Insertion of alkynes into diterpenoid chromium aminocarbenes: Synthesis of ring-C aromatic steroidal analogues

Article abstract of DOI:10.1016/S0022-328X(01)00736-7

The insertion of alkyl- or aryl-substituted alkynes into chromium aminocarbenes derived from podocarpic acid gives good to excellent yields of cyclopentaannulated products. The presence of a heteroatom bonded directly to the alkyne lowers the yield of the indanones. Although no steroidal derivatives could be isolated from the use of acetylene or its synthons, the electron-deficient alkyne ethyl 4,4-dimethylpentyn-2-oate gave a good yield, as did ethynylferrocene. Novel diterpenoid ferrocenyl quinones were synthesised by reacting diterpenoid chromium alkoxycarbenes with ethynylferrocene.

Full text of DOI:10.1016/S0022-328X(01)00736-7

Journal of Organometallic Chemistry 627 (2001) 206–220
www.elsevier.nl/locate/jorganchem
Insertion of alkynes into diterpenoid chromium aminocarbenes:
synthesis of ring-C aromatic steroidal analogues
Paul D. Woodgate *, Hamish S. Sutherland, Clifton E.F. Rickard
Department of Chemistry, The Uni6ersity of Auckland, Pri6ate Bag 92019, Auckland, New Zealand
Received 21 January 2001; received in revised form 15 February 2001
Abstract
The insertion of alkyl- or aryl-substituted alkynes into chromium aminocarbenes derived from podocarpic acid gives good to
excellent yields of cyclopentaannulated products. The presence of a heteroatom bonded directly to the alkyne lowers the yield of
the indanones. Although no steroidal derivatives could be isolated from the use of acetylene or its synthons, the electron-deficient
alkyne ethyl 4,4-dimethylpentyn-2-oate gave a good yield, as did ethynylferrocene. Novel diterpenoid ferrocenyl quinones were
synthesised by reacting diterpenoid chromium alkoxycarbenes with ethynylferrocene. © 2001 Elsevier Science B.V. All rights
reserved.
Keywords: Chromium; Aminocarbene; Diterpenoid; Alkyne; Cyclopentaannulation; Steroidal
1
. Introduction
able, since further functionalisation of the steroidal
A-ring could then be achieved using the exo methylene
group as a chemical handle. Steroidal natural products
possessing a 4(18)-alkene, albeit without an aromatic
ring C, have been isolated [13–15] from natural
sources, and one has shown anti-inflammatory proper-
ties in rats [16].
Steroids containing an aromatic ring C are relatively
rare, although some have been isolated from sediments
and petroleum [1]. Several have displayed fungistatic
activity, while others, differing in structure only slightly
from that of the cyclopentanoperhydrophenanthrene
steroids, are potentially a source of anti-fertility agents
[
2]. Viridin [3,4], which possesses an aromatic C-ring, is
a steroidal anti-fungal metabolite of the fungus Giocla-
dium 6irens. Our previous experiences in the transfor-
mation of derivatives of podocarpic acid into ring-C
aromatic steroidal analogues [5–11] provided the im-
petus to investigate a route using diterpenoid chromium
aminocarbenes.
2
. Results and discussion
Heteroatom-stabilised chromium carbene complexes
possessing a p system adjacent to the carbene carbon
atom are of particular synthetic value, since they allow
for novel types of cyclisation reactions in which the
chromium moiety acts as a template for annulation of
the carbene ligand. There are relatively few examples of
the formation of five-membered rings from the reaction
of alkynes with aminocarbenes [17–20], since the high
thermal stability of the latter often results in either low
We have recently reported the synthesis of six podo-
carpane chromium aminocarbenes 1–6, possessing an
exocyclic 4(18)-alkene [12]; prior oxidative decarboxyla-
tion of podocarpic acid to give this alkene was desir-
*
Corresponding author. Tel.: +64-9-3737599 ext. 8262; fax: +64-
9
-3737422.
E-mail address: p.woodgate@auckland.ac.nz (P.D. Woodgate).
0
022-328X/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(01)00736-7

P.D. Woodgate et al. / Journal of Organometallic Chemistry 627 (2001) 206–220
207
yields of the carbene annulation products or in uncon-
trolled loss of the transition metal [21]. The reactions
are generally performed by heating the alkyne and the
chromium aminocarbene in refluxing dimethylfor-
mamide (DMF) under nitrogen. The use of DMF as
solvent generally affords high yields of cyclopentaannu-
lation products [22,23], and the formation of side prod-
ucts is minimised compared with the use of either
benzene or THF as solvent [23]. Interestingly, the
product distribution has also been found to be depen-
dent on the nature of the a,b-unsaturated substituent
on the carbene; insertion of alkynes into
at 6.76 and 6.78 ppm, and by resonances due to C(17)
13
at 204.3 and 204.6 ppm in the C-NMR spectrum. The
incorporation of a pentyl chain was confirmed by the
presence of signals due to a methyl group at 14.0 ppm
and methylene groups at 24.4, 27.1 (one epimer), 27.6
(one epimer), 31.8 and 34.3 ppm. The molecular for-
+
’
,
mula was confirmed by the mass spectrum (M
366.2551, C H O ), and expulsion of methyl, ethyl,
25
34
2
butyl and pentyl radicals was observed from the molec-
ular ion.
The data in Table 1 show that increasing methylation
on the nitrogen increases the yield of the steroidal
analogue. Furthermore, the morpholino-substituted
carbene 6 gives the highest yield of the desired product.
The previous argument [25] that increasing the steric
bulk of the amino group shields the chromium from
reactions leading to decomposition is reasonable con-
sidering the set of dihydroamino- (1), methylamino- (2),
dimethylamino- (3) and morpholino- (6) substituted
carbenes. However, the aziridinyl- (4) and pyrrolidinyl-
(5) substituted carbenes gave results which did not fit
this pattern. For insertion of either an alkyne or an
alkene [25], 13-methoxypodocarpane chromium pyrro-
lidinocarbenes give less than satisfactory yields in com-
parison with those reported for simpler systems [22]. It
is therefore suspected that there is some structural or
electronic factor that decreases the stability of either the
ortho-methoxyaryl pyrrolidinocarbenes or of intermedi-
ates arising from them during the insertion sequence.
The lack of insertion products from the reaction of the
aziridinylcarbene 4 with hept-1-yne was unexpected,
since the analogous 19-methoxy complex gave reason-
able yields from the insertion of an alkene [25]. The
morpholinocarbene 6 gave the highest yield of the
indanone 7, and was therefore used in all subsequent
reactions with other alkynes.
(
furyl)aminocarbenes gives a mixture of benzannula-
tion, cyclopentaannulation and bisfuran products [24],
while (aryl)aminocarbenes give only cyclopentaannu-
lated products.
In the present work, we sought initially to establish
that cyclopentaannulation would in fact occur using
tricyclic podocarpane chromium aminocarbenes, and
then to study the variation in the yield of the tetracyclic
product with respect to the substituent(s) on the nitro-
gen atom. Thus, the thermolysis of each of the
aminocarbenes 1–6 with hept-1-yne in refluxing DMF
gave 12-methoxy-4-methylene-15z-pentyl-18-nor-5a-an-
drosta-8,11,13-trien-17-one (7) (Table 1). It was ob-
served empirically that reactions during which the
solution stayed clear and pale orange resulted in high
yields of insertion–cyclisation products, while those
which turned a cloudy brown or orange-brown gave
only low yields. In all cases, both C(15) epimers of 7
were formed in equal amounts, as shown by the pres-
1
ence in the H-NMR spectrum of signals due to H(11)
Table 1
Yield of steroidal analogue 7 vs amino substituent(s)
Thus, reaction of 6 with 3,3-dimethylbutyne gave
1
2-methoxy-4-methylene-15z-(1,1-dimethylethyl)-18-
nor-5a-androsta-8,11,13-trien-17-one (8) (53%) as a
1:1) mixture of epimers. Reaction of 6 with propyne in
(
a sealed pressure bottle (300 kPa, 125°C) gave 12-
methoxy-4-methylene-15z-methyl-18-nor-5a-androsta-
8
,11,13-trien-17-one (9) (50%), also as a (1:1) mixture of
epimers. Doublets of doublets at 2.29 and 2.32 ppm in
1
the H-NMR spectrum of 9 were assigned to one of the
H(16) hydrogens in each epimer, but the signals due to

2
08
P.D. Woodgate et al. / Journal of Organometallic Chemistry 627 (2001) 206–220
the other H(16) proton were obscured by those due to
H(7ax) and H(7eq). Doublets of quartets at 3.35 and
8,11,13,15-tetraene (13) (66%). The location of the dou-
ble bond was determined by 1D- and 2D-NMR experi-
13
1
3.40 ppm were characteristic of H(15). The C-NMR
ments. The singlet at 4.05 ppm in the H-NMR
spectrum showed signals at 31.9 and 31.9(5) ppm as-
signed to C(15) and a signal at 47.4 ppm assigned to
C(16).
spectrum was assigned to H(17), and a COSY spectrum
showed no coupling of this signal with the protons of
either ethyl group. Broad signals at 2.70 (NCH ) and
2
We sought to investigate further the variation in the
yield of the cyclopentaannulated product by changing
the carbene substituent from morpholino to trans-2,6-
dimethylmorpholino, which has been used successfully
in aminocarbene chemistry [26]. Reaction of 3,3-
dimethylbutyne with the trans-2,6-dimethylmorpholi-
nocarbene (10) [12] gave 12-methoxy-4-methylene-
3.64 ppm (OCH ), together with resonances at 49.8
2
13
(NCH ) and 68.3 ppm (OCH ) in the C-NMR spec-
2
2
trum confirmed the presence of the morpholino group,
and a signal at 69.4 ppm in the latter spectrum was
assigned to C(17). The allylamine 13 was relatively
unstable, undergoing a 1,3-hydrogen shift followed by
enamine hydrolysis to give 12-methoxy-4-methylene-
15z,16z-diethyl-18-nor-5a-androsta-8,11,13-trien-17-one
(14). The indanone derivative 14 showed strong absorp-
tion due to a carbonyl group in the infrared spectrum
15z-(1,1-dimethylethyl)-18-nor-5a-androsta-8,11,13-
trien-17-one (8) (20%) as a (1:1) mixture of epimers.
Reaction of 10 with either hept-1-yne or propyne gave
the 15z-pentyl and 15z-methyl androstane analogues, 7
−
1
13
at 1702 cm , and signals in the C-NMR spectrum at
207.3 and 207.4 ppm were assigned to C(17). Overlap
of the signals due to H(15) and H(16) with others in the
(17%) and 9 (14%), respectively, each as a (1:1) mixture
of epimers. Reaction of 3,3-dimethylbutyne with the
analogous 19-methyl ether carbene 11 gave 12-
methoxy-4b-methoxymethyl-4a,15z-dimethyl-18-nor-5a-
androstan-8,11,13-trien-17-one (12) (8%) as a (1:1) mix-
ture of epimers which could be separated by chro-
matography. That is, lower yields of the indanone
derivative were obtained using the sterically more en-
cumbered 2,6-dimethylmorpholino carbene. Since the
morpholinocarbene 6 also gives superior yields com-
pared with aminocarbenes 1–5 possessing less bulky
groups, there is apparently an optimum size for the
nitrogen substituent(s).
1
H-NMR spectrum precluded analysis of the stereo-
chemistry at C(15) and C(16).
Reaction of diphenylethyne with the morpholinocar-
bene 6 gave 12-methoxy-15z,16-diphenyl-4-methylene-
17-morpholino-18-nor-5a-androsta-8,11,13,16-tetraene
(15) in excellent yield (85%). An absorption at 1654
−
1
cm
in the infrared spectrum indicated an enamine
double bond, and a broad singlet at 4.51 ppm in the
1
H-NMR spectrum, consistent with the chemical shift
expected for a hydrogen bound to a doubly benzylic
carbon, was assigned to H(15). Therefore, the enamine
1
5 was formed, rather than an allylamine.
Interestingly, both enamine and allylamine deriva-
tives have been isolated from the reaction of
diphenylethyne with a morpholinocarbene [22]. The
formation of an allylamine or an indanone (via an
enamine) is dependent on whether the cyclopenta-
annulated intermediate undergoes either a 1,3- or a
1,5-hydride shift. Initial decarbonylation of the pen-
tacarbonyl(aminocarbene) leads to a coordinatively un-
saturated tetracarbonyl complex [27,28]. Insertion of
the alkyne into the CrꢀCcarbene bond (Scheme 1) then
Dialkyl alkynes have been reported to give good
yields of insertion products, an allylamine derivative
being favoured when a morpholinocarbene is used
while pyrrolidinocarbenes give the derived indanone
[
22]. Similar results were observed in the present work.
3
Thermolysis of the morpholinocarbene 6 with hex-3-
yne gave the allylamine derivative 12-methoxy-15,16-di-
ethyl-4-methylene-17z-morpholino-18-nor-5a-androsta-
gives the coordinatively saturated h -arylallylidene in-
termediate 16 [29,30], ring closure of which without CO
insertion gives the chromacyclohexadiene 17. Reductive

P.D. Woodgate et al. / Journal of Organometallic Chemistry 627 (2001) 206–220
209
Scheme 1.
elimination affords the cyclopentaannulated intermedi-
ate 18, which can undergo either a 1,3- or a 1,5-hydro-
gen shift to give either an allylamine 19 or an enamine
tions of stannylalkynes with chromium alkoxycarbenes
[33].
20, respectively [18,20,31]. If the alkyne is unsymmetri-
cal, the smaller alkyne substituent (R ) is orientated
S
over the carbene carbon. Therefore, in the present work
the larger substituent (R ) is expected to be directed to
L
C(15) in the steroidal derivative.
In principle, the attachment of a heteroatom to ring
D could be achieved using a heteroatom-substituted
alkyne. Initial studies focussed on alkynes having elec-
tron-rich heteroatom substituents, thermolysis of either
Steroidal derivatives of most relevance biologically
would generally not be substituted at either C(15) or
C(16), and their synthesis using the present methodol-
ogy would require insertion of either acetylene or a
synthon of acetylene. However, thermolysis of the mor-
pholinocarbene 6 with ethyne or trimethylsilylethyne or
tributylstannylethyne gave intractable black tars; no
insertion products were isolated.
(
2-phenyl)trimethylsilylethyne or 1-methylthio-2-phenyl-
ethyne with the morpholinocarbene 6 giving 12-meth-
oxy-16z-phenyl-4-methylene-17-morpholino-18-nor-5a-
androsta-8,11,13,15-tetraene (21) in low yield. Neither
the trimethylsilyl nor the methylthio group was re-
tained, their reductive cleavage presumably involving a
chromium hydride species. The enamine intermediates,
2
2 or 23, underwent facile hydrolysis. Strong absorp-
Previous work has shown that the yield from an
insertion reaction of an aminocarbene with an alkyne
bearing an electron-deficient substituent [22,30] is de-
pendent strongly on the choice of the alkyne [22]. In the
event, heating ethyl 4,4-dimethylpentyn-2-oate with the
carbene 6 gave 15z-(1,1-dimethylethyl)-12-methoxy-4-
methylene - 16z - (carboxyethyl) - 18 - nor - 5a - androsta-
−
1
tion at 1707 cm
confirmed the presence of the C(17) ketone, as did
signals at 203.8 and 204.1 ppm in the C-NMR spec-
trum. As expected, insertion of (2-phenyl)trimethyl-
silylethyne into the aminocarbene proceeded with the
in the infrared spectrum of 21
1
3
larger group (Me Si) over the carbonylchromium moi-
3
8
,11,13-trien-17-one (27) in good yield (54%).
ety, leading to the tetracycle 21 with the phenyl group
at C(16) (Scheme 1). Since a phenyl group is larger than
a methylthio group, the product from 1-methylthio-2-
phenylethyne was expected to be indanone 24, having
the phenyl group at C(15), rather than its 16-phenyl
regioisomer 21. This regiochemistry suggests that the
methylthio group can stabilise the intermediate
methylthio(enamino)carbene 25 electronically [32,33], in
preference to the phenyl(enamino)carbene 26, which
would be produced if the insertion sequence was under
steric control. Similar control of regiochemistry by het-
eroatoms has also been observed in the insertion reac-
The infrared spectrum showed strong absorptions
due to carbonyl groups at 1734 (CꢁOester) and 1709
−
1
13
cm
(CꢁOketone). Signals in the C-NMR spectrum at
168.8 and 168.9 ppm were assigned to the ester car-

2
10
P.D. Woodgate et al. / Journal of Organometallic Chemistry 627 (2001) 206–220
bonyl carbon while those at 196.3 and 196.5 ppm were
68.6 ppm which was assigned to the unsubstituted
cyclopentadienyl ring of the ferrocene substituent.
1
3
assigned to C(17). Although the C-NMR spectrum
showed at most two signals for each carbon, suggesting
that only two steroidal derivatives had formed, the
1
H-NMR spectrum indicated that at least three were
present. Singlets at 3.51 and 3.56 ppm were assigned to
H(15) of two trans isomers, while a doublet at 3.81 ppm
(
J=2.9 Hz) was assigned to H(15) of the cis isomer(s).
The integration sum of these three signals was equal to
that of the two-line signal at 3.72 ppm, which was
assigned to the overlapping signals due to H(16) in all
three stereoisomers. One of the trans isomers (15b-t-Bu,
The benzannulation reaction of ethynylferrocene
with two diterpenoid chromium alkoxycarbenes was
also investigated, since molecules bearing both donor
and acceptor sites are of current interest due to their
electron-transfer properties and as potential candidates
for non-linear optical materials [36–38]. Ferrocene
serves as a good electron donor as well as having a
reversible electrochemical redox couple. 1,4-Benzo-
quinones are good electron acceptors, the redox poten-
tials being tunable by varying the electronic properties
of substituents. Combining these two structural units
therefore provides molecules with potentially useful
electrochemical and optical properties [39].
1
6a-CO Et) crystallised from CDCl –hexanes. X-ray
2
3
diffraction analysis (Fig. 1) located the t-butyl (larger)
group at C(15) and the ester (smaller) group at C(16),
regiochemistry which is consistent with the t-butyl
group being positioned over chromium during coordi-
nation-insertion of the alkyne, thereby minimising unfa-
vourable interactions between it and the diterpenoid
residue.
The isolation also of 13-formyl-12-methoxy-19-nor-
podocarpa-4(18),8,11,13-tetraene (28) from this reac-
tion is thought to reflect oxidative demetallation of the
carbene 6 followed by reduction of the morpholino
carboxamide by a chromium hydride species, leading to
the aldehyde.
There is considerable medicinal and biochemical in-
terest in steroidal derivatives bearing organometallic
substituents, particularly in the treatment of hormone-
dependent cancers [34]. Reaction of ethynylferrocene
[
35] with the morpholinocarbene 6 gave 12-methoxy-4-
methylene-15z-ferrocenyl-18-nor-5a-androsta-8,11,13-
trien-17-one (29) (50%) as a mixture (1:1) of epimers.
The molecular ion was observed at m/z 480.1751
Therefore, ethynylferrocene and pentacarbonyl-
[(methoxy)(13 - (12,19 - dimethoxypodocarpa - 8,11,13-
triene))carbene]chromium (30) were refluxed in THF
for 25 h. The crude 1,4-diphenol product was oxidised
with lead dioxide to give [6aR-(1a,4a,6ab,7a,10aa)]-3-
ferrocenyl - 1,4,5,6,6a,7,8,9,10,10a - decahydro - 12-
methoxy-7-methoxymethyl-7,10a-dimethylchrysene-1,4-
dione (31) (57%). Singlets at 6.85 and 7.25 ppm in the
(
C H FeO ) and was the only significant peak in the
30 32 4
−
1
mass spectrum. An intense peak at 1704 cm
in the
infrared spectrum confirmed the presence of the ketone
1
3
at C(17). The C-NMR spectrum included a signal at
1
H-NMR spectrum were assigned to the quinone hy-
drogen H(2) and to H(11), respectively. Signals due to
the two quinone carbonyls were observed at 185.5 and
13
1
88.0 ppm in the C-NMR spectrum, and a resonance
at 70.2 ppm was assigned to the carbons of the unsub-
stituted cyclopentadienyl ring. Similarly, pentacar-
bonyl[(methoxy)(13 - (19 - norpodocarpa - 4(18),8,11,13-
tetraene)
carbene]chromium
(32)
gave
[6aR-
(
1
1a,4a,6ab,7a,10aa)] - 3 - ferrocenyl - 1,4,5,6,6a,7,8,9,10,
0a-decahydro-12-methoxy-7-methylene-10a-methyl-
chrysene-1,4-dione (33) (57%). Both of the ferrocenyl
diterpenoid 1,4-quinones 31 and 33 were deep green in
−
1
colour. Cyclic voltammetry (0.1 mol l
solution of
Fig. 1. The atomic arrangement in 27.
Bu NCl in MeCN, Pt disc as working electrode,
4

P.D. Woodgate et al. / Journal of Organometallic Chemistry 627 (2001) 206–220
211
Table 2
2.1. X-ray crystal structure of 27
Crystal data and structure refinement parameters for 27
Data were collected on a Siemens SMART area
detector diffractometer using 0.3° frames and profile
fitting. Lorentz, polarisation and absorption corrections
Empirical formula
Formula weight
Temperature (K)
C27H36O4
424.56
203(2)
Wavelength (A
,
)
0.71073
[
41] were applied and equivalent reflections averaged to
Crystal system
Space group
orthorhombic
P2 2 2
give 4305 unique data. Unit cell parameters were ob-
tained by least-squares fit to all data with I\10|(I).
The structure was solved by direct methods [42] and
1
1 1
Unit cell dimensions
a (A
,
)
)
)
16.0838(3)
17.5313(3)
8.6826(2)
2448.23(8)
4
2
b (A
,
refined by full-matrix least-squares on F [43]. Hydro-
c (A
,
V (A )
,
gen atoms were placed geometrically and refined with a
riding model, including free rotation for methyl groups,
with thermal parameter 20% (50% for methyl groups)
greater than Uiso of the carrier atom. All non-hydrogen
atoms were refined with anisotropic thermal parame-
ters. Refinement converged to R1 (observed data)
.0520. Crystal data and refinement parameters are
given in Table 2 and the structure, including the abso-
lute configuration, is shown in Fig. 1.
3
Z
Dcalc. (g cm−3)
1.152
0.076
Absorption coefficient
−
1
(
mm
F(000)
Crystal size (mm)
q Range (°)
)
920
0.88×0.78×0.06
1.72–25.00
20457
0
2
Reflections collected
Observed data
3298
Independent reflections
Max/min transmission
Refinement method
R1 (observed data)
4305 [Rint=0.0385]
0.9955, 0.9364
Full-matrix least-squares on F
2
.2. Summary
2
2
0.0520, wR =0.1227
2
We have shown that ring-C aromatic derivatives of
wR2 (all data)
R =0.0737, wR =0.1357
1
Goodness-of-fit on F2
5a androstan-17-one are accessible in high yield from
the thermally promoted cyclopentaannulation reaction
of podocarpane chromium morpholinocarbenes with
alkyl- or aryl-substituted alkynes, ethyl 4,4-dimethyl-
pentyn-2-oate, or ethynylferrocene. The analogous
chromium methoxycarbenes reacted with ethynylfer-
rocene to give novel ferrocenylquinones.
1.060
calc.
Weighting scheme
2
2
o
2
w=1/[| (F )+(0.0615P) +0.5456P]
where P=(F +2F )/3
2
o
2
c
Absolute structure
parameter
0.9(17)
Largest difference peak
0.24 and −0.189
−
3
and hole (e A
,
)
3
. Experimental
Pt wire as auxiliary electrode, ferrocene as internal
standard) indicated that they are electron-rich, having
oxidation potentials of +0.107 and +0.104 V, respec-
tively.
Since it is possible to tune redox properties by vary-
ing the quinone, and since the use of thiocarbenes in
synthesis is largely unexplored, it was of interest to
investigate the potential preparation of a 1,4-hydroxy-
thiol rather than that of a hydroquinone. Thus, treat-
ment of the chromium methoxycarbene 30 with
Structures were assigned using HRMS (ZB5 ppm)
for the molecular formula, in combination with com-
1
13
plete assignment of the H- and C-NMR spectra and
selected infrared data.
3
.1. Ethyl 4,4-dimethylpentynoate
−1
Butyllithium (4.85 ml, 2.5 mol l , 12.1 mmol) was
added to a stirred solution of 3,3-dimethylbutyne (1.00
g, 12.2 mmol) in THF (10 ml) at −78°C. After 5 min,
this solution was added dropwise to a solution of ethyl
chloroformate (2.32 ml, 24.4 mmol) in THF (2 ml) at
ethanethiol in the presence of Na CO gave penta-
2
3
carbonyl[(ethylthio)(13 - (12,19 - dimethoxypodocarpa-
8,11,13-triene))carbene]chromium (34) (74%). The thio-
−
23°C. The mixture was warmed to room temperature
carbene 34 was then heated under reflux in THF with
ethynylferrocene, acetic anhydride, triethylamine, and
(
r.t.), poured onto saturated aqueous ammonium chlo-
ride, and then extracted with diethyl ether (3×30 ml).
The organic extracts were combined and the solvent
was removed in vacuo. Kugelrohr distillation (5 mmHg,
85°C) gave ethyl 4,4-dimethylpentynoate (1.292 g, 69%)
BF ·OEt [40] for 19 h. Although treatment with lead
3
2
dioxide was not attempted due to the complexity (TLC)
of the crude mixture and the uncertain stability of the
monothioquinone or other products towards oxidation,
the ferrocenylquinone 31 was isolated in very low yield
−
1
as a colourless liquid. IR (cm ): wmax 1711 (CꢁO),
1
1275, 1225. H-NMR (l ppm): 1.29 (s, C(CH ) ); 1.31
3
3
(
3%). Further investigations using thiocarbenes were
(t, [J=6.9 Hz], CH CH ); 4.10–4.27 (m, OCH CH ).
2 3 2 3
13
not undertaken.
C-NMR (l ppm): 13.9 (OCH CH ); 29.8 (C(CH ) );
2
3
3 3

2
12
P.D. Woodgate et al. / Journal of Organometallic Chemistry 627 (2001) 206–220
3
6
0.6 (C(CH ) ); 61.6 (OCH CH ); 63.6 (CꢂCCO Et);
12-OMe); 4.63 (d, [J=1.4 Hz], H(18)); 4.65 (d, [J=1.3
Hz], H(18)); 4.89 (d, [J=1.4 Hz], H(18)); 4.90 (d,
3
3
2
3
2
7.5 (CꢂCCO Et).
2
[
J=1.4 Hz], H(18)); 6.76 (s, H(11)); 6.78 (s, H(11)).
1
3
3.2. 1-Methylthio-2-phenylethyne
C-NMR (l ppm): 14.0 (CH CH CH ); 20.7 (C(6));
2 2 3
2
1.0 (C(6)); 22.5 (C(20)); 22.6 (C(20)); 23.5 (C(2)); 23.6
−
1
Butyllithium (15.8 ml, 1.16 mol l , 18.3 mmol) was
(C(2)); 24.4 (CH CH CH ); 26.1 (C(7)); 27.1 (CH CH -
2
2
3
2
2
added to a solution of phenylethyne (2.0 ml, 18.2
mmol) in THF (40 ml) at −78°C, and dimethyl
disulfide (1.8 ml, 20.0 mmol) was added to the yellow-
brown solution. The mixture was warmed to r.t., water
CH ); 27.6 (CH CH CH ); 31.8 (CH CH CH CH );
3 2 2 3 2 2 2 3
34.3 (BuCH ); 36.0 (C(3)); 36.1 (C(3)); 37.4 (C(15));
2
38.6 (C(1)); 40.6 (C(10)); 40.8 (C(10)); 44.3 (C(16)); 44.9
(C(16)); 46.9 (C(5)); 47.8 (C(5)); 55.5 (12-OMe); 106.6
(C(11)); 106.8 (C(11)); 106.9 (C(18)); 107.1 (C(18));
122.4 (C(8)); 122.8 (C(8)); 124.1 (C(13)); 124.4 (C(13));
149.8 (C(4)); 155.5 (C(12)); 155.6 (C(12)); 156.5 (C(9));
156.7 (C(9)); 160.2 (C(14)); 160.3 (C(14)); 204.3 (C(17));
(
50 ml) was added, and the product was extracted with
ether (150 ml). The organic extract was dried (MgSO4)
and the solvent was removed in vacuo. Column chro-
matography (hexanes) followed by Kugelrohr distilla-
tion (1.5 mmHg, 65°C) gave 1-methylthio-2-
phenylethyne (2.092 g, 78%) as a pale yellow liquid. IR
+
204.6 (C(14)). m/z: 366 (M , 100), 351 (M−Me, 7),
’
337 (M−Et, 26); 321 (8), 309 (M−Bu , 9); 295 (M−
−
1
’
(
7
cm ): wmax 2927 (CHalkyl), 2168 (CꢂC), 1595 (CꢁC),
C H , 15).
5
11
1
54 (CHo.o.p.), 690 (CHo.o.p.). H-NMR (l ppm): 2.45 (s,
SCH ); 7.24–7.31 (m, Hpara, Hmeta); 7.38–7.43 (m,
3
3
.4. Reaction of pentacarbonyl[(methylamino)-
1
3
Hortho).
C-NMR (l ppm): 19.3 (SCH3); 80.8
(
13-(12-methoxy-19-norpodocarpa-4(18),8,11,13-
(
1
CꢂCSMe); 91.7 (CꢂCSMe); 123.3 (Cipso); 127.9 (Cpara);
tetraene))carbene]chromium (2) with hept-1-yne
28.1 (Cmeta); 131.3 (Cortho).
A solution of pentacarbonyl[(methylamino)(13-(12-
methoxy - 19 - norpodocarpa - 4(18),8,11,13 - tetraene))-
carbene]chromium (2) (0.236 g, 0.496 mmol) in DMF
3
.3. Reaction of pentacarbonyl[(dihydro)-
(
13-(12-methoxy-19-norpodocarpa-4(18),8,11,13-
tetraene))carbene]chromium (1) with hept-1-yne
(
10 ml) was purged with nitrogen. Hept-1-yne was
added and the solution was then heated to 120°C for 3
h. Usual workup followed by radial chromatography
A solution of pentacarbonyl[(dihydroamino)(13-(12-
methoxy - 19 - norpodocarpa - 4(18),8,11,13 - tetraene))-
carbene]chromium (1) (0.230 g, 0.499 mmol) in DMF
(
hexanes–ether, 1:1) gave 12-methoxy-4-methylene-18-
nor-15z-pentyl-5a-androsta-8,11,13-trien-17-one (7)
39.2 mg, 22%).
(
10 ml) was purged with nitrogen. Hept-1-yne (0.15 ml,
(
1
1
.1 mmol) was added and the solution was heated to
20°C for 3 h. The mixture was cooled, diluted with
3
(
.5. Reaction of pentacarbonyl[(dimethylamino)-
13-(12-methoxy-19-norpodocarpa-4(18),8,11,13-
tetraene))carbene]chromium (3) with hept-1-yne
ether (3×20 ml), and the organic layer was washed
with water and dried (MgSO ). PLC (hexanes–ether,
4
2
1
:1; two elutions) gave 12-methoxy-4-methylene-18-nor-
5z-pentyl-5a-androsta-8,11,13-trien-17-one (7) (31.3
+
’
A solution of pentacarbonyl[(dimethylamino)(13-(12-
methoxy - 19 - norpodocarpa - 4(18),8,11,13 - tetraene))-
carbene]chromium (3) (0.171 g, 0.349 mmol) in DMF (7
ml) was purged with nitrogen. Hept-1-yne (0.10 ml,
mg, 17%) as a colourless oil. Found: 366.2551 [M ].
Calc. for C H O : 366.2559 [M ]. IR (cm ): wmax
+
’
−1
2
5
34
2
1
703 (CꢁO), 1597 (CꢁC), 1582 (CꢁC), 1051 (CꢀOꢀC).
1
H-NMR (l ppm): 0.87 (t, [J=6.7 Hz], CH CH CH );
2
2
3
0
1
.76 mmol) was added and the solution was heated to
20°C for 3 h. Usual workup followed by radial chro-
0
.88 (t, [J=6.7 Hz], CH CH CH ); 1.04 (s, H(20)); 1.08
2 2 3
(
s, H(20)); 1.20–1.35 (bm, CH CH CH CH CH ); 1.58
2 2 2 2 3
matography (hexanes–ether, 2:1) gave 12-methoxy-4-
methylene-18-nor-15z-pentyl-5a-androsta-8,11,13-trien-
(
1
ddd, [J=13.0, 13.0, 4.6 Hz], H(1ax)); 1.62 (ddd, [J=
3.0, 13.0, 4.6 Hz], H(1ax)); 1.65–1.90 (m, H(2ax),
1
7-one (7) (64.9 mg, 51%).
H(2eq), H(6ax), BuCH ); 1.95 (bdd, [J=13.1, 6.4 Hz],
2
H(6eq)); 2.06 (ddd, [J=13.2, 13.2, 5.5 Hz], H(3ax));
2
[
(
.09 (ddd, [J=13.2, 13.2, 5.5 Hz], H(3ax)); 2.20 (bd,
J=12.4 Hz], H(5)); 2.26 (bd, [J=12.4 Hz], H(5)); 2.28
bd, [J=12.3 Hz], H(1eq)); 2.40 (bd, [J=13.1 Hz],
H(3eq)); 2.41 (d, [J=3.6 Hz], H(16) (one isomer)); 2.46
d, [J=3.6 Hz], H(16) (one isomer)); 2.65–2.82 (m,
H(7ax), H(16) (both isomers)); 2.88 (ddd, [J=16.5, 5.8,
3.6. Reaction of pentacarbonyl[(aziridinyl)-
(13-(12-methoxy-19-norpodocarpa-4(18),8,11,13-
tetraene))carbene]chromium (4) with hept-1-yne
(
A
solution of pentacarbonyl[(aziridinyl)(13-(12-
methoxy-19-norpodocarpa-4(18),8,11,13-tetraene))car-
bene]chromium (4) (0.268 g, 0.55 mmol) in DMF (10
ml) was purged with nitrogen. Hept-1-yne (84 ml, 0.64
mmol) was added, and the solution was heated to
1
3
.6 Hz], H(7eq)); 2.98 (bdd, [J=17.1, 5.0 Hz], H(7eq));
.20 (3 lines, [J=8.9, 7.1 Hz], H(15)); 3.29 (3 lines,
[
J=8.7, 7.7 Hz], H(15)); 3.91 (s, 12-OMe); 3.92 (s,

P.D. Woodgate et al. / Journal of Organometallic Chemistry 627 (2001) 206–220
213
1
20°C for 3 h. Usual workup gave an oil which was a
H(2eq)); 1.78 (qt, [J=13.4, 4.1 Hz], H(2ax)); 1.80–1.95
(m, H(6ax), H(6eq)); 2.07 (ddd, [J=13.4, 13.4, 5.5 Hz],
H(3ax)); 2.10 (ddd, [J=13.3, 13.3, 5.3 Hz], H(3ax));
2.20–2.25 (m, H(5)); 2.26 (bd, [J=11.9 Hz], H(1eq));
mixture of at least 20 compounds (TLC; hexanes–
ether, 1:1), all bands being of approximately equal
intensity (UV).
2
.31 (bd, [J=11.9 Hz], H(1eq)); 2.40, bd, [J=13.0 Hz],
3
.7. Reaction of pentacarbonyl[(pyrrolidinyl)-
H(3eq)); 2.55 (ddd, [J=17.0, 11.4, 7.4 Hz], H(7ax) (one
isomer)); 2.63 (6 lines, H(16ax), H(16eq)); 2.81–2.96
(m, H(7ax) (one isomer), H(7eq)); 3.20 (dd, [J=5.4, 2.1
Hz], H(15)); 3.26 (dd, [J=5.6, 1.9 Hz], H(15)); 3.90 (s,
12-OMe); 3.91 (s, 12-OMe); 4.62 (d, [J=0.9 Hz],
H(18)); 4.65 (d, [J=0.9 Hz], H(18)); 4.88 (s, H(18));
(
13-(12-methoxy-19-norpodocarpa-4(18),8,11,13-
tetraene))carbene]chromium (5) with hept-1-yne
A solution of pentacarbonyl[(pyrrolidinyl)(13-(12-
methoxy - 19 - norpodocarpa - 4(18),8,11,13 - tetraene))-
carbene]chromium (5) (0.214 g, 0.415 mmol) in DMF
1
3
4.90 (s, H(18)); 6.78 (s, H(11)); 6.83 (s, H(11)). C-
NMR (l ppm): 20.8 (C(6)); 21.2 (C(6)); 22.6 (C(20));
23.3 (C(20)); 23.4 (C(2)); 23.6 (C(2)); 26.4 (C(7)); 28.1
(C(CH ) ); 28.2 (C(7)); 28.4 (C(CH ) ); 35.8 (C(3)); 36.0
(
10 ml) was purged with nitrogen. Hept-1-yne (0.15 ml,
1
1
.1 mmol) was added and the mixture was heated to
20°C for 3 h. Extraction with ether (3×25 ml) fol-
3
3
3 3
lowed by workup and radial chromatography (hex-
(C(3)); 36.9 (C(CH ) ); 37.6 (C(CH ) ); 38.2 (C(1));
3 3 3 3
anes–ether, 2:1) gave 12-methoxy-4-methylene-18-nor-
38.9(5) (C(1)); 40.9 (C(10)); 41.0 (C(10)); 45.0 (C(16));
45.2 (C(16)); 47.1 (C(15)); 47.2 (C(5)); 47.8 (C(15)); 48.4
(C(5)); 55.5(0) (12-OMe); 55.5(5) (12-OMe); 106.8
15z-pentyl-5a-androsta-8,11,13-trien-17-one (7) (11 mg,
7%).
(
C(18)); 106.9(5) (C(11)); 107.0 (C(18)); 107.7 (C(11));
3
.8. Reaction of pentacarbonyl[(morpholino)-
123.4 (C(8)); 123.9 (C(8)); 125.5 (C(13)); 126.3 (C(13));
147.9 (C(4)); 149.9 (C(4)); 154.9(9) (C(12)); 155.0(4)
(
13-(12-methoxy-19-norpodocarpa-4(18),8,11,13-
tetraene))carbene]chromium (6) with 1-hept-1-yne
(C(12)); 155.9 (C(9)); 157.9 (C(14)); 158.2 (C(14)); 203.9
+
(
C(17)); 204.1 (C(17)). m/z: 352 (M , 30), 296 (M−
’
(CH ) CꢁCH , 100), 295 (M−(CH ) C , 19), 281
+
A solution of pentacarbonyl[(morpholino)(13-(12-
methoxy - 19 - norpodocarpa - 4(18),8,11,13 - tetraene))-
carbene]chromium (6) (0.280 g, 0.527 mmol) in DMF
3
2
2
3 3
’
(296−Me , 26), 57 ((CH ) C , 23).
3
3
Repeating this reaction but omitting the photolytic
decomplexation step gave 15z-(1,1-dimethylethyl)-12-
methoxy-4-methylene-18-nor-5a-androsta-8,11,13-trien-
17-one (8) (53%).
(
10 ml) was purged with nitrogen. Hept-1-yne (1.14
mmol) was added and the mixture was heated to 120°C
for 3 h. Usual workup and radial chromatography
(
hexanes–ether, 1:1) gave 12-methoxy-4-methylene-18-
nor-15z-pentyl-5a-androsta-8,11,13-trien-17-one (7)
145 mg, 75%).
3.10. Reaction of pentacarbonyl[(morpholino)-
(13-(12-methoxy-19-norpodocarpa-4(18),8,11,13-
tetraene))carbene]chromium (6) with propyne
(
3.9. Reaction of pentacarbonyl[(morpholino)-
(
13-(12-methoxy-19-norpodocarpa-4(18),8,11,13-
A solution of pentacarbonyl[(morpholino)(13-(12-
methoxy - 19 - norpodocarpa - 4(18),8,11,13 - tetraene))-
carbene]chromium (6) (0.256 g, 0.443 mmol) in DMF
(10 ml) in a pressure bottle was purged with nitrogen
and then pressurised with propyne and heated to 120°C
for 1 h. Usual workup followed by PLC (hexanes–
ether, 1:1) gave 12-methoxy-15z-methyl-4-methylene-
18-nor-5a-androsta-8,11,13-trien-17-one (9) (69 mg,
tetraene))carbene]chromium (6) with 3,3-dimethylbutyne
A solution of pentacarbonyl[(morpholino)(13-(12-
methoxy - 19 - norpodocarpa - 4(18),8,11,13 - tetraene))-
carbene]chromium (6) (0.301 g, 0.566 mmol) in DMF
(
(
heated to 120°C for 3.5 h. The cooled solution was
diluted with ether (40 ml) and water (20 ml), and then
photolysed for 24 h under a fluorescent lamp. The
organic layer was washed with water (2×20 ml) and
dried. PLC (hexanes–ether, 1:1) gave 15z-(1,1-
dimethylethyl)-12-methoxy -4-methylene-18-nor-5a-
androsta-8,11,13-trien-17-one (8) (0.1054 g, 53%).
10 ml) was purged with nitrogen. 3,3-Dimethylbutyne
0.30 ml, 2.4 mmol) was added and the mixture was
+
’
50%) as a white foam. Found: 310.1934 [M ]. Calc.
+
’
−1
for C H O : 310.1933 [M ]. IR (cm ): wmax 1704
21
26
2
1
(CꢁO), 1598 (CꢁC), 1582 (CꢁC), 1045 (CꢀOꢀC). H-
NMR (l ppm): 1.04 (s, H(20)); 1.09 (s, H(20)); 1.28 (d,
[J=7.0 Hz], 15-CH ); 1.32 (d, [J=6.9 Hz], 15-CH );
3
3
1.58 (ddd, [J=12.9, 12.9, 4.7 Hz], H(1ax)); 1.65–1.90
(m, H(2ax), H(2eq), H(6ax)); 1.95 (dd, [J=13.0, 6.2
Hz], H(6eq)); 2.06 (ddd, [J=13.0, 13.0, 5.4 Hz],
H(3ax)); 2.09 (ddd, [J=13.3, 13.3, 5.6 Hz], H(3ax));
2.21 (5 lines, H(5)); 2.28 (bd, [J=10.5 Hz], H(1eq));
2.29 (dd, [J=2.9, 1.1 Hz], H(16) (one isomer)); 2.33
(dd, [J=2.9,1.1 Hz], H(16) (one isomer)); 2.40 (bd,
[J=12.1 Hz], H(3eq)); 2.68–2.95 (m, H(7ax), H(7eq)
+
’
Found: 352.2400 [M ]. Calc. for C H O : 352.2402
24
32
2
+
’
]. IR (cm ): wmax 1708 (CꢁO), 1592 (CꢁC), 1580
1
−1
[
M
(
CꢁC), 1049 (CꢀOꢀC). H-NMR (l ppm): 0.88 (s,
C(CH ) ); 0.89 (s, C(CH ) ); 1.03 (s, H(20)); 1.08 (s,
3
3
3 3
H(20)); 1.59 (ddd, [J=12.0, 12.0, 6.1 Hz], H(1ax)); 1.60
ddd, [J=12.0, 12.0, 6.1 Hz], H(1ax)); 1.62–1.70 (m,
(

2
14
P.D. Woodgate et al. / Journal of Organometallic Chemistry 627 (2001) 206–220
(
5
one isomer), H(16) (both isomers)); 3.02 (dd, [J=17.2,
.2 Hz], H(7eq) (one isomer)); 3.35 (dq, [J=7.0, 6.8
Hz], H(15)); 3.40 (dq, [J=7.0, 6.8 Hz], H(15)); 3.63(2)
s, 12-OMe); 3.63(6) (s, 12-OMe); 4.64 (d, [J=1.4 Hz],
H(18)); 4.65 (d, [J=1.2 Hz], H(18)); 4.89(6) (s, H(18));
pholino)(13-(12-methoxy-19-norpodocarpa-4(18),8,11,
13-tetraene)carbene]chromium (10) (50.2 mg, 0.0897
mmol) in DMF (2 ml) was purged with nitrogen in a
pressure bottle, which was then charged with propyne
(
(
300 kPa). The solution was heated to 125°C for 3 h.
Usual workup followed by PLC (hexanes–ether, 1:1)
gave
4
.90 (s, H(18)); 6.76(5) (s, H(11)); 6.78 (s, H(11)).
C-NMR (l ppm): 20.6 (C(6)); 20.8 (C(20)); 21.0
C(6)); 22.1 (C(20)); 22.5 (15-CH ); 22.7 (15-CH ); 23.5
1
3
12-methoxy-15z-methyl-4-methylene-18-nor-5a-
(
(
(
(
(
(
(
(
(
3
3
androsta-8,11,13-trien-17-one (9) (3.8 mg, 14%) as a
C(2)); 23.6 (C(2)); 26.1 (C(7)); 31.9 (C(15)); 31.9(5)
C(15)); 36.0 (C(3)); 36.1 (C(3)); 38.6 (C(1)); 40.6
C(10)); 40.8 (C(10)); 47.4 (C(16)); 47.8 (C(5)); 55.5
12-OMe); 106.7 (C(11)); 106.8(9) (C(11)); 106.9(3)
C(18)); 107.1 (C(18)); 121.9 (C(8)); 122.3 (C(8)); 124.1
C(13)); 124.5 (C(13)); 149.8 (C(4)); 155.7 (C(12)); 156.5
C(9)); 156.8 (C(9)); 161.2 (C(14)); 161.3 (C(14)); 204.1
mixture (1:1) of epimers.
3.14. Reaction of pentacarbonyl[(trans-2,6-dimethyl-
morpholino)(13-(12,19-dimethoxypodocarpa-8,11,13
-
triene)carbene]chromium (11) with 3,3-dimethylbutyne
+
C(17)); 204.4 (C(17)). m/z: 310 (M , 100), 295 (M−
’
’
Me , 13), 281 (M−CO−H ), 265 (20); 253 (44).
A solution of pentacarbonyl[(trans-2,6-dimethylmor-
pholino)(13-(12-methoxy-19-norpodocarpa-4(18),8,11,
3-tetraene)carbene]chromium (11) (52.4 mg, 0.0865
mmol) in DMF (1 ml) was purged with nitrogen.
,3-Dimethylbutyne (22 ml, 0.179 mmol) was added and
the solution was heated to 125°C for 3 h. Usual workup
followed by PLC (hexanes–ether, 1:1) gave: (i) 12-
methoxy-4b-methoxymethyl-4a,15-dimethyl-18-nor-5a-
androstan-8,11,13-trien-17-one (12) (less polar epimer)
3
.11. Reaction of pentacarbonyl[(trans-2,6-dimethyl-
morpholino)(13-(12-methoxy-19-norpodocarpa-
(18),8,11,13-tetraene)carbene]chromium (10) with
1
4
3
hept-1-yne
A solution of pentacarbonyl[(trans-2,6-dimethylmor-
pholino)(13-(12-methoxy-19-norpodocarpa-4(18),8,11,
13-tetraene)carbene]chromium (10) (75.8 mg, 0.136
+
’
1.4 mg, 4%). Found: 398.2820 [M ]. Calc. for
(
mmol) in DMF (3 ml) was purged with nitrogen.
Hept-1-yne (36 ml, 0.274 mmol) was added and the
solution was heated to 125°C for 3 h. Usual workup
followed by PLC (hexanes–ether, 1:1) gave 12-
methoxy-4-methylene-15z-pentyl-18-nor-5a-androsta-
+
’
−1
C H O : 398.2821 [M ]. IR (cm ): wmax 1708
26 38
3
1
(
CꢁO). H-NMR (l ppm): 1.06 (ddd, [J=13.1, 13.1,
.1 Hz], H(3ax)); 1.08 (s, H(18)); 1.22 (s, H(20)); 1.30 (s,
C(CH ); 1.45 (dd, [J=12.3, 2.0 Hz], H(5)); 1.48–1.70
4
)
3 3
8
,11,13-trien-17-one (7) (8.5 mg, 17%) as a mixture (1:1)
(m, H(1ax), H(2eq), H(6ax)); 1.78 (qt, [J=13.4, 2.9
Hz], H(2ax)); 1.87 (bd, [J=13.3 Hz], H(3eq)); 2.03
of epimers.
(
bdd, [J=13.1, 6.8 Hz], H(6eq)); 2.28 (bd, [J=12.7
3
.12. Reaction of pentacarbonyl[(trans-2,6-dimethyl-
Hz], H(6eq)); 2.61 (5 lines, H(16ax), H(16eq)); 2.75–
2.93 (m, H(7ax), H(7eq)); 3.18 (dd, [J=5.7, 1.8 Hz],
H(15)); 3.29 (d, [J=9.2 Hz], H(19)); 3.33 (s, 19-OMe);
morpholino)(13-(12-methoxy-19-norpodocarpa-
4
3
(18),8,11,13-tetraene)carbene]chromium (10) with
,3-dimethylbutyne
3
.50 (d, [J=9.2 Hz], H(19)); 3.90 (s, 12-OMe); 6.76 (s,
+
H(11)). m/z: 398 (M , 34), 342 (M−(CH ) CꢁCH ,
1
methoxymethyl-4a,15-dimethyl-18-nor-5a-androstan-
8
4
3
3
2
2
A solution of pentacarbonyl[(trans-2,6-dimethylmor-
+
3
00), 57 (C(CH ) , 43) and (ii) 12-methoxy-4b-
3
pholino)(13-(12-methoxy-19-norpodocarpa-4(18),8,11,
3-tetraene)carbene]chromium (10) (71.2 mg, 0.127
mmol) in DMF (3 ml) was purged with nitrogen.
,3-Dimethylbutyne (32 ml, 0.26 mmol) was added and
1
,11,13-trien-17-one (12) (more polar epimer) (1.2 mg,
+
’
%). Found: 398.2818 [M ]. Calc. for C H O :
26
38
3
3
+
−1
1
’
98.2821 [M ]. IR (cm ): wmax 1708 (CꢁO). H-NMR
the solution was heated to 125°C for 3 h. Usual workup
followed by PLC (hexanes–ether, 1:1) gave 15z-(1,1-
dimethylethyl)-12-methoxy -4-methylene-18-nor-5a-
androsta-8,11,13-trien-17-one (8) (8.8 mg, 20%) as a
(
1
l ppm): 1.00 (ddd, [J=13.1, 13.1, 4.1 Hz], H(3ax));
.03 (s, H(18)); 1.25 (bs, H(20), C(CH ) ); 1.39 (dd,
3
3
[J=12.6, 3.3 Hz], H(5)); 1.50–1.85 (m, H(1ax), H(2ax),
H(2eq), H(6ax)); 1.89 (bd, [J=13.8 Hz], H(3eq)); 1.98–
(
1:1) mixture of epimers.
2
2
2
3
.03 (m, H(6eq)); 2.30 (bd, [J=12.7 Hz], H(1eq));
.55–2.65 (m, H(7ax), H(16)); 3.17 (ddd, [J=17.1, 7.0,
.8 Hz], H(7eq)); 3.20 (bdd, [J=5.8, 1.5 Hz], H(15));
.32 (d, [J=9.2 Hz], H(19)); 3.35 (s, 19-OMe); 3.55 (d,
3
.13. Reaction of pentacarbonyl[(trans-2,6-dimethyl-
morpholino)(13-(12-methoxy-19-norpodocarpa-
(18),8,11,13-tetraene)carbene]chromium (10) with
propyne
4
[
J=9.1 Hz], H(19)); 3.92 (s, 12-OMe); 6.77 (s, H(11)).
+
m/z: 398 (M , 32), 342 (M−(CH ) CꢁCH , 100), 57
(C(CH ) , 17).
3 3
3
2
2
+
A solution of pentacarbonyl[(trans-2,6-dimethylmor-

P.D. Woodgate et al. / Journal of Organometallic Chemistry 627 (2001) 206–220
215
3
.15. Reaction of pentacarbonyl[(morpholino)-
H(18)); 4.90 (bs, H(18)); 6.75 (s, H(11)); 6.76 (s, H(11)).
13
(
13-(12-methoxy-19-norpodocarpa-4(18),8,11,13-
C-NMR (l ppm): 11.4 (CH CH ); 12.0(5) (CH CH );
2 3 2 3
tetraene))carbene]chromium (6) with hex-3-yne
12.1 (CH CH ); 12.2 (CH CH ); 20.7 (C(6)); 20.9
2 3 2 3
(
C(6)); 22.6 (C(20)); 23.5 (C(2)); 23.6 (C(2)); 24.4
A solution of pentacarbonyl[(morpholino)(13-(12-
methoxy-19-norpodocarpa-4(18),8,11,13-tetraene))car-
bene]chromium (6) (0.308 g, 0.580 mmol) in DMF (10
ml) was purged with nitrogen, followed by the addition
of hex-3-yne (0.15 ml, 1.3 mmol). The solution was
heated to 120°C for 3 h. Usual workup followed by
radial chromatography gave 15,16-diethyl-12-methoxy-
(CH CH ); 26.0 (CH CH ); 26.5 (C(7)); 26.6(6) (C(7));
2
3
2
3
26.7 (CH CH ); 28.4 (CH CH ); 36.0 (C(3)); 36.1
2
3
2
3
(C(3)); 38.4 (C(1)); 38.6 (C(1)); 40.6 (C(10)); 40.8
(C(10)); 45.0 (C(5)); 46.8 (C(16)); 47.8 (C(16)); 55.4
(12-OMe); 56.0 (C(15)); 56.9 (C(15)); 106.5 (C(11));
106.8 (C(11)); 106.9 (C(18)); 107.0 (C(18)); 121.7 (C(8));
122.2 (C(8)); 124.3 (C(13)); 124.6 (C(13)); 149.9 (C(4));
155.6 (C(12)); 155.7 (C(12)); 156.4 (C(9)); 156.7 (C(9));
158.9 (C(14)); 159.2 (C(14)); 207.3 (C(17)); 207.4
4
8
4
- methylene - 17z - morpholino - 18 - nor - 5a - androsta-
,11,13,15-tetraene (13) (0.162 g, 66%). Found:
+
’
+
’
+
’
(C(17)). m/z: 352 (M , 83), 337 (M−Me , 9), 324
21.2987 [M ]. Calc. for C H O N: 421.2981 [M ].
28
39
2
−
1
1
’
’
IR (cm ): wmax 1587 (CꢁC), 1116. H-NMR (l ppm):
(M−CO, 100), 295 (324−Me , 33), 267 (324−Et ,
1.07 (t, [J=7.5 Hz], CH CH ); 1.08 (s, H(20)); 1.09 (t,
19), 309 (18).
2
3
[
J=7.5 Hz], CH CH ); 1.16 (t, [J=7.5 Hz], CH CH );
2 3 2 3
1
.58 (m, H(1ax)); 1.67–1.95 (m, H(2ax), H(2eq),
3.16. Reaction of pentacarbonyl[(morpholino)(13-(12-
methoxy-19-norpodocarpa-4(18),8,11,13-tetraene))-
carbene]chromium (6) with diphenylethyne
H(6ax), H(6eq)); 2.01–2.12 (m, H(3ax)); 2.20 (bd, [J=
1
2
2.6 Hz], H(5)); 2.28 (bd, [J=13.4 Hz], H(1eq)); 2.33–
.46 (m, H(3eq), CH CH ); 2.63 (q, [J=7.5 Hz],
2
3
CH CH ); 2.70 (b, NCH ); 3.00 (ddd, [J=16.4, 12.2,
A solution of pentacarbonyl[(morpholino)(13-(12-
methoxy-19-norpodocarpa-4(18),8,11,13-tetraene))car-
bene]chromium (6) (0.252 g, 0.474 mmol) and
diphenylethyne (0.126 g, 0.707 mmol) in DMF (10 ml)
was purged with nitrogen then heated to 120°C for 3 h.
Usual workup followed by radial chromatography gave
12 - methoxy - 4 - methylene - 17z - morpholino - 15,16-
2
3
2
5
3
.6 Hz], H(7ax)); 3.25 (bdd, [J=16.3, 4.2 Hz], H(7eq));
.64 (b, OCH ); 3.83 (s, 12-OMe); 4.02 (s, H(17)); 4.05
2
(
6
s, H(17)); 4.61 (s, H(18)); 4.86 (d, [J=1.2 Hz], H(18));
1
3
.68 (s, H(11)). C-NMR (l ppm): 14.5 (CH CH );
2 3
1
4.7 (CH CH ); 15.6 (CH CH ); 19.2 (CH CH ); 20.4
2
3
3
2
3
2
(
(
C(6)); 20.6 (C(6)); 21.4 (C(20)); 22.8 (C(20)); 22.9
C(2)); 23.8 (C(2)); 26.4 (C(7)); 26.5 (C(7)); 36.2 (C(3));
diphenyl-18-nor-5a-androsta-8,11,13,16-tetraene
(15)
+
’
39.5 (C(1)); 40.2 (C(10)); 40.3 (C(10)); 47.2 (C(5)); 47.4
(0.2092 g, 85%). Found: 517.2986 [M ]. Calc. for
+
’
C H NO : 517.2981 [M ]. IR (cm ): wmax 1645
36 39 2
−1
(
(
(
C(5)); 49.8 (NCH ); 54.7 (12-OMe); 68.3 (OCH ); 69.3
C(17)); 69.4 (C(17)); 104.9 (C(18)); 105.0 (C(18)); 106.3
C(11)); 121.3 (C(8)); 127.7(5) (C(13)); 127.9 (C(13));
2
2
1
(CꢁN), 1601 (CꢁC), 737 (CHo.o.p.), 701 (CHo.o.p.). H-
NMR (l ppm): 1.00 (s, H(20)); 1.03 (s, H(20)); 1.52
(ddd, [J=13.0, 13.0, 4.6 Hz], H(1ax)); 1.53 (ddd, [J=
13.0, 13.0, 4.6 Hz], H(1ax)); 1.58–1.98 (m, H(2ax),
H(2eq), H(6ax), H(6eq)); 2.03 (ddd, [J=13.6, 13.6, 4.9
Hz], H(3ax)); 2.05 (bd, [J=12.5 Hz], H(5)); 2.13 (bd,
[J=12.5 Hz], H(5)); 2.25–2.37 (m, H(3eq)); 2.50 (ddd,
[J=17.2, 11.9, 7.3 Hz], H(7ax)); 2.64 (bdd, [J=17.3,
1
1
1
3
39.4 (C(16)); 139.6 (C(16)); 144.9 (C(15)); 147.1 (C(4));
47.5 (C(4)); 148.9 (C(14)); 149.0 (C(14)); 150.7 (C(9));
+
’
53.4 (C(12)). m/z: 421 (M , 10), 406 (M−Me , 5),
’
92 (M−Et , 29), 334 (M−C H NO, 100).
4
9
The allylamine (13) hydrolysed to 15z,16z-diethyl-12-
methoxy-4-methylene-18-nor-5a-androsta-8,11,13-trien-
+
’
1
7-one (14). Found: 352.2398 [M ]. Calc. for
3.9 Hz], H(7eq)); 2.86–2.90 (m, NCH ); 3.02 (bt, [J=
2
+
’
−1
C H O : 352.2402 [M ]. IR (cm ): wmax 1702
11.7 Hz], NCH ); 3.72 (dd, [J=8.6, 4.2 Hz], OCH );
2
4
32
2
2
2
1
(
0
CꢁO), 1598 (CꢁC), 1581 (CꢁC). H-NMR (l ppm):
.87 (t, [J=7.4 Hz], CH CH ); 0.93 (t, [J=7.4 Hz],
3.92 (s, 12-OMe); 3.94 (s, 12-OMe); 4.51 (bs, H(18),
H(15)); 4.61 (s, H(18)); 4.78 (s, H(18)); 4.80 (s, H(18));
6.88–6.94 (m, H(11), Ph (3H)); 6.98 (dd, [J=7.8, 1.9
2
3
CH CH ); 1.00 (t, [J=7.4 Hz], CH CH ); 1.02 (t, [J=
2
3
2
3
13
7
.4 Hz], CH CH ); 1.05 (s, H(20)); 1.08 (s, H(20)); 1.36
Hz], Hortho); 7.05–7.16 (m, Ph, 6H). C-NMR (l ppm):
20.8 (C(6)); 20.9 (C(6)); 22.7 (C(20)); 22.9 (C(20)); 23.7
(C(2)); 23.8 (C(2)); 26.9(5) (C(7)); 36.1 (C(3)); 36.3
(C(3)); 38.8 (C(1)); 38.9 (C(1)); 39.7 (C(10)); 39.8
2
3
(
bq, [J=7.4 Hz], CH CH ); 1.39 (qd, [J=7.4, 1.9 Hz],
2 3
CH CH ); 1.42 (qd, [J=7.3, 1.9 Hz], CH CH ); 1.64
2
3
2
3
(
ddd, [J=12.6, 12.6, 4.4 Hz], H(1ax)); 1.70–1.96 (m,
H(2ax), H(2eq), H(6ax), H(6eq)); 2.06 (ddd, [J=12.7,
2.7, 5.1 Hz], H(3ax)); 2.09 (ddd, [J=12.7, 12.7, 5.5
Hz], H(3ax)); 2.22 (bd, [J=12.0 Hz], H(5)); 2.25–2.31
m, H(1eq), H(16)); 2.40 (bd, [J=12.8 Hz], H(3eq));
(C(10)); 47.0 (C(5)); 47.4 (C(5)); 52.2 (NCH ); 55.7(5)
2
1
(12-OMe); 55.8 (12-OMe); 57.6(5) (C(15)); 57.7 (C(15));
67.5 (OCH ); 106.4 (C(18)); 106.6 (C(18)); 108.1
2
(
(C(11)); 108.2 (C(11)); 124.1(8) (C(8)); 124.2(4) (C(8));
126.0 (C(13)); 126.1(5) (C(13)); 126.4 (CHaromatic);
127.1(5) (CHaromatic(2H)); 128.0 (CHaromatic); 128.1
(CHaromatic); 128.4 (CHaromatic(2H)); 128.5 (Cquat); 128.8
(Cquat); 130.1(7) (CHaromatic); 130.2 (CHaromatic); 133.1
2.65–2.92 (m, H(15), H(7ax), H(7eq) (one isomer));
2.97 (ddd, [J=17.0, 6.2, 1.0 Hz], H(7eq) (one isomer));
3.90(7) (s, 12-OMe); 3.91 (s, 12-OMe); 4.64 (d, [J=1.4
Hz], H(18)); 4.65 (d, [J=1.4 Hz], H(18)); 4.89(5) (bs,

2
16
P.D. Woodgate et al. / Journal of Organometallic Chemistry 627 (2001) 206–220
(
1
(
1
Cquat); 133.6 (Cquat); 137.4 (CHaromatic); 139.0 (C(16));
39.5 (C(16)); 146.2(5) (C(17)); 146.2(5) (C(17)); 146.6
C(4)); 146.9 (C(4)); 147.1 (C(14)); 147.2 (C(14));
50.3(7) (C(9)); 150.4(1) (C(9)); 151.0 (C(12)); 151.1
methoxy-19-norpodocarpa-4(18),8,11,13-tetraene))car-
bene]chromium (6) (0.214 g, 0.402 mmol) in DMF (8
ml) was purged with nitrogen and 1-methylthio-2-
phenylethyne (0.122 g, 823 mmol) was added. The
solution was heated to 120°C for 3 h. Usual workup
followed by PLC (hexanes–ether, 1:1 then 7:3) gave
12-methoxy-4-methylene-16z-phenyl-18-nor-5a-an-
drosta-8,11,13-trien-17-one (21) (5.1 mg, 3%).
+
(
C(12)). m/z: 517 (M , 100), 431 (M−C H NO, 14).
4
8
3
(
.17. Reaction of pentacarbonyl[(morpholino)-
13-(12-methoxy-19-norpodocarpa-4(18),8,11,13-
tetraene))carbene]chromium (6) with trimethyl-
(
2-phenylethynyl)silane
3
.19. Reaction of pentacarbonyl[(morpholino)(13-(12-
A solution of pentacarbonyl[(morpholino)(13-(12-
methoxy - 19 - norpodocarpa - 4(18),8,11,13 - tetraene))-
carbene]chromium (6) (0.296 g, 0.557 mmol) in DMF
methoxy-19-norpodocarpa-4(18),8,11,13-tetraene))-
carbene]chromium (6) with ethyne
(
10 ml) was purged with nitrogen. Trimethyl(2-
A solution of pentacarbonyl[(morpholino)(13-(12-
methoxy - 19 - norpodocarpa - 4(18),8,11,13 - tetraene))-
carbene]chromium (6) (0.245 g, 0.461 mmol) in DMF
phenylethynyl)silane (0.23 ml, 1.14 mmol) was added
and the solution was heated to 120°C for 3 h. Usual
workup followed by PLC (hexanes–ether, 2:1) gave
(
10 ml) was purged with nitrogen and then with ethyne.
The pressure bottle was then pressurised with ethyne
300 kPa) and heated to 125°C for 1 h, giving a
1
2-methoxy-4-methylene-16z-phenyl-18-nor-5a-an-
+
’
drosta-8,11,13-trien-17-one (21). Found: 372.2080 [M ].
Calc. for C H O : 372.2089 [M ]. IR (cm ): wmax
(
+
’
−1
2
6
28
2
dark-red polymeric material. Usual workup gave a
dark-brown oil which was dissolved in ether and de-
colourised with charcoal. PLC of the residue gave an
unidentified product (1.8 mg).
1
707 (CꢁO), 1599 (CꢁC), 1580 (CꢁC), 1049 (CꢀOꢀC).
1
H-NMR (l ppm): 1.02 (s, H(20)); 1.03 (s, H(20)); 1.51
ddd, [J=13.4, 13.4, 6.0 Hz], H(1ax)); 1.60–2.08 (m,
(
H(2ax), H(2eq), H(3ax), H(3eq), H(6ax), H(6eq)); 2.14
bd, [J=11.9 Hz], H(5)); 2.22–2.40 (m, H(1eq), H(3eq),
H(7ax) (one isomer), H(5) (one isomer)); 2.42 (dd,
J=13.2, 2.5 Hz], H(15)); 2.47–2.55 (m, H(7ax) (one
isomer)); 2.57 (dd, [J=13.3, 2.4 Hz], H(15)); 2.63 (ddd,
J=17.1, 5.8, 1.2 Hz], H(7eq)); 3.16 (dd, [J=11.3, 8.4
Hz], H(15)); 3.21 (dd, [J=11.4, 8.4 Hz], H(15)); 3.97 (s,
2-OMe); 3.98 (s, 12-OMe); 4.41 (d, [J=8.4 Hz],
H(16)); 4.45 (d, [J=8.4 Hz], H(16)); 4.54 (bs, H(18));
.82 (bs, H(18)); 4.84 (bs, H(18)); 6.84 (s, H(11)); 6.87
s, H(11)); 7.04 (bd, [J=7.2 Hz], Hortho); 7.20 (bt,
(
3
.20. Reaction of pentacarbonyl[(morpholino)(13-(12-
[
methoxy-19-norpodocarpa-4(18),8,11,13-tetraene))-
carbene]chromium (6) with trimethylsilylethyne
[
Trimethylsilylethyne (0.28 ml, 1.98 mmol) was added
to a nitrogen-purged solution of pentacarbonyl[(mor-
pholino)(13-(12-methoxy-19-norpodocarpa-4(18),8,11,
1
4
(
1
3-tetraene))-carbene]chromium (6) (0.247 g, 0.499
mmol) in DMF (10 ml), and the mixture was heated at
120°C for 3.25 h. Usual workup gave a brown viscous
oil, which was dissolved in ether and filtered through
charcoal. PLC (hexanes–ether, 2:1) failed to yield any
products. Repeating the reaction in refluxing DMF also
gave intractable tars.
[
J=7.0 Hz], Hpara); 7.24 (dd, [J=7.8, 1.6 Hz], Hmeta).
C-NMR (l ppm): 20.5 (C(6)); 20.6 (C(6)); 22.5
1
3
(
(
C(20)); 22.6 (C(20)); 23.5 (C(2)); 23.6 (C(2)); 26.3
C(7)); 35.9 (C(3)); 36.1 (C(3)); 38.4 (C(1)); 38.6 (C(1));
40.5(6) (C(10)); 40.6(3) (C(10)); 43.5 (C(15)); 43.6
(
(
C(15)); 46.8 (C(5)); 47.1 (C(5)); 48.3 (C(16)); 48.5
C(16)); 55.6 (12-OMe); 106.9 (C(11)); 107.1 (C(11));
1
1
07.2 (C(18)); 107.3 (C(18)); 123.4 (C(8)); 123.5 (C(8));
25.3 (C(13)); 125.4 (C(13)); 126.5 (Cpara); 127.1
3.21. Reaction of pentacarbonyl[(morpholino)(13-(12-
methoxy-19-norpodocarpa-4(18),8,11,13-tetraene))-
carbene]chromium (6) with tributylstannylethyne
(
Cmeta);127.3 (Cmeta);128.8 (Cortho); 128.9 (Cortho); 143.6
Cipso); 144.1 (Cipso); 149.6(9) (C(4)); 149.7(2) (C(4));
(
1
1
55.4 (C(12)); 155.5 (C(12)); 157.1 (C(9)); 157.4 (C(9));
57.9 (C(14)); 158.2 (C(14)); 203.8 (C(17)); 204.1
A solution of pentacarbonyl[(morpholino)(13-(12-
methoxy-19-norpodocarpa-4(18),8,11,13-tetraene))car-
bene]chromium (6) (0.253 g, 0.476 mmol) in DMF (10
ml) was purged with nitrogen. Tributylstannylethyne
(0.28 ml, 0.968 mmol) was added and the mixture was
heated to 120°C for 3 h. Usual workup gave a brown
polymeric oil which was decolourised with charcoal.
PLC (hexanes–ether, 2:1) gave a product (0.2 mg)
which was not characterised.
+
’
(
(
C(17)). m/z: 372 (M , 100), 357 (M−Me , 7), 343
M−CO−H, 37), 315 (18), 253 (12).
3.18. Reaction of pentacarbonyl[(morpholino)(13-(12-
methoxy-19-norpodocarpa-4(18),8,11,13-tetraene))-
carbene]chromium (6) with 1-methylthio-2-phenylethyne
A solution of pentacarbonyl[(morpholino)(13-(12-

P.D. Woodgate et al. / Journal of Organometallic Chemistry 627 (2001) 206–220
217
3.22. Reaction of pentacarbonyl[(morpholino)-
(l ppm): 14.0 (OCH CH ); 20.8 (C(6)); 21.1 (C(6)); 22.4
2 3
(
13-(12-methoxy-19-norpodocarpa-4(18),8,11,13-
(C(20)); 23.4 (C(2)); 23.5 (C(20)); 23.6 (C(2)); 26.3
tetraene))carbene]chromium (6) with ethyl 4,4-
dimethylpentyn-2-oate
(C(7)); 28.1(5) (C(CH ) ); 28.5 (C(CH ) ); 35.8 (C(3));
3
3
3 3
36.0 (C(3)); 36.4 (C(CH ) ); 37.2 (C(CH ) ); 38.0 (C(1));
3
3
3 3
3
9.0 (C(1)); 40.9(5) (C(10)); 41.1 (C(10)); 46.9 (C(5));
A solution of pentacarbonyl[(morpholino)(13-(12-
methoxy-19-norpodocarpa-4(18),8,11,13-tetraene))car-
bene]chromium (6) (0.240 g, 0.452 mmol) in DMF (10
ml) was purged with nitrogen. Ethyl 4,4-dimethylpen-
tyn-2-oate (0.149 g, 0.966 mmol) was added and the
mixture was heated to 120°C for 3 h. Usual workup
followed by PLC (hexanes–ether, 1:1) gave: (i) 13-
formyl - 12 - methoxy - 19 - norpodocarpa - 4(18),8,11,13-
tetraene (28) (7 mg, 6%) as colourless needles (m.p.
48.3(5) (C(5)); 51.7 (C(15)); 51.7 (C(15)); 55.5 (12-
OMe); 59.8 (12-OMe); 61.4(7) (OCH CH ); 61.5(2)
2
3
(OCH CH ); 61.9 (C(16)); 106.9(2) (C(18)); 106.9(9)
2
3
(C(18)); 107.0(2) (C(11)); 107.8 (C(11)); 121.9 (C(8));
122.4 (C(8)); 125.7(5) (C(13)); 126.5(5) (C(13)); 149.6
(C(4)); 149.9 (C(4)); 155.5 (C(12)); 155.7 (C(12)); 156.9
(C(9)); 157.3(5) (C(9)); 158.4 (C(14)); 168.8 (COOEt);
168.9 (COOEt); 196.3 (C(17)); 196.5 (C(17)). m/z: 424
+
(M , 66), 368 (M−CH ꢁCMe , 100), 322 (M−
2
2
+
’
’ ’
(CH ) C −EtO , 64), 295 (368−EtO C, 83).
3 3 2
1
53–155°C). Found: 270.1651 [M ]. Calc. for
+
’
−1
C H O : 270.1620 [M ]. IR (cm ): wmax 1676
1
8
22
2
1
(
CꢁO), 1609 (CꢁC). H-NMR (l ppm): 1.04 (s, H(20));
.61 (ddd, [J=12.8, 12.8, 4.5 Hz], H(1ax)); 1.69–1.90
m, H(2ax), H(2eq), H(6ax), H(6eq)); 2.07 (ddd, [J=
2.9, 12.9, 5.5 Hz], H(3ax)); 2.20 (bd, [J=12.7 Hz],
H(5)); 2.27 (bd, [J=12.8 Hz], H(1eq)); 2.40 (ddd, [J=
3.23. Reaction of pentacarbonyl[(morpholino)(13-(12-
methoxy-19-norpodocarpa-4(18),8,11,13-tetraene))-
carbene]chromium (6) with ethynylferrocene
1
(
1
A solution of ethynylferrocene (0.144 g, 0.686 mmol)
1
6
3.1, 4.3, 2.3 Hz], H(3eq)); 2.85 (ddd, [J=16.8, 11.9,
.5 Hz], H(7ax)); 2.91 (ddd, [J=16.8, 6.4, 1.9 Hz],
and
pentacarbonyl[(morpholino)(13-(12-methoxy-19-
norpodocarpa - 4(18),8,11,13 - tetraene)) - carbene]chro-
mium (6) (0.244 g, 0.459 mmol) in DMF (10 ml) was
purged with nitrogen and then heated to 120°C for 3 h.
Usual workup followed by radial chromatography
(hexanes–ether, 2:1) gave 15z-ferrocenyl-12-methoxy-4-
methylene-18-nor-5a-androsta-8,11,13-trien-17-one (29)
(0.109 g, 50%) as an orange foam. Found: 480.1751
H(7eq)); 3.86 (s, 12-OMe); 4.62 (d, [J=1.5 Hz], H(18));
.88 (d, [J=1.5 Hz], H(18)); 6.89 (s, H(11)); 7.55 (s,
4
1
3
H(14)); 10.39 (s, CHO). C-NMR (l ppm): 21.1 (C(6));
2
3
2.5(5) (C(20)); 23.5 (C(2)); 28.8 (C(7)); 36.1 (C(3));
8.2(5) (C(1)); 40.4 (C(10)); 47.3(5) (C(5)); 55.6 (12-
OMe); 107.1 (C(18)); 108.4 (C(11)); 122.8 (C(13)); 127.7
+
’ ’
[M ]. Calc. for C H FeO : 480.1752 [M ]. IR
30 32 4
+
(
(
C(8)); 129.3 (C(14)); 149.7 (C(4)); 156.1 (C(9)); 159.9
C(12)); 189.7 (CHO). m/z: 270 (M , 100), 255 (M−
+
−1
(cm ): wmax 1704 (CꢁO), 1598 (CꢁC), 1581 (CꢁC),
1049 (CꢀOꢀC). H-NMR (l ppm): 1.00 (s, H(20)); 1.02
’
1
Me , 21), 227 (255−CO, 42); and (ii) 16z-(ethylcar-
boxy)-15z-(1,1-dimethylethyl)-12-methoxy-4-methylene-
(s, H(20)); 1.55 (ddd, [J=12.6, 12.6, 4.5 Hz], H(1ax));
1.60–1.85 (m, H(2ax), H(2eq), H(6ax), H(6eq)); 1.99
(ddd, [J=13.5, 13.5, 5.5 Hz], H(3ax)); 2.03 (ddd, [J=
13.5, 13.5, 5.5 Hz], H(3ax)); 2.09 (d, [J=13.2 Hz],
H(5)); 2.13 (d, [J=13.2 Hz], H(5)); 2.19 (bd, [J=12.7
Hz], H(1eq)); 2.26 (bd, [J=12.7 Hz], H(1eq)); 2.36 (bd,
[J=12.9 Hz], H(3eq)); 2.47 (ddd, [J=17.4, 12.5, 6.7
Hz], H(7ax)); 2.57 (bdd, [J=17.4, 7.3 Hz], H(7eq));
2.76 (dd, [J=17.0, 4.5 Hz], H(16)); 2.94 (dd, [J=17.2,
5.9 Hz], H(16)); 3.26 (bd, [J=5.2 Hz], H(15)); 3.72 (bt,
[J=1.1 Hz], H(2%) (one isomer)); 3.77 (bt, [J=1.2 Hz],
H(2%) (one isomer)); 3.91 (s, 12-OMe); 3.93 (s, 12-OMe);
4.08 (b, H(2%)); 4.12 (m, H(3%)); 4.14 (s, Cp); 4.17 (s,
Cp); 4.28 (bt, [J=1.0 Hz], H(3%)); 4.34 (bt, [J=1.2 Hz],
H(3%)); 4.58 (d, [J=1.2 Hz], H(18)); 4.59 (d, [J=1.2
Hz], H(18)); 4.84 (d, [J=1.1 Hz], H(18)); 4.86 (d,
[J=1.1 Hz], H(18)); 6.75 (s, H(11)); 6.80 (s, H(11)).
1
8-nor-5a-androsta-8,11,13-trien-17-one (27) (54%);
trans isomer as colourless crystals (CDCl –hexanes),
m.p. 177–180°C. Found: 424.2614 [M ]. Calc. for
C H O : 424.2607 [M ]. IR (cm ): wmax 1734
3
+
’
+
’
−1
2
7
36
4
(
CꢁOester), 1709 (CꢁOketone), 1596 (CꢁC), 1579 (CꢁC).
H-NMR (l ppm): 0.89 (s, (CH ) C); 0.90 (s, (CH ) C);
1
3
3
3 3
1
.05 (s, H(20)); 1.07 (s, H(20)); 1.11 (s, H(20)); 1.23 (t,
[
J=7.2 Hz], OCH CH ); 1.24 (t, [J=7.2 Hz],
2 3
OCH CH ); 1.60–1.95 (m, H(1ax), H(2ax), H(2eq),
H(6ax), H(6eq)); 2.08 (ddd, [J=12.3, 12.3, 4.6 Hz],
H(3ax)); 2.11 (ddd, [J=12.2, 12.2, 5.1 Hz], H(3ax));
2
3
2
.24–2.33 (m, H(1eq), H(5)); 2.42 (bd, [J=11.5 Hz],
H(3eq)); 2.68 (ddd, [J=17.0, 12.0, 6.7 Hz], H(7ax));
2
1
H(15)trans); 3.72 (2 lines, H(16)); 3.81 (d, [J=2.9 Hz],
H(15) ); 3.90 (s, 12-OMe); 3.91 (s, 12-OMe); 4.07 (dd,
.90–2.97 (5 lines, H(7ax), H(7eq)); 3.29 (ddd, [J=
7.0, 5.1, 2.1 Hz], H(7eq)); 3.51 (s, H(15)trans); 3.56 (s,
13
C-NMR (l ppm): 20.5 (C(6)); 20.7 (C(6)); 22.4
cis
[
7
J=13.2, 7.2 Hz], OCH CH ); 4.07(5) (dd, [J=13.2,
(C(20)); 22.6 (C(20)); 23.4 (C(2)); 23.5 (C(2)); 24.5
(C(7)); 26.6 (C(7)); 35.8(5) (C(3)); 36.1 (C(3)); 36.5
(C(16)); 36.8 (C(16)); 38.4 (C(1)); 38.6 (C(1)); 40.5
(C(10)); 40.6 (C(10)); 46.6 (C(5)); 47.2 (C(5)); 49.0
(C(15)); 49.7 (C(15)); 55.5 (12-OMe); 55.6 (12-OMe);
65.8 (C(2%)); 66.3 (C(2%)); 66.5 (C(2%)); 66.6 (C(2%)); 67.5
2
3
.2 Hz], OCH CH ); 4.10 (dd, [J=13.2, 7.2 Hz],
2 3
OCH CH ); 4.11 (dd, [J=13.2, 7.2 Hz], OCH CH );
4
H(18)); 4.88(5) (d, [J=1.5 Hz], H(18)); 4.89 (d, [J=1.1
Hz], H(18)); 6.79 (s, H(11)); 6.83 (s, H(11)). C-NMR
2
3
2
3
.62 (d, [J=1.2 Hz], H(18)); 4.65 (d, [J=1.1 Hz],
13

2
18
P.D. Woodgate et al. / Journal of Organometallic Chemistry 627 (2001) 206–220
(
9
1
(
1
C(3%)); 67.8 (C(3%)); 68.6 (Cp); 69.5 (C(3%)); 70.1 (C(3%));
1.9 (C(1%)); 93.2 (C(1%)); 106.8 (C(18)); 107.0 (C(11));
07.2 (C(11)); 121.7(5) (C(8)); 122.1 (C(8)); 125.1
refluxed for 19 h. The solvent was removed in vacuo
and the residue was dissolved in dichloromethane (20
ml). Lead dioxide (2.54 g, 10.6 mmol) was added and
the mixture was stirred for 30 min at r.t. and then
filtered. Radial chromatography (hexanes–ether, 1:1)
C(13)); 125.2 (C(13)); 149.7 (C(4)); 155.4 (C(14));
56.6(7) (C(9)); 156.7(5) (C(9)); 158.4 (C(12)); 158.9
+
(
1
C(12)); 204.3(7) (C(17)); 204.4 (C(17)). m/z: 480 (M ,
gave
6a,7,8,9,10,10a - decahydro - 12 - methoxy - 7 - methylene-
0a-methylchrysene-1,4-dione (33) (0.154 g, 57%) as a
[6aR-(1a,4a,6ab,7a,10aa)]-3-ferrocenyl-1,4,5,6,
00).
1
+
’
dark-green foam. Found: 506.1550 [M ]. Calc. for
3
1
.24. [6aR-(1h,4h,6hi,7h,10ah)]-3-Ferrocenyl-
,4,5,6,6a,7,8,9,10,10a-decahydro-12-methoxy-7-
+
’
−1
C H FeO : 506.1544 [M ]. IR (cm ): wmax 1704
(CꢁO), 1643, 1601 (CꢁC). H-NMR (l ppm): 1.10 (s,
1
31
30
3
1
methoxymethyl-7-10a-dimethylchrysene-1,4-dione (31)
0a-Me); 1.59 (ddd, [J=12.7, 12.7, 4.8 Hz], H(10ax));
A solution of pentacarbonyl[(methoxy)(13-(12,19-
dimethoxypodocarpa-8,11,13-triene))carbene]chromium
1.66–1.88 (m, H(9ax), H(9eq), H(6ax), H(6eq)); 2.01
(m, H(8ax)); 2.09 (dd, [J=13.1, 5.4 Hz], H(6a)); 2.27
(bd, [J=12.4 Hz], H(10eq)); 2.41 (bd, [J=13.2 Hz],
H(8eq)); 3.20–3.31 (m, H(5ax), H(5eq)); 3.98 (s, 12-
OMe); 4.14 (s, Cp); 4.54 (6 lines, [J=1.4 Hz], H(2%));
4.55 (6 lines, [J=1.4 Hz], H(2%)); 4.66 (d, [J=1.4 Hz],
(
30) (0.314 g, 0.601 mmol) and ethynylferrocene (0.151
g, 0.719 mmol) in THF (15 ml) was refluxed for 25 h.
The solvent was removed in vacuo and the residue was
dissolved in dichloromethane (30 ml). Lead dioxide
(
3.042 g, 12.7 mmol) was added and the mixture was
stirred at r.t. for 1 h and then filtered. Radial chro-
matography (hexanes–ether, 1:1) gave [6aR-
1a,4a,6ab,7a,10aa)] - 3 - ferrocenyl - 1,4,5,6,6a,7,8,9,10,
7-CH ); 4.89 (5 lines, [J=1.3 Hz], H(3%)); 4.91 (d,
2
[J=1.3 Hz], 7-CH ); 4.99 (5 lines, H(3%)); 6.86 (s, H(2));
2
13
7.27 (bs, H(11)). C-NMR (l ppm): 21.2 (C(6)); 22.8
(10a-Me); 23.5 (C(9)); 29.2 (C(9)); 35.8 (C(8)); 38.9
(C(10)); 40.8 (C(10a)); 46.7 (C(6a)); 56.4 (12-OMe); 69.4
(C(3%)); 69.6 (C(3%)); 70.2 (Cp); 71.5 (C(2%)); 71.6 (C(2%));
(
1
0a-decahydro-12-methoxy-7-methoxymethyl-7-10a-
dimethylchrysene-1,4-dione (31) (0.190 g, 57%) as a
dark-green foam. Found: 552.1971 [M ]. Calc. for
C H FeO : 552.1963 [M ]. IR (cm ): wmax 1709
+
’
76.2 (C(1%)); 107.2 (7-CH ); 115.3 (C(2)); 119.9 (C(12a));
2
+
’
−1
129.4 (C(4b)); 131.1 (C(11)); 133.9 (C(4a)); 149.4 (C(7));
3
3
36
4
1
(
CꢁO), 1643, 1601 (CꢁC). H-NMR (l ppm): 1.04 (ddd,
J=13.5, 13.5, 4.1 Hz], H(8ax)); 1.08 (s, 7-Me); 1.28 (s,
0a-Me); 1.47 (dd, [J=12.8, 1.7 Hz], H(6a)); 1.48 (ddd,
J=12.8, 12.8, 4.0 Hz], H(10ax)); 1.60–1.75 (m,
H(9eq), H(6ax)); 1.77 (qt, [J=13.9, 3.6 Hz], H(9ax));
.89 (bd, [J=13.4 Hz], H(8eq)); 2.13 (m, H(6eq)); 2.31
bd, [J=12.7 Hz], H(10eq)); 3.25–3.33 (m, H(5ax),
H(5eq)); 3.28 (d, [J=9.2 Hz], 7-CH OMe); 3.35 (s,
149.8 (C(10a)); 156.0 (C(12)); 157.2 (C(3)); 184.5 (CꢁO);
+
[
1
[
187.8 (CꢁO). m/z: 506 (M , 52), 480 (100), 442 (M−
’
Cp +H, 20). E1 (V) −1.317; 0.104.
/2
3.26. Pentacarbonyl[(ethylthio)(13-(12,19-dimethoxy-
podocarpa-8,11,13-triene))carbene]chromium (34)
1
(
Ethanethiol (50 ml, 0.67 mmol) and sodium carbonate
(0.100 g, 0.943 mmol) were added to a solution of
pentacarbonyl[(methoxy)(13 - (12,19 - dimethoxypodo-
carpa-8,11,13-triene))carbene]chromium (30) (0.295 g,
0.565 mmol) in isopropanol (4 ml) at 0°C. The suspen-
sion was stirred at 0°C for 1 h and then at r.t. for 21 h.
The red-brown solution was extracted with diethyl
ether, and the extracts were washed with water, and
2
7
1
-CH OMe); 3.52 (d, [J=9.2 Hz], 7-CH OMe); 3.98 (s,
2
2
2-OMe); 4.14 (s, Cp); 4.54 (10 lines, H(2%)); 4.89 (5
lines, H(3%)); 4.98 (5 lines, H(3%)); 6.85 (s, H(2)); 7.25 (s,
H(11)). C-NMR (l ppm): 19.2 (C(9)); 19.4 (C(6));
2
3
1
3
5.6 (10a-Me); 27.5 (7-Me); 30.6 (C(5)); 35.7 (C(8));
7.9 (C(10a)); 39.6 (C(7), C(10)); 50.2 (C(6a)); 56.4
(
(
(
12-OMe); 59.4 (7-CH OMe); 69.4(5) (C(3%)); 69.5(5)
2
C(3%)); 70.2 (Cp); 71.4(8) (C(2%)); 71.5(4) (C(2%)); 76.0
7-Me); 76.2 (C(1%)); 114.5(5) (C(2)); 119.7 (C(12a));
29.4 (C(4b)); 131.2 (C(11)); 133.6 (C(4a)); 149.8
dried (MgSO ). Solvent was removed by passing a
4
constant stream of dry nitrogen over the solution in a
well-ventilated fumehood. Radial chromatography
(hexanes–ether; 9:1) gave pentacarbonyl[(thioethyl)(13-
(12,19 - dimethoxypodocarpa - 8,11,13 - triene))carbene]-
chromium (34) (0.232 g, 74%) as a viscous red-black oil,
the ratio of the two rotamers being ca. 1.2:1. Found:
1
(
1
0
C(10a)); 157.3 (C(12)); 158.7(5) (C(3)); 185.5(5) (CꢁO);
+
88.0 (CꢁO). m/z: 552 (M , 100). E (V) −1.330;
1
/2
.107.
+
’
552.1293 [M ]. Calc. for C H CrO S: 552.1274
27 32 7
3
6
1
.25. [6aR-(1h,4h,6hi,7h,10ah)]-3-Ferrocenyl-1,4,5,6,
a,7,8,9,10,10a-decahydro-12-methoxy-7-methylene-
0a-methylchrysene-1,4-dione (33)
+
’
−1
[M ]. IR (cm ): w
2055 (s, CꢂO), 1990 (sh, CꢂO),
max
1
1937 (br, CꢂO). H-NMR (l ppm): 1.01 (m, H(3ax));
.05 (s, H(18)); 1.11 (t, [J=7.7 Hz], SCH CH ); 1.20(7)
1
2
3
A
solution of pentacarbonyl[(methoxy)(13-(12-
(s, H(20)); 1.21 (s, H(20)); 1.22 (s, H(20)); 1.46 (bt,
[J=12.9 Hz], H(1ax)); 1.60–1.80 (m, H(2ax), H(5),
H(2eq), H(6ax)); 1.88 (bd, [J=13.1 Hz], H(3eq)); 1.97
(m, H(6eq)); 2.27 (b, H(1eq)); 2.67–2.90 (m, H(7ax),
methoxy-19-norpodocarpa-4(18),8,11,13-tetraene))car-
bene]chromium (31) (0.252 g, 0.529 mmol) and ethynyl-
ferrocene (0.130 g, 0.619 mmol) in THF (10 ml) was

P.D. Woodgate et al. / Journal of Organometallic Chemistry 627 (2001) 206–220
697.
219
2
H(7eq)); 2.71 (q, [J=7.7 Hz], SCH CH ); 3.25 (d,
[
(
3
2
3
[
2] H.C. Dalzell, A. Manmade, A.R. Mastrocola, R.K. Razdan, J.
Org. Chem. 44 (1979) 2457.
3] J.F. Grove, J.S. Moffatt, E.B. Vischer, J. Chem. Soc. (1965)
J=9.2 Hz], H(19)); 3.27 (d, [J=9.2 Hz], H(19)); 3.33
s, 19-OMe); 3.33(9) (s, 19-OMe); 3.34(1) (s, 19-OMe);
.52 (d, [J=9.2 Hz], H(19)); 3.54 (d, [J=9.2 Hz],
H(19)); 3.74 (s, 12-OMe); 6.14 (s, H(14)); 6.16 (s, H(14));
[
3
803.
[4] J.F. Grove, P. McClosky, J.S. Moffat, J. Chem. Soc. (C) (1966)
43.
1
3
7
6
.76 (s, H(11)). C-NMR (l ppm): 12.0 (SCH CH );
2 3
[
5] R.C. Cambie, P.S. Rutledge, R.J. Stevenson, P.D. Woodgate, J.
Organomet. Chem. 471 (1994) 133.
6] R.C. Cambie, P.S. Rutledge, R.J. Stevenson, P.D. Woodgate, J.
Organomet. Chem. 471 (1994) 149.
1
(
3
3
(
1
(
1
2
(
(
9.2 (C(2)); 19.4 (C(6)); 25.6 (C(20)); 25.7 (C(20)); 27.6
C(18)); 30.2 (C(7)); 30.3 (C(7)); 30.4 (C(7)); 36.0 (C(3));
[
8.0 (C(4), C(10)); 38.7 (SCH CH ); 38.8 (SCH CH );
2 3 2 3
9.1 (C(1)); 51.1 (C(5)); 51.2 (C(5)); 51.3 (C(5)); 55.1
[7] R.C. Cambie, M.R. Metzler, P.S. Rutledge, P.D. Woodgate, J.
Organomet. Chem. 429 (1992) 41.
12-OMe); 59.4 (19-OMe); 75.9 (C(19)); 76.1 (C(19));
06.4 (C(11)); 106.6 (C(11)); 106.9 (C(11)); 118.0(8)
C(14)); 118.1(4) (C(14)); 126.8 (C(13)); 128.7 (C(8));
[
8] R.C. Cambie, M.R. Metzler, C.E.F. Rickard, P.S. Rutledge,
P.D. Woodgate, J. Organomet. Chem. 426 (1992) 213.
9] R.C. Cambie, M.R. Metzler, P.S. Rutledge, P.D. Woodgate, J.
Organomet. Chem. 429 (1992) 59.
[
44.0 (C(9)); 144.1 (C(9)); 150.2 (C(12)); 215.9 (CꢂO );
cis
+
29.0 (CꢂOtrans); 362.4 (Ccarbene). m/z: 552 (M , 4), 524
[10] P.W.R. Harris, P.D. Woodgate, Synth. Commun. 27 (1997)
4195.
11] R.C. Cambie, P.S. Rutledge, M. Tercel, P.D. Woodgate, J.
Organomet. Chem. 315 (1986) 171.
12] P.D. Woodgate, H.S. Sutherland, C.E.F. Rickard, J. Organomet.
Chem. 626 (2001) 199.
M−CO, 9), 496 (M−2CO, 3); 468 (M−3CO, 8); 440
M−4CO, 55), 412 (M−5CO, 52), 384 (43), 377 (33),
[
3
61 (81), 331 (35), 315 (412−Cr−MeOCH , 100).
2
[
3
.27. Reaction of pentacarbonyl[(thioethyl)(13-(12,19-
[13] L. Dolej sˇ , H. Hanu sˇ , Z. Voticky, J. Tomko, Collect. Czech.
Chem. Commun. 30 (1965) 2869.
dimethoxypodocarpa-8,11,13-triene))-carbene]chromium
[
14] K.S. Brown Jr., S.M. Kupchan, J. Am. Chem. Soc. 86 (1964)
424.
(
34) with ethynylferrocene
4
[
[
15] R.H. Burnell, M. Soucy, Phytochemistry 11 (1972) 1853.
16] T. Saidkasimov, Farmakol. Prir. Veschestv (1978) 74 [Chem.
Abstr. 91 (1979) 235j].
17] W.D. Wulff, in: E.W. Abel, F.G.A. Stone, G. Wilkinson (Eds.),
Comprehensive Organometallic Chemistry II, vol. 12, Pergamon
Press, New York, 1995, p. 469.
18] D.B. Grotjahnn, K.H. D o¨ tz, Synlett (1991) 381.
19] M.A. Schwindt, J.R. Miller, L.S. Hegedus, J. Organomet. Chem.
413 (1991) 143.
A solution of pentacarbonyl(ethylthio)(13-(12,19-
dimethoxypodocarpa - 8,11,13 - triene)) - carbene]-
chromium (34) (0.164 g, 0.297 mmol), triethylamine
[
(
0.210 ml, 1.51 mmol), BF ·Et O (0.21 ml, 1.71 mmol)
3 2
and ethynylferrocene (0.129 g, 0.614 mmol) in THF (10
ml) was refluxed for 19 h. The solvent was removed in
vacuo, the residue was dissolved in ether and the solution
[
[
[
[
[
20] A. de Meijere, H. Schirmer, M. Duetsch, Angew. Chem. Int. Ed.
was washed with water and dried (MgSO ). PLC (hex-
4
Engl. 39 (2000) 3964.
21] K.H. D o¨ tz, H.-G. Erben, K. Harms, J. Chem. Soc. Chem.
Commun. (1989) 692.
anes–ether, 9:1) gave ethynylferrocene (75.6 mg, 59%)
and a mixture of products, some fractions of the 24-com-
ponent mixture were combined and re-plated on a
22] A. Yamashita, Tetrahedron Lett. 27 (1986) 5915.
2
2
0×20 cm TLC plate (hexanes–ether, 1:1). Recovery
[23] W.D. Wulff, A.M. Gilbert, R.P. Hsung, A. Rahm, J. Org.
Chem. 60 (1995) 4566.
[
from the most intense deep green band gave [6aR-
1a,4a,6ab,7a,10aa)] - 3 - ferrocenyl - 1,4,5,6,6a,7,8,9,
0,10a-decahydro-12-methoxy-7-methoxymethyl-7-10a-
dimethylchrysen-1,4-dione (31) (4.1 mg, 3%).
24] A. Yamashita, A. Toy, W. Watt, C.R. Muchmore, Tetrahedron
Lett. 29 (1988) 3403.
(
1
[
[
25] H.S. Sutherland, P.D. Woodgate, accepted for publication.
26] C. Badoli, P. Del Buttero, E. Licandro, S. Maiorana, A. Pa-
pagni, A. Zanotti-Gerosa, J. Organomet. Chem. 486 (1995) 279.
27] K.H. D o¨ tz, T. Sch a¨ fer, F. Kroll, K. Harms, Angew. Chem. Int.
Ed. Engl. 31 (1992) 1236.
28] F. Hohmann, S. Siemoneit, M. Nieger, S. Kotila, K.H. D o¨ tz,
Chem. Eur. J. 3 (1997) 853.
29] M.M. Gleichmann, K.H. D o¨ tz, B.A. Hess, J. Am. Chem. Soc.
118 (1996) 10551.
30] J. Barluenga, F. Aznar, A. Mart ´ı n, S. Garc ´ı a-Granda, E. P e´ rez-
Carre n˜ o, J. Am. Chem. Soc. 116 (1994) 11191.
31] K.H. D o¨ tz, P. Tomuschat, Chem. Soc. Rev. 28 (1999) 187.
32] S.A. Eastham, J. Herbert, J.E. Painter, P. Patel, P. Quayle,
Synlett (1998) 61.
[
[
[
[
4
. Supplementary material
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC no. 156246 for compound 27.
Copies of this information may be obtained free of
charge from The Director, CCDC, 12 Union Road,
Cambridge CB2 1EZ, UK (Fax: +44-1223-336033;
e-mail: deposit@ccdc.cam.ac.uk or www: http://
www.ccdc.cam.ac.uk).
[
[
[33] S. Chamberlain, M.L. Waters, W.D. Wulff, J. Am. Chem. Soc.
16 (1994) 3113.
[
1
34] S. Top, H. El Hafa, A. Vessi e` res, J. Quivy, J. Vaissermann,
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