IR (hexane, cm-1) 2064.5 (10), 1931.2 (100), 1908.1
(30) [ν(CtO)], 1628.6 [ν(CdC)]; MS (70 eV, m/ e (%)) 184W, 595
(25) [M+], 567 (10), 511 (20), 455 (100) [M+ - 5 CO], 426 (60),
271 (20) [ligand+], 242 (70), 214 (90), 57 (100). Anal. Calcd
for C22H21NO7W (595.3): C, 44.39; H, 3.56; N, 2.35. Found:
C, 44.62; H, 3.43; N, 2.50.
1
13d : H NMR (C6D6) δ 8.10 and 7.21 (2:3 H, m each, Ph),
1
13c: H NMR (C6D6) δ 8.15 and 7.20 (2:3 H, m each, Ph),
5.80 and 5.00 (1 H each, s each, dCH2), 5.35 (1 H, s, 4-H),
3.70 and 3.45 (1 H each, diastereotopic 2-OCH2), 3.55 (2 H, q,
3-OCH2), 1.95 (3 H, s, dCCH3), 1.20 (3 H, t, 3-OCH2CH3), 1.00
(3 H, t, 2-OCH2CH3); 13C NMR (C6D6) δ 181.0 (Cq, CdN, C5),
172.6 (Cq, C3), 142.8 (dCMe), 135.0 (Cq, i-C Ph), 130.9, 128.6,
and 127.6 (1:2:2, CH each, Ph), 112.9 (dCH2), 104.4 (Cq, C2),
94.8 (CH, C4), 67.4 (3-OCH2), 59.5 (2-OCH2), 18.6 (dCCH3),
15.9 and 14.1 (2 CH2CH3); MS (70 eV, m/ e (%)) 271 (60) [M+],
242 (100), 227 (20), 214 (30), 198 (20), 186 (60).
3
6.25 (1 H, d, J ) 15.5 Hz, dCHPh), 7.20 and 6.90 (2:3 H, m
each, dCHC6H5), 6.53 (1 H, d, 3J ) 15.5 Hz, HCdCHPh), 5.48
(1 H, s, 4-H), 4.15 and 3.40 (1:3 H, 2 diastereotopic OCH2),
1.20 (3 H, t, 3-OCH2CH3), 1.05 (3 H, t, 2-OCH2CH3).
P en ta ca r bon yl[2,3-d ieth oxy-2-(2-p r op en yl)-5-p h en yl-
2H-p yr r ole-N]tu n gsten (12d ) a n d 2,3-Dieth oxy-2-(2-p r o-
p en yl)-5-p h en yl-2H-p yr r ole (13d ). 2,6-Diethoxy-4-phenyl-
1,1,1,1,1-pentacarbonyl-5-aza-1-tungsta-1,3,5,7-nonatetra-
ene (9e; 297 mg, 0.50 mmol) in 2 mL of toluene is heated to
90 °C for 5.5 h. Reaction progress is followed by TLC.
Chromatography on silica gel with pentane/diethyl ether
affords the pale yellow compound 12d (261 mg, 88%, Rf 0.2 in
pentane/diethyl ether (10:1), yellow crystals from pentane at
-15 °C, mp 110 °C). Thermolysis of compound 9e at 110°C
for 6 h affords the metal-free pyrrole 13d together with
W(CO)6.
Ack n ow led gm en t . This investigation was sup-
ported by the Volkswagen-Stiftung and the Fonds der
Chemischen Industrie. Experimental assistance by
Barbara Hildmann is gratefully acknowledged.
Su p p or tin g In for m a tion Ava ila ble: Tables of crystal
data and structure refinement details, positional and displace-
ment parameters, bond distances and angles, and hydrogen
coordinates for 9b, 10b, 11e, and 12b (24 pages). Ordering
information is given on any current masthead page.
12d : 1H NMR (C6D6) δ 7.23 (5 H, m, Ph), 6.10 and 5.30 (1 H
each, s each, dCH2), 4.80 (1 H, s, 4-H), 3.40 and 3.05 (1 H
each, diastereotopic 2-OCH2), 3.25 (2 H, q, 3-OCH2), 1.60 (3
H, s, dCCH3), 1.30 (3 H, t, 3-OCH2CH3), 0.95 (3 H, t,
2-OCH2CH3); 13C NMR (C6D6): δ 201.9 and 199.0 [trans- and
OM9611057