Synthesis and alkyne-coupling chemistry of cyclomanganated 1- and 3-acetylindoles, 3-formylindole and analogues

Article abstract of DOI:10.1016/j.jorganchem.2005.09.049

The syntheses are reported of new cyclomanganated indole derivatives (1-acetyl-κO-indolyl-κC ²)dicarbonylbis(trimethylphosphite)manganese (2), (1-methyl-3-acetyl-κO-indolyl-κC²)tetracarbonylmanganese (4), (3-formyl-κO-indolyl-κC²)tetracarbonylmanganese (5a) and (1-methyl-3-formyl-κO-indolyl-κC ²)tetracarbonylmanganese (5b). The unusually complicated crystal structure of 5b has been determined, the first for a cyclomanganated aryl aldehyde. The preparations of a mitomycin-related pyrrolo-indole and related products by thermally promoted and oxidatively (Me₃NO) initiated alkyne-coupling reactions of the previously known complex (1-acetyl-κO-indolyl-κC²)tetracarbonylmanganese (1) are reported for different alkynes and solvents. X-ray crystal structures are reported for the dimethyl acetylenedicarboxylate coupling product of 1 (dimethyl 1-methyl-l-hydroxypyrrolo[1,2a]-indole-2,3-dicarboxylate; 6a), and an unusually-cyclised triple insertion product 8 from the coupling of acetylene with 4, in which a cyclopentadiene moiety is η ³-allyl-coordinated to Mn through only one double bond and an exocyclic carbon, but which rearranges on heating to an η ⁵-cyclopentadienyl complex.

Full text of DOI:10.1016/j.jorganchem.2005.09.049

Journal of Organometallic Chemistry 691 (2006) 667–679
www.elsevier.com/locate/jorganchem
Synthesis and alkyne-coupling chemistry of cyclomanganated
- and 3-acetylindoles, 3-formylindole and analogues
1
Gary J. Depree , Lyndsay Main , Brian K. Nicholson a,*,
a
a,
*
a
b
Nicholas P. Robinson , Geoffrey B. Jameson
a
Chemistry Department, University of Waikato, Private Bag 3105, Hamilton, New Zealand
Institute of Fundamental Sciences, Massey University, Private Bag, Palmerston North, New Zealand
b
Received 7 September 2005; received in revised form 28 September 2005; accepted 29 September 2005
Available online 11 November 2005
Abstract
2
The syntheses are reported of new cyclomanganated indole derivatives (1-acetyl-jO-indolyl-jC )dicarbonylbis(trimethylphosph-
2
2
ite)manganese (2), (1-methyl-3-acetyl-jO-indolyl-jC )tetracarbonylmanganese (4), (3-formyl-jO-indolyl-jC )tetracarbonylmanganese
(
2
5a) and (1-methyl-3-formyl-jO-indolyl-jC )tetracarbonylmanganese (5b). The unusually complicated crystal structure of 5b has been
determined, the first for a cyclomanganated aryl aldehyde.
The preparations of a mitomycin-related pyrrolo-indole and related products by thermally promoted and oxidatively (Me
tiated alkyne-coupling reactions of the previously known complex (1-acetyl-jO-indolyl-jC )tetracarbonylmanganese (1) are reported for
different alkynes and solvents. X-ray crystal structures are reported for the dimethyl acetylenedicarboxylate coupling product of 1
3
NO) ini-
2
(
dimethyl 1-methyl-l-hydroxypyrrolo[1,2a]-indole-2,3-dicarboxylate; 6a), and an unusually-cyclised triple insertion product 8 from the
3
coupling of acetylene with 4, in which a cyclopentadiene moiety is g -allyl-coordinated to Mn through only one double bond and an
exocyclic carbon, but which rearranges on heating to an g -cyclopentadienyl complex.
5
ꢀ
2005 Elsevier B.V. All rights reserved.
Keywords: Cyclometallation; Manganese; Indoles; Alkyne coupling
1
. Introduction
We have reported in a review [6] the initial finding [7] of
an equivalent reaction of dimethyl acetylenedicarboxylate
Coupling of alkynes with orthomanganated aryl ketones
(DMAD) with the N-acetyl-coordinated manganated
2
to form 1H-inden-1-ols has been reported by us [1,2] and
by LiebeskindÕs group [3], as have the corresponding
alkyne-coupling reactions of orthomanganated N,N-diph-
enylhydrazones of acetophenone and benzaldehyde to
form indenylhydrazines [4]. Cambie et al. [5] subsequently
used these methods to prepare new steroid-related com-
pounds using substrates derived from the natural product
podocarpic acid.
indole
1
[(1-acetyl-jO-indolyl-jC )tetracarbonylmanga-
nese] to form (Scheme 1) the carbinolamine 6a (dimethyl
1-hydroxy-1-methylpyrrolo[1,2a]indole-2,3-dicarboxylate)
whose pyrrolo-indole skeleton matches that of the mitomy-
cin group of antibiotics [8].
Because there is renewed interest in the synthesis of
this class of polycyclic indole derivative [9] we report
more general alkyne-coupling chemistry of 1, its
Mn(CO) [P(OMe) ] analogue 2, and the related 2-
2
3 2
Mn(CO)4 derivatives of 3-acetylindole and N-methyl-3-
acetylindole (3, 4). The report also includes the synthesis
of the new cyclomanganated indole derivatives 2, 4, 5a
and 5b. The complex crystal structure of 5b is reported
*
Corresponding authors. Fax: +64 7 838 4219 (B.K. Nicholson).
E-mail addresses: l.main@waikato.ac.nz (L. Main), b.nicholson@
waikato.ac.nz (B.K. Nicholson).
0
022-328X/$ - see front matter ꢀ 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2005.09.049

668
G.J. Depree et al. / Journal of Organometallic Chemistry 691 (2006) 667–679
3
5
4
2
1
R
3
Mn(CO) 4
1
2
R C
CR
N
N
O
8
1
2
2
R
Me
Me
OH
1
2
1
6a R = R = CO Me
2
1
2
6
b R = R = Ph
Scheme 1.
as well as those of the DMAD coupling product 6a from
and an unusually cyclised triple-acetylene-insertion
2.2. Alkyne coupling chemistry
1
product from 4.
Results for alkyne-coupling reactions are summarized in
Table 1, which, to serve its purpose as a general reactivity
guide, covers some reactions which are unsuccessful under
conditions in which cyclomanganated acetophenones (cf.
[2]) would normally give good yields. For the reactions of
R'
3
3
O
2
Mn(CO)2(P(OMe)3)2
1
with various alkynes, the usual product is of the pyr-
N
rolo-indole type 6, accompanied by varying amounts of
2
Mn(CO)4
O
N
1
1
-acetylindole arising from simple demetallation (entries
–12, 14–22).
Me
R
2
3
4
5
5
R = H; R' = Me
R = R' = Me
R = R' = H
As discussed previously [1–3], the reactions are pre-
a
b
sumed to involve coordination of alkyne to a vacant coor-
dination site after loss of one CO ligand, achieved
thermally [1,2] or by oxidation with trimethylamine oxide
R = Me; R' = H
[
3], followed by insertion of alkyne to give an alkenyl-Mn
product (Scheme 2 for the case of N-acetylindole). Addi-
tion of the manganated carbon to the adjacent acetyl car-
bonyl group gives the O-manganated precursor of the
product, which with adventitious proton source on workup
or chromatography provides the neutral product (carbinol-
amine 6 in the case of N-acetylindole).
2
. Results and discussion
2
.1. Cyclomanganation reactions
Cyclomanganation at the 2-position of indole is rou-
tinely achieved for 3-acetyl-1-methylindole employing
Under thermal activation, by heating under reflux for
the stated periods, generally much poorer yields are
the standard reaction with PhCH Mn(CO)5 in heptane
achieved here with the 2-Mn(CO) derivative of N-acetylin-
2
4
under reflux, as applied earlier to 1-acetyl-, 1-benzoyl-
dole than for the 2-Mn(CO) derivative of acetophenone,
4
and 3-acetyl-indole [10]. Similarly compounds 5a and
with significant material loss through demetallation of
starting material in part responsible. Yields for thermal
activation with 1 are really only acceptable for synthesis
with diphenylacetylene and then only when using petro-
leum spirit or benzene as solvent (entries 5 and 6).
2-Hexyne, which gives acceptable indenol yields with
cyclomanganated acetophenone [2], fails altogether to do
so with 1 under thermal activation (entries 9–12).
With oxidative activation using trimethylamine oxide in
acetonitrile at room temperature, even more demetallation
of starting compound generally occurs. Nevertheless, better
yields of coupling product are obtained for 1 with dimethyl
acetylenedicarboxylate (DMAD; entry 16) than for ther-
mal activation (entry 3), although the reverse applies for
diphenylacetylene (entries 20 and 7). Similar comparisons
apply for reactions conducted in other solvents with these
two alkynes. It should be noted that for 1, when non-polar
solvents have been employed instead of acetonitrile for
5
b were formed from 3-formylindole and its 1-methyl
analogue. These are notable because an aldehyde group
is directing the cyclometallation reaction, which is rela-
tively rare in contrast to the many ketone examples [6].
We note that benzaldehyde does not cyclomanganate
under these conditions, though 4-methoxy- and 4-dimeth-
ylamino-benzaldehyde do so [10]. This unpredictability
occurs again here with only a low yield of 5a (17%)
but a respectable one for 5b (68%). There are no previ-
ous reports of X-ray crystallographically characterized
cyclomanganated aryl aldehydes, so that of 5b is reported
below.
These new compounds complement cyclomanganated
1
-acetylindole (1) and 3-acetylindole (3) as substrates which
are functionalised at the 2-position of the indole nucleus,
which is important because electrophilic substitution, the
common entry to aryl functionalisation, occurs with a
strong preference for the 3-position in indoles.
Me NO activations (benzene, petroleum spirit, and carbon
3

G.J. Depree et al. / Journal of Organometallic Chemistry 691 (2006) 667–679
669
Table 1
Products from alkyne-coupling reactions
1
2
Entry
Reactant (activation)
Alkyne (R , R ) (1.4 mol)
Solvent (reaction time)
Yield%
a
Coupling product
Demetallation product
b
c
1
2
3
4
5
6
7
8
9
1 (Thermal )
CO
2
Me, CO
2
Me
Pet. sp. (5 h)
15 (6a)
1
18
14
61 (6b)
64
22
–
0
0
0
0
16 (7a)
15 (6a)
61
61
33
18
30 (6b)
7
27
0
4
C
6
H
6
(24 h)
MeCN (2.5 h)
CCl
4
(2.5 h)
7
Ph, Ph
Me, Pr
C
6
H
6
(4 h)
13
10
62
25
45
31
81
42
–
27
22
15
20
43
62
40
26
81
13
c
Pet. sp. (5 h)
MeCN (5 h)
CCl
4
(4 h)
d
C
6
H
6
(22 h)
c
d
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
a
Pet. sp. (23 h)
MeCN (2.5 h)
d
d
CCl
4
(4 h)
e
H, H (saturated )
C
6
H
6
(2 h)
f
c
g
1 (Me
3
NO )
CO
2
Me, CO
2
Me
Pet. sp. (24 h )
C
6
H
6
(22 h)
MeCN (8 h)
(24 h )
MeOH (20 h )
(24 h )
MeCN (3 h)
g
CCl
4
g
g
Ph, Ph
Me, Pr
C
6
H
6
g
C
6
H
6
(24 h )
–
–
h
MeCN (3 h )
MeCN (8 h)
i
1 (Li
2
PdCl
4
)
CO
CO
2
Me, CO
Me, CO
2
Me
Me
5 (6a)
b
b
j
2 (Thermal )
2
2
Pet. sp. (30 h)
n.r.
n.r.
j
MeCN (28 h)
MeCN (27 h.)
f
(Me
3
NO )
(87% 2 recov.)
18 (6b)
–
–
8
b
c
3 (Thermal )
Ph, Ph
CO Me, CO
Pet. sp. (7 h)
c
2
2
Me
Pet. sp. (26 h)
c
Me, Pr
Ph, Ph
Pet. sp. (6 h)
b
c
4 (Thermal )
Pet. sp. (24 h)
43 (7b)
c
CO
2
Me, CO
2
Me
e
Pet. sp. (24 h)
–
23
18
c
k
H,H (saturated )
Ph, Ph
Pet. sp. (6 h)
17 (8)
f
(Me
3
NO )
MeCN (3 h)
MeCN (3 h)
53 (7b)
–
CO
2
Me, CO
2
Me
N-acetylindole from 1 and 2; 3-acetyl-N-methylindole from 4.
b
c
Under reflux.
B.p. 60–80 ꢁC.
d
e
5
–8% unreacted 1 in this series of reactions.
Acetylene at saturation by continuous bubbling through reaction solution under reflux.
Oxidative activation with Me NO (1.5 mol); room temperature.
3
Plus 40 min reflux for completion.
Under reflux throughout.
f
g
h
i
2 4
With added Li PdCl (1 mol) under reflux.
Only unreacted 2 detectable by IR.
See text for structure.
j
k
tetrachloride), incomplete solubilisation of Me NO was
obtained of a mono-insertion product 7a, in which the ace-
tyl group has been transferred to the alkene side-chain, pre-
sumably via the breakdown of an initial carbinolamine
product like 6a.
3
observed and after initial reaction at room temperature
for 24 h, IR normally indicated some residual manganated
reactant, so reaction mixtures were heated under reflux for
an additional 40 min to ensure complete reaction (entries
1
4, 17, 19, 21). As for thermal activation, 2-hexyne again
4'
3'
fails to give an indenol with Me NO activation either in
benzene (entry 21) or acetonitrile, even under reflux (entry
R1
3
2
'
4
2
2). Attempted activation with Pd(II) using Li PdCl in
2 4
N
3
R2
R
7
'
MeCN failed for 1 with DMAD (entry 23), the yield of
a (5%) being negligible by comparison with that using
2
6
Me
O
Me NO activation in the same solvent.
When 1 was reacted with acetylene (entry 13), no deriv-
ative of type 6 was detected. Instead, a 16% yield was
3
1
2
7a R = R = R = H
1
2
7b R = Me; R = R = Ph

670
G.J. Depree et al. / Journal of Organometallic Chemistry 691 (2006) 667–679
5
4
R1C
CR2
R1
3
2
Mn(CO)4
N
N
8
O
1
R2
Me
Me
6
OH
1
R1C
CR2
+
H on work-up
5
R1
4
R1
3
N
N
R2
O
8
1
2
O[Mn]
R2
[Mn]
Me
Me
Scheme 2. Metal ligands omitted at intermediate stages (symbol [Mn]).
To see whether the reactivity could be changed by alter-
tion then deacetylation at C3 by b-aryl-elimination fol-
lowed by proton transfer to C(3) from N(1) and
recyclisation at the latter to give the O[Mn] precursor of
6b (Scheme 3).
The analogous N-methyl-3-acetylindole complex 4 with
diphenylacetylene also results in deacetylation at C-3 to
form the non-cyclisable enone product 7b, presumably with
the stereochemistry shown (Scheme 3; 43%), and this yield
ing the coordination geometry around the manganese atom,
a substituted derivative of 1 was synthesized by thermal
reaction with excess trimethylphosphite to give the disubsti-
tuted compound 2. Characterisation data is given in the
3
1
experimental section, where the single P resonance, and
the two equally intense m(CO) bands both indicate that
the two phosphine ligands are mutually trans, together with
cis CO groups. This is the same pattern as was found for the
crystallographically characterized di-phosphite substituted
compound derived from cyclomanganated triphenylphos-
phine sulfide [11].
is improved to 53% with Me NO activation (entry 33).
3
Again, however, DMAD does not couple successfully with-
out Me NO (entry 31) or with it (entry 34). Possibly the
3
bulkier phenyl substituents encourage cyclisation to form
the two fused 5-membered rings required for the deacetyla-
tion to occur, a form of the Thorpe-Ingold effect [13].
When there are no alkyne substituents (acetylene; under
continuous flow: see experimental), complex 4 does give an
alternative interesting triple insertion/cyclisation product 8
(17%; entry 32) in which the metal is coordinated to both
Replacement of two of the metal carbonyl ligands by
trimethylphosphite to give the complex 2 serves only to
deactivate the Mn center to coupling, at least for the case
of DMAD tested. Notably, even the use of Me NO for
3
activation resulted in no reaction and since 2 was recovered
in 87% yield (entry 26), little if any oxidation of carbonyl
ligand occurs. Since replacement of two CO ligands by
the poorer p-accepting phosphite ligands will increase the
Mn–CO bond order for the remaining CO ligands, this sug-
3
the oxygen atom of the acetyl group and to an g -allyl
group which is part of a methylene–cyclopentadiene group
attached at the 2-position of the original indole. This five-
membered cyclic species has presumably been formed by
triple-insertion of C H , possibly as shown in Scheme 4.
gests that the reactivity of Me NO with strongly coordi-
3
nated CO is simply lost. It seems unlikely that alkyne
would not coordinate if a metal coordination site were
available as we have observed electron-deficient alkene
2
2
Cyclic products from triple acetylene insertion and cyclisa-
tion have been seen before with cyclomanganated aryl
5
(
5
[
methyl acrylate) insertion in the complex of 3-acetyl-2,
-dimethylthiophene cyclometallated by Mn(CO)2-
P(OMe) ] under thermal conditions [12].
ketones [2] but in those cases six-membered ring g -cyclo-
hexadienyl complexes were formed. In the current case, ste-
ric crowding by the 1- and 3-substituents on the indole ring
may restrict cyclisation to the alternative mode involving
metal-mediated hydride migration as indicated in Scheme
4. A similar mechanism was proposed for an analogous tri-
ple insertion of C H to give the ruthenium complex 10 [14].
3
2
The 3-acetylindole complex 3 fails to give clean coupled
product with DMAD or 2-hexyne (entries 28, 29) but for
diphenylacetylene in petroleum spirit, the same coupled
product 6b as from the 1-acetyl complex 1 (entry 6) is unex-
pectedly obtained, though in comparatively low yield
2
2
The product 8 is not thermally stable and on heat-
(
entry 27). Possibly this occurs (Scheme 3) through cyclisa-
ing achieves what is presumably energetically optimal

G.J. Depree et al. / Journal of Organometallic Chemistry 691 (2006) 667–679
671
Me
5
4
R1
O
3
R1C
CR2
N
Mn(CO)4
8
N
1
2
R2
R
3
or 4
6 (R = H)
Me
OH
R1C
CR2
H+ on work-up
O
Me
Mn]
[
R1
R2
N
R2
N
R
Me
R1
O[Mn]
Me
H
[Mn]O
R1
R2
N[Mn]
Me
R2
N
R1
R
O
β-aryl elimination
R = H only
H
O
Me
R2
R1
[Mn]
+
NMe
Me
H on work-up
R2
N
R = Me
R
R1
7b
O
Scheme 3. Metal ligands omitted at intermediate stages: symbol [Mn].
coordination as the cyclopentadienyl complex 9a (9b on
2.3. Crystal structures
heating in the presence of trimethyl phosphite). Possibly 8
is the product of kinetic control and when heated it reverts
to its precursor (see Scheme 4) from which 9a is formed as
the product of thermodynamic control by an alternative
Mn-mediated hydride migration from the cyclopentadienyl
2
2.3.1. (1-Methyl-3-formyl-jO-indolyl-jC )tetracarbonyl
manganese (5b)
This is the first structural determination for an ortho-
manganated aldehyde. The analysis was complicated by
twinning of the crystal and pseudo-symmetry, but a sensi-
ble refinement was ultimately achieved for the four inde-
pendent molecules in the asymmetric unit. The structure
of one of the molecules is presented in Fig. 1. It has the
expected Mn(CO)4 group attached at C(2) (systematic
numbering) of the indole ring and to the formyl oxygen
atom to give a five-membered ring. This manganacyclic
ring is planar, and the average Mn–C and Mn–O bond
0
to benzylic carbon (position 1 ) of 9a. Thermally promoted
migration of this general type has long been known for
endo-H in p-cyclohexadienylMn(CO) complexes [15].
3
Me
4
O
3
Mn(CO)x(P(OMe)3)y
2
Ph2P
˚
Ru
lengths [2.003(11) and 2.071(8) A] conform to the usual
7
N
pattern of the former being shorter than the latter. The
C–Mn–O ÔbiteÕ angle of 79.9ꢁ and the C–O–Mn angle of
1
'
2
'
Me
4'
3
'
1
12.9ꢁ are similar to those in the ketone examples, sug-
9
9
a x = 3 y = 0
b x = 2 y = 1
1
0
gesting close parallels. Nothing in the structural

672
G.J. Depree et al. / Journal of Organometallic Chemistry 691 (2006) 667–679
Me
O
Me
[Mn]
O
H
CO
OC
Mn
N
N
Me
H
CO
Me
8
2
HC
CH
Me
Me
O
O
[Mn]
[Mn]
H
H
N
Me
N
Me
Me
Me
O
O
[Mn]
H
[Mn]
H
N
Me
N
Me
Scheme 4. Proposed route to p-allyl complex 8. The structure in brackets represents a transition state for hydride migration (metal ligands are omitted in
intermediates: symbol [Mn]).
features can explain why cyclomanganation of aldehydes is
generally less predictable than for aryl ketones.
a pyrrolo-indole skeleton (Fig. 2). The determination
was limited by a weakly diffracting crystal but overall
features are clear, the key finding being that the reaction
of 1 with alkynes does give the tricyclic core of the mito-
mycin group of antibiotics. Two other pyrrolo-indole
derivatives have been structurally characterized [16], and
the present example matches parameters with those of
2
2
.3.2. Dimethyl 1-methyl-1-hydroxypyrrolo[1,2a]-indole-
,3-dicarboxylate (6a)
This structure was determined to confirm that inser-
tion of the alkyne and cyclisation had occurred to give
C(5)
C(4)
C(10)
O(10)
C(3)
O(11)
C(2)
O(12)
C(6)
C(12)
C(1)
C(7)
C(8)
Mn
N
C(13)
C(14)
C(9)
O(13)
O(14)
2
Fig. 1. The structure of one of the independent molecules of (1-methyl-3-formyl-jO-indolyl-jC )tetracarbonylmanganese (5b). Bond parameters
˚
(
averaged over all four independent molecules) include: bond lengths (A) Mn(1)–C(1) 2.003(11), Mn(1)–O(10) 2.071(8), C(10)–O(10) 1.265(14), C(1)–C(2)
1.43(2), C(2)–C(10) 1.36(2); bond angles (ꢁ): C(1)–Mn(1)–O(10) 79.9(4), Mn(1)–O(10)–C(10) 112.9(7).

G.J. Depree et al. / Journal of Organometallic Chemistry 691 (2006) 667–679
673
O(4)
C(7)
C(5)
C(6)
C(15)
C(8)
C(4)
C(16)
O(5)
O(3)
C(3)
C(2)
N(1)
C(11)
C(10)
C(9)
C(1)
C(13)
O(1)
C(14)
O(2)
C(12)
˚
Fig. 2. The structure of dimethyl 1-methyl-l-hydroxypyrrolo[1,2a]-indole-2,3-dicarboxylate (6a). Bond parameters include: bond lengths (A) N(1)–C(1)
.474(17), N(1)–C(4) 1.401(16), N(1)–C(11) 1.370(17), C(4)–C(5) 1.32(2), C(1)–C(2) 1.53(2), C(2)–C(3) 1.36(2), C(3)–C(4) 1.44(2), C(1)–O(1) 1.406(18);
bond angles (ꢁ) C(1)–N(1)–C(4) 114(1), C(1)–N(1)–C(11) 136(1), N(1)–C(1)–C(2) 98(1).
1
the earlier determinations, within the precision of the
determination.
carbon atom. This is a similar pattern to that observed in
the related ruthenium compound 10 where again the cyclo-
pentadiene-allyl ligand was formed in situ by trimerisation
of acetylene [14].
3
2
.3.3. The g -allyl complex 8
The crystal structure determination revealed the mole-
cule shown in Fig. 3. There is a Mn(CO) group that has
2.3.4. Conclusion
3
remained coordinated to the 3-acetyl group of the indole.
It is also g -coordinated to an allyl moiety that is part of
There are now four routes that have been observed for
reactions of cyclomanganated ketones with alkynes: (i)
monoinsertion followed by addition across the C@O bond
to form a five-membered ring as for 6a; (ii) monoinsertion
followed by acetyl-group migration to form an enone
group as in 7b; (iii) triple insertion and cyclisation to give
3
a methylene–cyclopentadiene group attached at C(2) of
the indole. This group has clearly been formed by linking
of three molecules of C H as discussed earlier. For the
2
2
allyl group the exocyclic C(8)–C(9) bond is significantly
5
˚
longer, 1.442(6) A, than the internal one C(9)–C(10),
a six-membered g -cyclohexadienyl manganese complex;
(iv) triple insertion and cyclisation to a five-membered ring
˚
1
.376(6) A, with the manganese atom closest to the external
C(1)
C(12)
C(13)
C(7)
C(7a)
C(6)
C(5)
N(1)
C(9)
C(11)
C(2)
C(10)
C(8)
O(1)
C(3)
C(4)
C(3a)
O(14)
O(15)
C(31)
Mn(1)
C(32)
O(16)
3
˚
Fig. 3. The structure of the g -allyl manganese complex 8. Bond parameters include: bond lengths (A) Mn(1)–O(1) 2.052(3), Mn(1)–C(8) 2.145(4), Mn(1)–
C(9) 2.155(4) Mn(1)–C(10) 2.280(5), C(31)–O(1) 1.260(5), C(8)–C(9) 1.442(6), C(9)–C(10) 1.376(6), C(9)–C(13) 1.520(6), C(10)–C(11) 1.461(6), C(11)–
C(12) 1.336(7), C(12)–C(13) 1.490(7); bond angles (ꢁ) Mn(1)–O(1)–C(31) 132.8(3), C(8)–C(9)–C(10) 128.4(4).

674
G.J. Depree et al. / Journal of Organometallic Chemistry 691 (2006) 667–679
methylene–cyclopentadienyl group as for 8. So far (ii) and
iv) have only been observed with the acetyl-indoles, as
reported herein, for reasons that are not yet apparent. It
is clear that these reactions have potential for the synthesis
of complex hetero-polycyclic compounds from simple
starting materials.
(40 mL) and the solution degassed and flushed with nitro-
gen twice. After heating under reflux under nitrogen for
90 min, the heptane was removed under vacuum. P.l.c.
(1:4 v/v CH C1 /petroleum spirit) gave a broad yellow
band which yielded 1 (439 mg, 69%), recrystallised from
petroleum spirit as yellow plates, m.p. (dec.) 148 ꢁC (1it.
(
2
2
1
12 ꢁC [10]). IR (CHC1 ): m(CO) 2090 (m), 2007 (vs,
3
ꢀ
1 1
3
. Experimental
br), 1946 (s) cm . H NMR (300.13 MHz) (CDCl ): d
3
7.52 (d, J = 8.0 Hz, 1H, H-7), 7.42 (d, J = 7.5 Hz, 1H,
3
.1. General
H-4), 7.26 (m, 1H, H-5), 7.12 (m, 1H, H-6), 6.84 (s, 1H,
H-3), 2.79 (s, 3H, 1-COCH3). C NMR (75.47 MHz)
1
3
Petroleum spirit (b.p. 60–80 ꢁC) and all other solvents in
(CDC1 ): d 220.1 (s, br, CO), 212.3 (s, br, CO), 209.8
3
preparative and chromatographic work were of analytical
grade. Other commercial reagents were used without puri-
fication. Dimethyl acetylenedicarboxylate is abbreviated as
DMAD in the text. P.l.c. refers to preparative layer chro-
matography on silica (Merck Kieselgel 60PF254: 200
(s, br, 2 · CO), 178.4 (s, 1-COMe), 172.6 (s, C-2), 137.6
(s, C-7a), 137.2 (s, C-3a), 124.7 (d, C-5), 121.9 (d, C-3),
121.3 (d, C-6), 118.5 (d, C-4), 112.1 (d, C-7), 22.8 (q,
COCH3).
2
·
200 · 2 mm) and t.l.c. to thin layer chromatography on
3.2.2. (1-Acetyl-jO-indolyl-jC )dicarbonylbis(trimethyl-
phosphite)manganese (2)
foil-backed silica (Merck Kieselgel 60PF254). Infrared spec-
tra (in chloroform) were recorded on a Digilab FTS-45
FTIR instrument and NMR spectra on a Bruker AC300
2
(1-Acetyl-jO-indolyl-jC )tetracarbonylmanganese (1;
203 mg, 0.623 mmol), and trimethylphosphite (0.37 mL,
3.14 mmol) were added to nitrogen-saturated heptane.
The solution was heated under reflux for 5 h and the hep-
tane was removed under vacuum. The yellow residue gave
by p.l.c. (1:2 ethyl acetate/hexane) 2 (294 mg, 91%) as a
yellow solid which crystallised from CH Cl /pentane as
instrument in CDCl ; primed numbers used on structures
3
for convenience to distinguish NMR signals of H or C
atoms are not associated with systematic numbering; nor
are systematic numbers used in labeling atoms in crystal
structure diagrams. Electrospray mass spectrometry
2
2
(
ESMS) was carried out on a VG Platform II machine,
yellow blocks, m.p. 133–134 ꢁC. Anal. Found: C, 41.93;
with MeOH as mobile phase.
H, 4.99; N, 2.66; C H O MnNP calcd: C, 41.79; H,
1
8
26
9
2
Benzylpentacarbonylmanganese was prepared by the
standard method of Closson et al.[17], m.p. 36–37 ꢁC (lit.,
5.07; N, 2.71%. IR (CHCl ): m(CO) 1948 (s), 1869
3
ꢀ1
1
(s) cm
.
H NMR (300.13 MHz) (CDCl ): d 7.46 (d,
3
3
7.5–38.5 ꢁC [17]), IR (CHC1 ): m(CO) 2108 (m), 2012
J = 8.0 Hz, 1H, H-7), 7.30 (d, J = 7.7 Hz, 1H, H-4), 7.16
3
ꢀ
1
4
(
vs, br), 1993 (s) cm
.
(m, 1H, H-5), 6.95 (m, 1H, H-6), 6.83 (t, J = 4.1 Hz,
PH
3
To prepare 1-methyl-3-acetylindole, 3-acetylindole
1.00 g, 6.28 mmol), potassium carbonate (4.42 g, 32.0
1H, H-3), 3.54 (t, J = 5.3 Hz, 18H, P(OCH ) ), 2.71
(s, 3H, 1-COCH ). C NMR (75.47 MHz) (CDCl ): d
228.5 (s, J = 33.8 Hz, br, CO), 220.0 (s, J = 27.9 Hz,
PC PC
br, CO), 188.1 (s, J = 36.4 Hz, C2), 176.4 (s, COMe),
PH
3
3 3
1
(
3
3
2
2
mmol) and methyl iodide (0.51 mL, 8.19 mmol) were
heated under reflux in dry acetone (70 mL) overnight.
The solution was filtered and volatiles removed under vac-
uum. The residue was dissolved in ether (40 mL), washed
successively with water (50 mL), aqueous NaOH (20 mL;
2
PC
138.0 (s, C-7a), 137.0 (s, C-3a), 123.6 (d, C-5), 120.7 (d,
3
JPC = 5.5 Hz, C-3), 118.9 (d, C-6), 117.0 (d, C-4), 111.6
3
1
(d, C-7), 51.7 (q, P(OCH ) ), 22.6 (q, COCH ).
P
3
3
3
ꢀ
1
2
mol L ), and water (50 mL), then dried over MgSO4.
NMR (36.23 MHz) (CDC1 ): d 179.0. ESMS: m/z 518
3
+
After filtering, the ether was removed to give 1-methyl-3-
(M + H) .
acetylindole as a creamy brown crystalline solid (0.90 g,
1
2
8
3%), m.p. 108–109 ꢁC (lit. 108 ꢁC [18]). H NMR: d 8.37
3.2.3. (3-Acetyl-jO-indolyl-jC )tetracarbonylmanganese
(3)
(
m, 1H, H-4), 7.66 (s, 1H, H-2), 7.30 (m, 3H, H-5, H-6,
1
3
H-7), 3.81 (s, 3H, 1-CH ), 2.50 (s, 3H, 3-COCH ).
C
Prepared similarly to 1 was 3 (81%), yellow needles from
chloroform/pentane, m.p. (dec.) 144 ꢁC. The compound
was previously [19] isolated only as an oil. Anal. Found:
C, 51.97; H, 2.21; N, 4.32; C H O NMn calcd: C, 51.71;
3
3
NMR: d 193.0 (s, 3-COMe) 137.5 (s, C-7a), 135.9 (d, C-2),
26.2 (s, C-3a), 123.3 (d, C-5 or C-6), 122.5 (d, C-4, C-5
or C-6), 116.8 (s, C-3), 109.7 (d, C-7), 33.4 (q, N-CH ),
1
3
14
8
5
+
2
3
3
7.6 (q, COCH ). GCMS: m/z 173 (M ).
H, 2.48; N, 4.31%. IR (CHCl ): m(CO) 2092 (m), 2010
3
vs, br), 1943 (s) cm . H NMR (300.13 MHz) (CDC1 ):
d 9.47 (s, br, 1H, NH), 7.64 (d; J = 7.4 Hz, 1H, H-4),
.41 (d, J = 8.2 Hz, 1H, H-7), 7.21 (m, 2H, H-5, H-6),
2.65 (s, 3H, COCH3). C NMR (75.47 MHz) (CDC1 ): d
220.2 (s, br, CO), 212.6 (s, br, CO), 210.8 (s, C-2), 209.7
(s, br, 2 · CO), 201.9 (s, COMe), 143.7 (s, C-7a), 129.5 (s,
C-3), 126.5 (s, C-3a), 122.2 (d, C-5), 121.9 (d, C-6), 117.3
(d,C4), 110.5 (s, C-7), 25.0 (q, COCH3).
3
ꢀ1 1
(
3
.2. Preparation of cyclomanganated complexes
7
1
3
.2.1. The standard cyclomanganation procedure is as
3
2
described for 1-acetylindole: (1-acetyl-jO-indolyl-jC )-
tetracarbonylmanganese (1)
1
-Acetylindole (313 mg, 1.96 mmol) and PhCH Mn
2
(
CO)5 (630 mg, 2.20 mmol) were dissolved in heptane

G.J. Depree et al. / Journal of Organometallic Chemistry 691 (2006) 667–679
675
3
.2.4. (1-Methyl-3-acetyl-jO-indolyl-
times. The mixture was heated under reflux under nitrogen,
variously from 2 h to several days, the extent of reaction
being monitored by thin layer chromatography and/or IR
spectroscopy. At the completion of reaction the solvent
was removed under vacuum and the residue subjected to
p.l.c. with ethyl acetate/petroleum spirit as eluent. Minor
bands were not extracted.
2
jC )tetracarbonylmanganese (4)
Prepared similarly from 3-acetyl-1-methylindole was 4
(
84%), yellow blocks from CHC1 /pentane, m.p. 142–
3
1
44 ꢁC. Anal. Found: C, 53.26; H, 2.67; N, 4.14; C H
5
1
5
10
O NMn calcd: C, 53.12; H, 2.97; N, 4.13%. IR (CHC1 ):
m(CO) 2091 (m), 2010 (vs), 1943 (s) cm
3
ꢀ
1
1
.
H NMR
(
300.13 MHz) (CDC1 ): d 7.60 (m, 1H, H-4), 7.35 (m, 1H,
In the cases of reactions with acetylene the same proce-
dure was used except that acetylene was continuously
replenished by bubbling it through the reaction solution
(ca. 20 mL) for the duration of the reaction. As it is known
that (at 4 ꢁC) 20 mL of benzene dissolves about
3
H-7), 7.23 (m, 2H, H-5, H-6), 4.05 (s, 3H, 1-CH ), 2.61 (s,
3
(
2
1
3
1
3
H, 3-COCH3). C NMR (75.47 MHz) (CDCl ): d 220.7
3
s, br, CO), 213.3 (s, br, CO), 212.1 (s, C-2), 209.7 (s, br,
· CO), 200.7 (s, COMe), 144.8 (s, C-7a), 127.7 (s, C-3),
27.0 (s, C-3a), 122.1 (d, C-5), 121.5 (d, C-6), 117.2 (s,
ꢀ
1
0.55 mmol mL of acetylene, and 20 mL of cyclohexane
ꢀ1
C-4), 109.5 (d, C-7), 35.7 (q, 1-CH ), 24.8 (q, COCH ).
(a model for petroleum spirit) about 0.35 mmol mL [20],
acetylene would be in continuous large excess of the mang-
anated complex (<0.5 mmol in 20 mL solvent) were the
reactions run at this temperature, but we can find no data
on acetylene solubility in benzene or alkanes nearer their
boiling points. Irrespective of its molar excess at any time,
however, acetylene is continuously replenished as it reacts.
3
3
2
3
(
.2.5. (3-Formyl-jO-indolyl-jC )tetracarbonylmanganese
5a)
Similarly prepared from PhCH Mn(CO) and indole-3-
2
5
carboxaldehyde under reflux in heptane but only in low
yield after 19 h was 5a (17%), yellow needles from diethyl
ether/pentane, m.p. 148–149 ꢁC. Anal. Found: C, 50.43;
H, 1.89; N, 4.55; C H O NMn calcd.: C, 50.19; H, 1.94;
N, 4.50%. IR (CHC1 ): m(CO) 2094 (m), 2012 (vs, br),
1
13
6
5
3
.3.1.2. Oxidatively induced with Me NO. The standard
3
3
method is as in Section 3.3.1.1 except that only the ortho-
manganated compound was dissolved initially. After flush-
ing with nitrogen, trimethylamine-N-oxide (ca. 1.4 mol
equiv.) was added and the solution was stirred under nitro-
gen for 15 min (development of an intense yellow colour).
The alkyne was then added and the mixture was stirred at
ambient temperature for 3–24 h. The extent of reaction
was monitored by thin layer chromatography; if any ortho-
manganated compound still remained after 24 h the solution
was heated under reflux for approximately an extra 40 min,
by which time t.l.c. showed the reaction to be complete.
ꢀ
1
1
947 (s) cm . H NMR (300.13 MHz) (CDCl ): d 9.66
3
(
s, br, 1H, H-1), 9.29 (s, 1H, CHO) 7.68 (m, 1H, H-4),
1
3
7
.40 (m, 1H, H-7), 7.21 (m, 2H, H-5, H6). C NMR
(
75.47 MHz) (CDC1 ): d 220.8 (s, br, CO), 215.9 (s, C-2),
3
2
1
12.7 (s, br, CO), 209.4 (s, br, 2 · CO), 190.2 (d, CHO),
43.8 (s, C-7a), 131.8 (s, C-3), 126.3 (s, C-3a), 122.8 (d,
C-5 or C-6), 122.6 (d, C-5 or C-6), 117.9 (d, C-4), 110.6
d, C-7).
(
2
3
.2.6. (1-Methyl-3-formyl-jO-indolyl-jC )-
tetracarbonylmanganese (5b)
Similarly prepared from PhCH Mn(CO) and 1-methy-
2
5
lindole-3-carboxaldehyde over 75 min was 5b (68%),
3.3.2. Thermally promoted reactions of (1-acetyl-jO-
indolyl-jC )tetracarbonylmanganese (1)
2
orange blocks from CHC1 /pentane, m.p. 118–120 ꢁC.
3
Anal. Found: C, 51.82; H, 2.09; 4.36; C H O NMn calcd:
3.3.2.1. With dimethyl acetylenedicarboxylate to form
dimethyl 1-methyl-1-hydroxypyrrolo[1,2a]-indole-2,3-dicarb-
oxylate (6a). Following the standard procedure above, 1
(81 mg, 0.25 mmol) and DMAD (60 mg, 0.42 mmol)
under reflux in petroleum spirit for 5 h followed by
p.l.c. (1:3 ethyl acetate/petroleum spirit) gave 1-acetylin-
dole (11 mg, 27%) and 6a (12 mg, 15%), a yellow oil
1
4
8
5
C, 51.71; H, 2.48; N, 4.31%. IR (CHC1 ): m(CO) 2093 (m),
3
ꢀ1
1
2
012 (vs, br), 1947 (s) cm
.
H NMR (300.13 MHz)
(
(
CDC1 ): d 9.19 (s, 1H, CHO), 7.65 (m, 1H, H-4), 7.34
3
m, 1H, H-7), 7.24 (m, 2H, H-5, H-6), 4.08 (s, 3H, CH ).
3
1
3
C NMR (75.47 MHz) (CDC1 ): d 221.4 (s, br, CO),
3
2
1
16.5 (s, C-2), 213.2 (s, br, CO), 209.3 (s, br, 2 · CO),
88.7 (d, CHO), 144.9 (s, C-7a), 130.1 (s, C-3), 127.0 (s,
which crystallised from CH C1 /petroleum spirit as yellow
2 2
1
C-3a), 122.7 (d, C-5 or C-6), 122.3 (d, C-5 or C-6), 117.6
d, C-4), 109.6 (d, C-7), 35.7 (q, 1-CH ). The single crystal
needles, m.p. 98–99 ꢁC. H NMR (300.13 MHz) (CDC1
):
3
0
(
d 7.63 (d, J = 8.0 Hz, 1 H, H-4 ), 7.53 (d, J = 8.2 Hz, 1H,
3
0
0
X-ray structure analysis of 5b is reported below.
H-7 ), 7.26 (t, J = 8.2 Hz, 1H, H-6 ), 7.11 (t, J = 8.0, 1H,
0
0
H-5 ), 6.60 (s, 1H, H-3 ), 3.92 (s, 3H, COOCH ), 3.87 (s,
3
3.3. Coupling reactions of alkynes with cyclomanganated
compounds
3H, COOCH
3
), 3.44 (s, 1H, 1-OH), 1.95 (s, 3H, 1-CH
C NMR (75.47 MHz) (CDCl ): d 163.0 (s, COOMe),
62.9 (s, COOMe), 140.6 (s, C-2), 137.0 (s, C-3), 134.4
3
).
1
3
3
1
0
0
0
3
3
.3.1. Standard methods
.3.1.1. Thermally promoted. The orthomanganated com-
(s, C-7a ), 132.9 (s, C-3a ),132.6 (s, C-2 ), 124.4 (d, C-
6 ), 122.9 (d, C-4 ), 120.6 (d, C-5 ), 110.6 (d, C-7 ), 99.8
0
0
0
0
0
pound (100 mg) and alkyne (1.2–2.2 mol equiv.) were dis-
solved in solvent (20 mL; analytical grade), and the
solution was degassed and flushed with nitrogen several
(d, C-3 ), 90.2 (s, C-1), 52.9 (q, OCH
3
), 52.6 (q, OCH
). The single crystal X-ray structure deter-
mination of 6a is reported below.
),
3
24.1 (q, 1-CH
3

676
G.J. Depree et al. / Journal of Organometallic Chemistry 691 (2006) 667–679
Corresponding outcomes in other solvents for the reflux
period stated: benzene (24 h): 1% 6a; MeCN (2.5 h): 18%
(107 mg, 0.328 mmol), Me NO (36 mg, 0.483 mmol) and
DMAD (0.057 mL, 0.464 mmol) in benzene at ambient
3
6
1
a and 4% 1-acetylindole; CCl (2.5 h) 14% 6a and 14%
-acetylindole.
temperature for 22 h then under reflux for 40 min gave 6a
(60 mg, 61%) and 1-acetylindole (12 mg, 22%).
4
Corresponding outcomes in other solvents for the reflux
period stated: petroleum spirit (24 h + 40 min reflux): 50%
6a and 9% 1-acetylindole; MeCN (8 h): 61% 6a and 15% 1-
3
2
.3.2.2. With diphenylacetylene to form 1-methyl-1-hydroxy-
,3-diphenylpyrrolo[1,2a]-indole (6b). Following the
standard procedure for DMAD in Section 3.3.2.1 but using
acetylindole; CCl (24 h + 40 min reflux): 33% 6a and 10%
4
1
0
:4 ethyl acetate/petroleum spirit for p.l.c., 1 (105 mg,
.322 mmol) and diphenylacetylene (82 mg, 0.459 mmol)
1-acetylindole; MeOH (24 h + 40 min reflux): 18% 6a and
43% 1-acetylindole.
in benzene under reflux over 4 h gave 6b (66 mg, 61%) as
an off-white solid which crystallised from CH C1 /pentane
3.3.3.2. With diphenylacetylene to form 1-methyl-1-hydroxy-
2,3-diphenylpyrrolo[1,2a]-indole-2,3-dicarboxylate (6b).
Following the standard procedure in Section 3.3.2.1, 1
2
2
1
as chunky cream crystals, m.p. 183–184 ꢁC. H NMR
0
(
7
(
6
300.13 MHz) (CDC1 ): d 7.62 (d, J = 7.9 Hz, 1H, H-4 ),
3
0
.57 (d, J = 8.0 Hz, 1H, H-7 ), 7.50 (m, 4H, Ar-H), 7.35
(103 mg, 0.316 mmol), Me NO (37 mg, 0.490 mmol) and
3
0
0
m, 6H, Ar-H), 7.22 (m, 1H, H-6 ), 7.11 (m, 1H, H-5 ),
diphenylacetylene (87 mg, 0.485 mmol) in benzene at ambi-
ent temperature for 22 h then under reflux for 40 min gave
6b (32 mg, 30%) and 1-acetylindole (31 mg, 62%).
Corresponding outcome: MeCN (3 h ambient): 7% 6b
plus 80% 1-acetylindole.
0
.41 (s, 1H, H3 ), 2.78 (s, br, 1H, 1-OH), 1.82 (s, 3H, 1-
CH3). C NMR (75.47 MHz)(CDC1 ): d 145.3 (s), 143.3
1
3
3
(
1
(
5
1
s), 133.7 (s), 133.3 (s), 133.2 (s), 132.9 (s), 131.5 (s),
29.3 (d), 129.0 (d), 128.6 (d), 128.5 (d), 128.4 (d), 128.3
0
0
s), 128.1 (d), 122.6 (d, C-6 ), 121.9 (d, C-4 ), 119.9 (d, C-
0
0
0
), 110.1 (d, C-7 ), 95.3 (d, C-3 ), 91.6 (s, C-1), 23.8 (q,
3.3.3.3. With 2-hexyne. The standard procedure in Sec-
tion 3.3.2.1 applied to 2-hexyne in both benzene and in ace-
tonitrile, gave no analogues of 6, only 1-acetylindole (52%
in benzene; 81% in acetonitrile).
-CH ). Also obtained was 1-acetylindole (7 mg, 13%).
3
Corresponding outcomes in other solvents for the reflux
period stated: petroleum spirit (5 h): 64% 6b and 10% 1-
acetylindole; MeCN (5 h): 22% 6b and 62% 1-acetylindole;
CCl (4 h) 6b not formed; 25% 1-acetylindole.
3.3.4. Attempted Pd(II)-promoted coupling reaction of
2
4
(
1-acetyl-jO-indolyl-jC )tetracarbonylmanganese and
3
.3.2.3. With 2-hexyne: attempted preparation of 1-methyl-l-
dimethyl acetylenedicarboxylate
PdC1 (61 mg, 0.343 mmol) and LiCl (61 mg, 1.44 mmol)
were stirred in dry acetonitrile (15 mL) for 2 h to solubilise
hydroxy-2,3-diethyllpyrrolo[1,2a]-indole (6b). The stan-
dard procedure for DMAD in Section 3.3.2.1 was unsuc-
cessful in giving any coupling product. Apart from small
quantities of residual 1 the only material separated by
p.l.c. using 1:4 ethyl acetate/petroleum spirit was demetal-
lated product 1-acetylindole: Benzene (22 h): 7% residual 1
plus 45% 1-acetylindole; petroleum spirit (23 h): 8% 1 and
2
the PdC12 as Li [PdC1 ]. 1 (108 mg, 0.332 mmol) and
2
4
DMAD (0.057 mL, 0.464 mmol) were added and the mix-
ture was heated under reflux for 20 h. The mixture was fil-
tered to remove black precipitate, the filtrate passed
through a short silica column and solvent evaporated.
P.l.c. (1:3 ethyl acetate/petroleum spirit) gave dimethyl 1-
methyl-l-hydroxypyrrolo[1,2a]-indole-2,3-dicarboxylate (6a;
3
1% 1-acetylindole; MeCN (2.5 h): 8% 1 and 81% 1-acety-
lindole; CCl (22 h): 5% 1 and 42% 1-acetylindole.
4
6
mg, 5%) and 1-acetylindole (7 mg, 13%).
3
(
.3.2.4. With acetylene to form 4-(indol-2-yl)but-3-en-2-one
7a). 1 (139 mg, 0.427 mmol) and excess acetylene (con-
2
3.3.5. Reactions of (1-acetyl-jO-indolyl-jC )dicarbonylbis-
(trimethylphosphite)manganese (2) with DMAD
2 and DMAD (1.4 mol) under reflux in petroleum spirit
(30 h) or acetonitrile (28 h) showed by t.l.c. only unreacted
orthomanganated ketone.
tinuous flow) under reflux in benzene (40 mL) over 2 h gave
Mn (CO) (3 mg, 5%) and 7a (13 mg, 16%) as a yellow oi1,
2
10
+
1
identified only by spectra: MS (M ) 185. H NMR: d 7.22
m, 4H, H-4-7), 6.80 (s, 1H, H-3), 6.76 (d, J = 12.3 Hz, 1H,
(
0
0
H-1 ), 6.12 (d, J = 12.6 Hz, 1H, H-2 ), 2.35 (s, 3H, CH ).
When the reaction was repeated in acetonitrile at ambi-
ent temperature but with 1.4 mol Me NO for 27 h, p.l.c.
(1:2 hexane/ethyl acetate) gave unreacted 2 (87%) and 1-
3
1
3
C NMR: d 199.4 (C@O), 137.4 (C-7a), 134.4 (C-2),
3
0
1
4
33.9 (C-1 ), 128.1 (C-3a), 125.3, 121.5, 120.3, 120.1 (C-
0
1
,5,6,2 ), 112.4, 112.3 (C-3,7), 31.7 (CH ). H NMR data
acetylindole (8%).
3
match those previously reported for 4-(indol-2-yl)but-3-
en-2-one [21].
3.3.6. Thermally promoted reactions of (3-acetyl-jO-indolyl-
jC )tetracarbonylmanganese (3) in petroleum spirit
2
3
.3.3. Me NO-activated reactions of (1-acetyl-jO-indolyl-
The manganocycle 3 (104 mg, 0.320 mmol) and diphenyl-
acetylene (82 mg, 0.462 mmol) under reflux in petroleum
spirit for 7 h gave by p.l.c. (1:4 ethyl acetate/petroleum
spirit) 1-methyl-l-hydroxy-2,3-diphenylpyrrolo[1,2a]indole
(6b; 20 mg, 18%).
3
2
jC )tetracarbonylmanganese (1)
.3.3.1. With dimethyl acetylenedicarboxylate to form
dimethyl1-methyl-1-hydroxypyrrolo[1,2a]-indole-2,3-dicarb-
3
oxylate (6a). Following the standard procedure above, 1

G.J. Depree et al. / Journal of Organometallic Chemistry 691 (2006) 667–679
677
For the corresponding reaction with DMAD (after
6 h) and 2-hexyne (6 h), t.l.c. showed the presence of
3.4. Rearrangement reactions of 8
2
unreacted starting material and no other major organic
products.
3.4.1. In heptane under reflux
8 (46 mg, 0.117 mmol) was heated under reflux in hep-
tane (15 mL) for 24 h. The residue was chromatographed
(p.l.c. 1:3 ethyl acetate/petroleum spirit) to give (1-methyl-
3-acetyl-2-indolylmethylcyclopentadienyl)tricarbonylman-
ganese (9a; 24 mg, 52%) as an opaque oil, identified
2
3
tetracarbonylmanganese (4)
.3.7. Reactions of (1-methyl-jO-acetyl-2-indolyl-jC )
3
.3.7.1. With diphenylacetylene. 4 (103 mg, 0.303 mmol]
+
and diphenylacetylene (82 mg, 0.461 mmol) under reflux
in petroleum spirit over 24 h gave 4-(1-methyl-2-indolyl)-
spectrally only. MS: MH 390.0543; C H O NMn calcd.:
2
0
17
4
MH, 390.0538. IR (CHC1 ): m(CO) 2021 (s), 1937 (vs, br).
3
1
3
4
,4-diphenylbut-3-en-2-one (presumably the Z-isomer 7b;
H NMR (300.13 MHz) (CDC1 ): d 7.92 (m, 1H, H-4),
3
6 mg, 43%) which crystallized from CHC1 /pentane as
7.40 (m, 1H, H-7), 7.30 (m, 2H, H-5, H-6), 4.87 (t,
3
0 0
chunky yellow crystals, m.p. 160–162 ꢁC. Anal. Found:
J = 2.1 Hz, 2H, H-3 or H-4 ), 4.57 (t, J = 2.1 Hz, 2H, H-
+
1
0
0
0
M
(
7
3
351.1620; C H NO calcd: M, 351.1623. H NMR
3 or H-4 ), 4.24 (s, 2H, H-1 ), 3.83 (s, 3H, N–CH ), 2.73
2
5
21
3
0
13
300.13 MHz) (CDC1 ): d 7.63 (d, J = 7.8 Hz, 1H, H-4 ),
.25–6.99 (m, 13H, Ar–H), 6.68 (s, 1H, H-3 ), 3.34 (s,
H, N-CH ), 2.09 (s, 3H, COCH ). C NMR (75.47
(s, 3H, COCH3). C NMR (75.47 MHz) (CDC1 ): d
3
3
0
224.9 (s, CO), 194.3 (s, COMe), 145.1 (s, C-2), 136.8 (s,
C-7a), 125.9 (s, C-3a), 122.7 (d, C-5 or C-6), 122.4 (d, C-
5 or C-6), 120.8 (d, C-4), 114.1 (s, C-3), 110.2 (d, C-7),
1
3
3
3
MHz) (CDC1 ): d 205.2 (s, COMe), 146.0 (s), 139.2 (s),
3
0
0
0
1
1
38.6 (s),138.2 (s), 137.4 (s), 135.1 (s), 130.5 (d, Ar–C),
100.9 (s, C-2), 84.4 (d, C-3 or C-4 ), 81.2 (d, C-3 or C-
0 0
4 ), 31.9 (q, CH ), 30.0 (q, CH ), 24.4 (t, C-1 ). ESMS:
3 3
30.2 (d, Ar–C), 128.6 (d, ArC), 128.3 (d, Ar–C), 128.0
0
+
+
(
d, Ar–C), 127.8 (s), 122.7 (d, Ar–C), 121.1 (d, C4 ),
m/z 407 (M + NH ) , 390 (M + H) .
4
0
1
19.9. (d, Ar–C), 109.5 (d, Ar–C), 106.7 (d, C-3 ), 31.1
0
(
q, COCH ), 30.8 (q, 1 -CH ).
3.4.2. In the presence of P(OMe)3
3
3
4
(102 mg, 0.302 mmol), Me NO (35 mg, 0.462 mmol)
8 (20 mg, 0.051 mmol) and trimethylphosphite (50 mL,
0.424 mmol) under reflux in heptane (10 mL) for 4.5 h fol-
lowed by p.l.c. (3:7 ethyl acetate/petroleum spirit) gave
(1-methyl-3-acetyl-2-indolylmethylcyclopentadienyl)dicar-
bonyl(trimethylphosphite)manganese (9b; 12 mg, 50%) as a
3
and diphenylacetylene (77 mg, 0.434 mmol) at ambient
temperature in acetonitrile for 3 h gave 7b (57 mg, 53%)
and 1-methyl-3-acetylindole (9 mg, 18%).
+
3
.3.7.2. With DMAD. 4 (100 mg, 0.296 mmol] and
yellow oi1, identified by spectra only. MS: M , 485.0807;
DMAD (0.055 mL, 0.448 mmol) under reflux in petroleum
spirit for 24 h gave unreacted g -(1-methyl-3-acetyl-2-indo-
lyl)tetracarbonylmanganese (26 mg, 26%) and 1-methyl-3-
acetylindole (12 mg, 23%).
C H O NPMn calcd.: M, 485.0800. IR (CHC1 ): m(CO)
2
2
25
6
3
2
1
1946 (s), 1877 (s). H NMR (300.13 MHz) (CDC1 ): d 7.93
3
0
(m, 1H, H-4 ), 7.36 (m, 1H, H-7), 7.30 (m, 2H, H-5, H-6),
4.65 (m, 2H, H-3 or H-4 ), 4.34 (m, 2H, H-3 or H-4 ),
4.27 (s, 2H, H-1 ), 3.86 (s, 3H, N–CH ), 3.60 (d,
JPH = 11.6 Hz, 9H, P(OCH ) ), 2.71 (s, 3H, COCH );
0
0
0
0
0
3
4 (104 mg, 0.308 mmol), Me NO (35 mg, 0.469 mmol)
3
3
3
13
and DMAD (0.057 mL, 0.464 mmol) were stirred at
ambient temperature in acetonitrile for 3 h. The residue
was chromatographed (p.l.c. 1:1 ethyl acetate/petroleum
spirit) to give several minor bands that were not
identified.
C
3 3
3
NMR (75.47 MHz) (CDC1 ): d 230.0 (s, CO), 229.5 (s,
3
CO), 194.2 (s, COMe), 146.2 (s, C-2), 136.8 (s, C-7a), 126.1
(s, C-3a), 122.4 (d, C-5 or C-6), 122.2 (d, C-5 or C-6), 120.8
0
(d, C-4), 113.8 (s, C-3), 110.1 (d, C7), 98.9 (s, C-2 ), 82.2 (d,
0
0
0
0
C-3 or C-4 ), 80.6 (d, C-3 or C-4 ), 51.6 (q, P(OCH ) ),
3
3
0
31.8 (q, CH ), 30.4 (q, CH ), 24.7 (t, C-1 ). P NMR
3 3
(36.23 MHz) (CDC1 ): d 209.9. ESMS: m/z 486 (M + H) .
31
3
.3.7.3. With acetylene. 4 (200 mg, 0.303 mmol) under
+
reflux in acetylene-saturated petroleum spirit for 6 h fol-
lowed by p.l.c. (1:4 ethyl acetate/petroleum spirit) gave the
cyclopentene-fused allyl complex 8 (39 mg, 17%) which crys-
tallised from chloroform/pentane as chunky orange crystals,
3
4. Single crystal X-ray structure determinations
m.p. 135–137 ꢁC. IR (CHC1 ): m (CO) 2013 (s), 1932 (s, br),
For all structures data were collected on a Nicolet R3
diffractometer using standard procedures. Data were cor-
rected for absorption using an empirical method based
on a series of /-scans for 8.
3
ꢀ
1 1
1
899 (s, br) cm . H NMR (300.13 MHz) (CDC1 ): d 7.65
3
(
d, J = 7.3 Hz, 1H, H-4), 7.37 (d, J = 7.5 Hz, 1H, H-7),
.30 (m, 2H, H-5, H-6), 6.77 (d, J = 4.8 Hz, 1H), 6.15 (d,
7
J = 4.8 Hz, 1H), 5.11 (s, 1H), 4.06 (s, 3H), 3.59 (d,
J = 22.5 Hz, 1H), 3.41 (s, 1H), 3.20 (d, J = 22.5 Hz, 1H),
2
4.1. (1-Methyl-3-formyl-jO-indolyl-jC )-
tetracarbonylmanganese (5b)
1
3
2
2
1
9
.56 (s, 3H). C NMR (75.47 MHz) (CDC1 ): d 223.2 (s),
3
22.7 (s), 221.8 (s), 194.3 (s), 153.8 (s), 137.4 (s), 136.4 (d),
28.5 (d), 125.8 (s), 123.0 (d), 122.8 (d), 120.0 (d), 110.0 (d),
5.7 (d), 48.6 (t), 43.2 (d), 30.4 (q), 29.9 (q). This compound
Crystal data: C H MnNO , M 325.15, monoclinic,
space group P2 , a = 9.656(2) A, b = 11.966(2) A, c =
23.486(5) A, b = 101.78(3)ꢁ, V = 2656.5(9) A , Dcalc =
1.626 g cm , Z = 8, l(Mo Ka) = 1.014 mm , orange
1
4
8
5
r
˚
˚
1
3
˚
˚
(
8) was identified by a single crystal X-ray structure analysis
ꢀ
3
ꢀ1
as reported below.

678
G.J. Depree et al. / Journal of Organometallic Chemistry 691 (2006) 667–679
3
ꢀ1
crystals from CHCl /pentane, size 0.72 · 0.40 · 0.28 mm ,
0.104 mm , yellow crystals from CH Cl /petroleum spirit,
2 2
3
3
F(000) = 1312, T = 159 K. Total data 7748, unique data
size 0.20 · 0.16 · 0.08 mm , F(000) = 632, T = 138 K.
Unique data 1873, 4ꢁ < 2h < 45ꢁ, R = 0.0758, [482 data
4
912, (Rint 0.0013), 4ꢁ < 2h < 50ꢁ.
1
ꢀ
3
˚
The structure was crystallographically complex. It was
initially solved in space group P2 /a, although it was
apparent there were numerous significant violations of
the extinctions associated with the a-glide plane. This par-
tial solution led to an R value of 0.28 for 2626 low angle
data with |F | > 4r|F |, but could not be further developed.
with I > 3r(I)], residual De 6 |0.39| e A .The structure
was solved by direct methods and developed and refined
routinely using the SHELX programmes with hydrogen
atoms included in calculated positions, except for the
hydroxyl hydrogen which was fixed in the position located
in a penultimate difference map.
1
1
o
o
The data could also be indexed in an orthorhombic lattice,
but systematic absences (weaknesses) did not correspond to
any known space group. Twinning was suspected, by which
reflections hkl and ꢀhkh + l were overlapped, as a conse-
quence of the relationship 2a*cosb* = c*. With the addi-
tion of one parameter, a, describing the twinning and
4.3. The allyl-cyclopentadiene complex 8
Crystal data: C H NO Mn, M 389.28, monoclinic,
2
0
16
4
r
˚
˚
space group P2 /n, a = 12.109(2) A, b = 8.443(2) A, c =
1
3
˚
˚
17.227(3) A, b = 97.66(3)ꢁ, V = 1745.6(6) A , D = 1.48
calc
2
2 2
ꢀ3
ꢀ1
upon minimising the function R
w
(|F | ꢀ |F | ) ,
g cm , Z = 4, l(Mo Ka) = 0.781 mm , yellow crystals
from CH Cl /petroleum spirit, size 0.62 · 0.50 · 0.24
h k l h k l
o
c
2
2
2
where |F | = a|F | ꢀ (1 ꢀ a)|F
| , the value of R
1
c
h k l
ꢀh k h + l
2
2
3
dropped to 0.18. With the inclusion of most of the missing
atoms, the value dropped to 0.11. However, one of the two
crystallographically independent molecules was transla-
tionally disordered. The constraint of an a-glide plane
was dropped, leading to four crystallographically indepen-
mm , F(000) = 800, T = 130 K. T
0.790, 0.618.
max, min
Unique data 3075, 4ꢁ < 2h < 50ꢁ, R = 0.0594 [I > 3r(I)],
1
ꢀ
3
˚
wR = 0.1539 (all data), residual De 6 |0.96| e A . The
2
structure was solved and refined routinely.
dent molecules in space group P2 (non-standard setting x,
5. Supplementary material
1
y, z and 1/2 ꢀ x, 1/2 + y, ꢀz), where one pair of molecules
0
00
(
the sets headed by Mn and Mn ) was very closely related
Full details of the structure determinations have been
deposited with the Cambridge Crystallographic Data Centre
as CCDC 282598-282600 for 5b, 6a and 8, respectively. Cop-
ies of this information may be obtained free of charge from
The Director, CCDC, 12 Union Road, Cambridge, CB2
1EZ, UK, fax: +44 1223 366 033, e-mail: deposit@ccdc.ac.
uk or on the web www: http://www.ccdc.cam.ac.uk.
by a pseudo a-glide, while the second pair of molecules
formerly disordered) now were ordered in well separated
(
sites (the sets of atoms headed by Mn and Mn*). On fur-
ther refinement the value of R dropped to 0.048. About
1
eight missing hydrogen atoms were readily apparent in a
difference Fourier map (calculated from data de-twinned
using the current value of a). The penultimate R value
1
for a model with only the Mn and carbonyl oxygen atoms
anisotropic was 0.036. In breaking the pseudosymmetry,
Acknowledgements
and in space group P2 with unequal twin components,
We thank Professor Ward Robinson and Dr. Jan Wika-
ira, University of Canterbury, for collection of X-ray inten-
sity data.
1
there are several possible relative orientations of the four
independent molecules. The combination originally
selected led to a false minimum; performing an a-glide
operation on each of the non-pseudo-a glide related mole-
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2
o
parameters reported here as final. Final refinements (on F )
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[
[
[
[
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2
0
.1224, respectively, and to a final value for the twinning
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86 and SHELXL-93 [22].
-
4.2. Dimethyl 1-methyl-1-hydroxypyrrolo[1,2a]-indole-2,3-
dicarboxylate (6a)
[
[
[
Only a weakly diffracting crystal was found, so the
structure determination is of low precision, but confirms
the overall geometry. Crystal data: C H NO , M
r
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1
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1
6
15
5
[
[
3
01.29, monoclinic, space group P2 /c, a = 11.400(10)
1
(
˚
˚
˚
A, b = 6.674(5) A, c = 19.960(10) A, b = 108.59(2)ꢁ, V =
1
3
ꢀ3
˚
439.4(18) A , D = 1.39 g cm , Z = 4, l(Mo Ka) =
calc

G.J. Depree et al. / Journal of Organometallic Chemistry 691 (2006) 667–679
679
[
[
12] J.M. Cooney, DPhil thesis, University of Waikato, 1994.
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[
[
134, see also reference [2].
[
16] G. Ferguson, B. Kaitner, W.B. Whalley, D.A. Taylor, J.R. Liddell,
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[21] M. Eitel, U. Pindur, Synthesis (1989) 364.
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[22] G.M. Sheldrick, SHELXS-86, University of Gottingen, 1986;
G.M. Sheldrick, SHELXL-93, University of Gottingen, 1993.