Amplification of chirality by transition metal coordination: Synthesis of chiral allenes and allene manganese complexes of high enantiomeric purity. Synthesis of methyl (R,E)-(-)-(2,4,5-tetradecatrienoate (pheromone of Acanthoscelides obtectus (say))

Article abstract of DOI:10.1016/S0957-4166(98)00023-8

The enhancement of the asymmetry of choreal oiliness by coordination with a transition metal can be turned to account for (easy) resolution of the complexes and therefore the oiliness themselves. This is illustrated here on allene aldehyde complexes of (η

Full text of DOI:10.1016/S0957-4166(98)00023-8

Pergamon
Tetrahedron: Asymmetry 9 (1998) 697–708
Amplification of chirality by transition metal coordination:
synthesis of chiral allenes and allene manganese complexes of
high enantiomeric purity. Synthesis of methyl (R,E)-(−)-(2,4,5-
tetradecatrienoate (pheromone of Acanthoscelides obtectus (say))
∗
Michel Franck-Neumann, Daniel Martina and Denis Neff
Laboratoire de Chimie Organique Synthétique, Associé au CNRS, Institut de Chimie de l’Université Louis Pasteur, 1 rue
Blaise Pascal, F-67008 Strasbourg Cedex, France
Received 22 December 1997; accepted 19 January 1998
Abstract
The enhancement of the asymmetry of chiral allenes by coordination with a transition metal can be turned
to account for (easy) resolution of the complexes and therefore the allenes themselves. This is illustrated here
on allene aldehyde complexes of (η-methylcyclopentadienyl) dicarbonylmanganese, possibly bearing a second
electron withdrawing substituent, and by the synthesis of an optically active alkenylallenic insect pheromone of
high enantiomeric purity. © 1998 Elsevier Science Ltd. All rights reserved.
1. Introduction
Electrophilic allenes have been obtained from the corresponding conjugated alkynes by easy isomer-
1
ization of their (η-methylcyclopentadienyl) dicarbonylmanganese complexes. The synthesis of optically
2
active allenes can take account of the availability of such allene complexes, since their resolution would
lead to allene enantiomers after decomplexation. In this instance, the most interesting functional group for
further synthetic use is probably the formyl group, particularly because the poorly stable allene aldehydes
are greatly stabilized by complexation. The resolution of chiral allene aldehyde complexes was therefore
our main objective.
∗
Corresponding author. Tel.: (33) 3 88 41 68 11; fax: (33) 3 88 60 42 48; e-mail: mfneu@chimie.u-strasbg.fr
0957-4166/98/$19.00 © 1998 Elsevier Science Ltd. All rights reserved.
PII: S0957-4166(98)00023-8

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M. Franck-Neumann et al. / Tetrahedron: Asymmetry 9 (1998) 697–708
2. Results and discussion
Metal–carbonyl complexes of organic ligands bearing an aldehyde function have been resolved to
enantiomers of high enantiomeric purity by use of several chiral auxiliaries. Among them, (S)-(−)-5-(α-
3
phenylethyl) semioxamazides have been successfully applied to the resolution of tricarbonylchromium
4
5
6
complexes of arenes, and tricarbonyliron complexes of dienes or trimethylenemethanic ligands.
The isomerization of manganese complexes of substituted acetylenic aldehydes (R
6= H), performed
as previously described with basic aluminium oxide led to mixtures of endo and exo allene complexes
which were in general, separable by chromatography. We observed, however, that only the minor exo
1
allene aldehyde complexes could be resolved using the semioxamazide reagent, the mixture of syn and
anti diastereomeric semioxamazones not being well separated by chromatography in the endo series.
By reinvestigation of the base catalysed isomerisation of alkyne to allene complexes, we found that
homogeneous basic systems [KOH–MeOH, MeONa–MeOH, or better 1.8-diazabicyclo(5.4.0)undec-7-
ene (DBU) in THF at −40°C] drove the reaction almost exclusively toward exo complexes [2b,c-→3b,c
(Scheme 1)].
Scheme 1.
In this series, the semioxamazones were formed as mixtures of ca 80% separable anti diastereomers 5
and 6 (less polar group) and ca 20% unseparable syn diastereomers 7 (more polar group). After separation
of the anti diastereomers by simple SiO column chromatography, followed by cleavage with pyruvic
2
5,6
acid, the enantiomeric allene aldehyde complexes (+)-3b,c and (−)-3b,c were obtained with greater
than 95% ee, the method working as well in the simple case of 3a (Scheme 2).
1
The enantiomeric excess could be determined directly by H-NMR measurements using the chiral shift
reagent Eu(hfc) (for 3a) or Eu(dcm) , which performed best here (estimated precision better than 5%
7
3
3
for 3b,c).
3
Highly electrophilic 1-2-η -functionalized 1-formyl allene complexes are also available by isomeriza-
tion of manganese complexes. However their analogous resolution is handicapped by haptotropic shifts
8
9
at the stage of the chiral semioxamazones, apparently catalyzed by silica gel. Semioxamazones of 1-2-
3
η -formylallene complexes, bearing another electrophilic group at position 1, are thus partially intercon-
3
verted to 1-2-η -functionalized (E=CO Me, CHO) allene complexes, bearing now the semioxamazone
2
10
group at position 1. On the contrary, if the formyl group is in position 1, with the other functional group
in 3, the semioxamazones are stable, and can be separated by SiO chromatography. This permitted us
2
to achieve the resolution of the 3-methoxycarbonyl 1-formyl allene complex 9 which gave, with S-(−)-
5
-(α-phenylethyl) semioxamazide, two easily separated diastereomeric semioxamazones 11 ([α] +51,
D

M. Franck-Neumann et al. / Tetrahedron: Asymmetry 9 (1998) 697–708
699
Scheme 2.
4
5%) and 12 ([α] −213, 44%). After regeneration of the aldehyde function the enantiomeric complexes
D
(
+)-9 and (−)-9 were obtained in good overall yields (89% and 92%) with at least 95% ee (NMR in the
presence of Eu(hfc) ; [α] +372 and −371). The racemic complex 9 was obtained as a major product by
3
D
8
regioselective oxidation of the diformyl allene complex 8, using Corey’s procedure for the conversion
11
of aldehydes into esters (Scheme 3).
Being stabilized forms of allene aldehydes, the optically active complexes can obviously be used
for the synthesis of other chiral allenes. Two reactions are particularly worth mentioning: the highly
diastereoselective reaction with Grignard or organolithium reagents to give secondary alcohols and the
Horner–Emmons reaction.
The allene aldehyde complexes 3a and 3c reacted for instance nearly quantitatively with methyl-
or butyllithium in THF at −78°C and with methylmagnesium iodide or n-butylmagnesium bromide
1
in ether at −20°C to give secondary alcohols as single diastereomers ( H-NMR: de >97%). The
nucleophilic attack is therefore most probably an exo process (i.e. at the face opposite the metal) with
a highly preferred s-trans conformation for the ‘unsaturated’ aldehyde. In the solid state, this was the
8
observed conformation for both acrolein subunits of the 1,3-diformylallene manganese complex 8. As a
consequence, the formation of unlike diastereomers would be highly favoured ((S)-allene complex-→(R)-
alcohol, (R)-allene complex-→(S)-alcohol). In the optically active series, no racemization was observed
and secondary allenol complexes of high ee were obtained ((+)-3a-→(−)-13, quant.; (−)-3a-→(+)-14,
9
0%). The enantiomeric excess could easily be determined by use of the shift reagent Eu(hfc) which
3
gave particularly well-split signals with the racemic allenol complexes (ee >97% for (−)-13 and ≥90%
(+)-14; Scheme 4).
The Horner–Emmons reaction allowed a rapid synthesis of the relatively labile sex pheromone of the
male dried bean beetle (Acanthoscelides obtectus (Say))12 obtained as the natural enantiomer with a high
enantiomeric excess (Scheme 5). The formylallene complex (−)-3c was converted by Horner–Emmons

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M. Franck-Neumann et al. / Tetrahedron: Asymmetry 9 (1998) 697–708
Scheme 3.
Scheme 4.
1
reaction into the vinylogous E-ester (−)-15 [79%, [α] =−329, ee 95ꢀ5% ( H-NMR in the presence
D
of Eu(dcm) )] obtained along with 15% separable Z-ester 16. Decomplexation with anhydrous FeCl
3
3
or meta-chloroperbenzoic acid (mCPBA) led to the free allenic pheromone (−)-17 (85%, [α] =−158;
D
Scheme 5). Similarly the non-natural enantiomer (+)-17 of the pheromone ([α] =+158) was obtained
D
from the formylallene complex (+)-3c.
13,14
The absolute configuration of (−)-17 must be R,
so that the configuration of the formyl bearing
carbon of the complex (−)-3c and, most probably, (−)-3b and (−)-3a must be S. The enantiomeric
excess ([α] =−158) is very high in comparison with the natural pheromone ([α] =−128), probably
D
D
13
90% based on the value given by Mori et al. for their synthetic pheromone (ee 92%, [α] =−162).
D

M. Franck-Neumann et al. / Tetrahedron: Asymmetry 9 (1998) 697–708
701
Scheme 5.
Our synthesis compares favourably with other more tedious syntheses of this optically active allenic
pheromone (estimated ee values ranging from 45 to 55%).14,15 In particular, it is noteworthy that the
analogous synthesis of Oehlschalger et al., also using a Horner–Emmons reaction as the last step but
with the poorly stable free aldehyde (41% yield), led to a partially racemized product ([α] =−79.5),
D
although the precursors of the aldehyde were of high enantiomeric purity.15
The advantage of using such manganese complexes for the synthesis of allenes is therefore obvious.
Not only are reactive allenes highly stabilized by coordination with the metal, but in addition, their
efficient resolution is made much easier. Another advantage with chiral allenes is that their enantiomeric
excess can, in general, be easily determined at the stage of their metal complexes by simple NMR
methods based on optically active shift reagents.16
3. Experimental section
Elemental analyses were performed by the Service de Microanalyse du Centre de Recherche Chimie
−1
de l’ULP de Strasbourg. IR spectra were recorded on a Perkin–Elmer IR-177 instrument (ν in cm ).
Optical rotations were determined at 22°C on a Perkin–Elmer 241 MC polarimeter at the sodium D
1
line, concentrations are given in g/100 ml. H NMR (200 MHz) spectra were recorded on a Bruker WP-
2
00 SY spectrometer [δ in ppm referenced to CHCl (7.27 ppm) as an internal standard with chemical
3
shifts referenced to TMS. Coupling constants J are given in hertz; multiplicities are designated as singlet
s), doublet (d), triplet (t), quartet (q) and multiplet (m)]. The solutions were filtered on Millipore
(
membranes (GS 0.22 µm) and degassed with argon before measurement. Melting points were determined
on a Reichert melting point apparatus and are uncorrected. Analytical thin layer chromatography was
performed on Merck Kieselgel 60 F254 glass plates (0.25 mm), compounds were detected by UV light
(
254 nm) and by aspersion with an ethanol–vanilline–H SO solution followed by heating. Column
2 4
chromatography was carried out on Merck Kieselgel 60 (70–230 mesh ASTM). Photolyses were carried
out with a Philips HPK-125 medium pressure Hg lamp in a Pyrex glass reactor.
All reactions were performed under an argon atmosphere in dried glassware. Solvents were distilled
before use: ether and THF over sodium–benzophenone, benzene over sodium and CH Cl over P O .
2
2
2
5
Methyllithium was purchased from Aldrich and titrated with diphenylacetic acid before use.

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M. Franck-Neumann et al. / Tetrahedron: Asymmetry 9 (1998) 697–708
3.1. Preparation of the racemic allene aldehyde complexes 3a–c and 4b,c
The intermediate manganese complexes 2a–c of the acetylenic aldehydes can be isolated, but this was
not necessary for the synthesis of the isomeric allene aldehyde complexes.
3
.2. Preparation of racemic (2-3-η-buta-2,3-dien-1-al) (η-methylcyclopentadienyl) dicarbonylman-
ganese 3a (isomerization with Al O )
2
3
Methylcyclopentadienyl tricarbonylmanganese (2.00 g, 9.17 mmol) was irradiated in anhydrous THF
(
200 ml) at −30°C until one equivalent CO was evolved (ca 40 min). Argon was then bubbled through
the red solution while warming up to 20°C. Tetrolaldehyde (1.00 g, 15 mmol) was added, the UV source
cut off and the mixture was stirred for 4 h. The solution was concentrated to 50 ml in vacuo (15 torr,
2
5°C), added to a suspension of basic Al O (100 g, aluminium oxide 90 active basic Merck no 1076)
2 3
in hexane (100 ml) and stirred for 2 h at 20°C. The mixture was filtered and the Al O was washed with
2
3
CH Cl :MeOH (4:1, 3×150 ml). The combined filtrates were evaporated and the crude complex purified
2
2
by chromatography on a SiO column (150 g, hexane with 20% CH Cl and 10% ether): 1.70 g complex
2
2
2
3
a (72%) was obtained.
1
3a: yellow oil. IR (CCl ): ν=1995, 1935 (C^O), 1665 (C_O). H-NMR (CDCl ): δ=1.90 (s, 3H),
4
3
2.90 (dt, 1H, J=7.5 and 3.0), 4.58 (m, 2H), 4.73 (m, 2H), 5.98 (t, 1H endo, J=3.0), 6.55 (t, 1H exo, J=3.0),
7
.97 (d, 1H, J=7.5). Anal. Calcd for C H MnO (258.16): C, 55.83; H, 4.29. Found: C, 56.09; H, 4.40.
12
11
3
3
.3. Preparation of racemic (2-3-η-deca-2,3-dien-1-al) (η-methylcyclopentadienyl) dicarbonylman-
ganese 3b (exo) and 4b (endo) (isomerization with Al O )
2
3
The same procedure starting from 1.40 g (6.4 mmol) methylcyclopentadienyl tricarbonylmanganese
and 1.14 g (7.5 mmol) 2-n-decynal yielded, after stirring for 12 h at 20°C followed by chromatography
on SiO (150 g, hexane with 15% ether), yielded the exo complex 3b (less polar, 0.58 g, 26.5%) and the
2
endo complex 4b (more polar, 0.73 g, 33.5%).
1
3
b: yellow oil. IR (CCl ): ν=1995, 1940 (C^O), 1670 (C_O). H-NMR (C D ): δ=0.91 (t, 3H, J=6.5),
4
6
6
1
.00–1.49 (mm, 8H), 1.38 (s, 3H), 2.31 (m, 2H), 2.84 (m, 1H), 3.70 (m, 2H), 3.87 (m, 2H), 6.03 (td, 1H
endo, J=7.0 and 2.5), 8.26 (d, 1H, J=7.0). Anal. Calcd for C H MnO (342.32): C, 63.16; H, 6.77.
18
23
3
Found: C, 63.33; H, 7.01.
b: yellow oil. Same IR and nearly the same H-NMR with the exception of the signal of the exo H:
δ=6.76 (td, J=7.0 and 2.5).
1
4
3.4. Isomerization with DBU
The crude THF solution resulting from the irradiation of methylcyclopentadienyl tricarbonylman-
ganese (1.40 g, 6.4 mmol) and 2-n-decynal (1.14 g, 7.5 mmol) was cooled to −40°C. DBU (1.98 g,
1
3 mmol) was added and stirring was continued for 4 h at −40°C. The mixture was poured into aqueous
HCl (100 ml, 1.5 N) and extracted with ether. The organic extracts were washed with saturated brine and
dried with MgSO . After evaporation of the solvents, the complexes were isolated by chromatography
4
on SiO (150 g, hexane with 25% ether). A 1.10 g mixture of the exo and endo complexes 3b and 4b
2
(97:3) was obtained (50% overall yield based on methylcyclopentadienyl tricarbonylmanganese). By a
second careful chromatography on SiO (150 g, hexane with 15% ether), the less polar exo complex 3b
2
was completely freed from the more polar endo complex 4b.

M. Franck-Neumann et al. / Tetrahedron: Asymmetry 9 (1998) 697–708
703
The same isomerization gave a ratio of 95:5 exo:endo complex when performed at +20°C.
3
.5. Preparation of racemic exo-(2-3-η-dodeca-2,3-dien-1-al) (η-methylcyclopentadienyl) dicarbonyl-
manganese 3c (isomerization with DBU)
The same procedure from methylcyclopentadienyl tricarbonylmanganese (1.40 g, 6.4 mmol) and 2-n-
dodecynal (1.35 g, 7.5 mmol) yielded the exo complex 3c (1.16 g, 49%) and the endo complex 4c (0.04
g, 1.7%) slightly contaminated by 3c.
1
3
c: yellow oil. IR (CCl ): ν=1995, 1940 (C^O), 1670 (C_O). H-NMR (C D ): δ=0.89 (t, 3H, J=6.5),
4
6
6
1
.24–1.43 (m, 12H), 1.38 (s, 3H), 2.31 (m, 2H), 2.83 (m, 1H), 3.70 (m, 2H), 3.87 (m, 2H), 6.04 (td, 1H,
J=7.0 and 2.5), 8.25 (d, 1H, J=7.0). Anal. Calcd for C H MnO (370.37): C, 64.86; H, 7.35. Found: C,
20
27
3
65.10; H, 7.49.
3.6. Preparation of the chiral anti-semioxamazones (+)-5a, (−)-5b, (−)-5c, (−)-6a, (+)-6b and (+)-6c
The allene aldehyde complex 3a (1.03 g, 4 mmol), 3b (1.37 g, 4 mmol) or 3c (1.48 g, 4 mmol) and
3
(
S)-(−)-(α-phenylethyl)-5-semioxamazide (0.83 g, 4 mmol) were dissolved with pTsOH (0.02 g, cat.)
in CH Cl (80 ml). After ∼1 h reflux, the starting complex had disappeared (TLC). The solution was
2
2
washed with H O and dried with MgSO . Evaporation of the solvent afforded nearly quantitatively the
2
4
crude semioxamazone mixtures (+)-5a, (−)-6a and 7a (1.79 g); (−)-5b, (+)-6b and 7b (2.12 g); (−)-
5
c, (+)-6c and 7c (2.23 g) respectively. By column chromatography on SiO (150 g, hexane with 35%
2
CH Cl and 5% ether) the crystalline anti semioxamazones were obtained as pure diastereomers, along
2
2
with unseparable mixtures of the pairs of distinctly more polar syn semioxamazones (total yield ca 90%):
+)-5a (less polar, 0.687 g, 38%), (−)-6a (more polar, 0.626 g, 35%), 7a (unseparated mixture, 0.253
g, 14%); (−)-5b (less polar, 0.797 g, 37%), (+)-6b (more polar, 0.679 g, 32%), 7b (unseparated mixture,
(
0
.420 g, 20%); (−)-5c (less polar, 0.836 g, 37%), (+)-6c (more polar, 0.699 g, 31%), 7c (unseparated
mixture, 0.489 g, 22%).
Semioxamazone (+)-5a: yellow crystals, dec. >94°C. [α] =+63 (c=0.4, CHCl ). IR (CHCl ): ν=3380,
D
3
3
1
3
3
300 (NH), 1980, 1925 (C^O), 1670 (C_O, C_N). H-NMR (CDCl ): δ=1.56 (d, 3H, J=7.0), 1.84 (s,
3
H), 3.48 (m, 1H), 4.52 (m, 2H), 4.68 (m, 2H), 5.06 (m, 1H), 5.85 (m, 1H), 6.43 (m, 1H), 6.53 (d, 1H,
J=9.0), 7.26–7.32 (m, 5H), 7.76 (broad d, 1H, J=8.0), 9.70 (s, 1H). Anal. Calcd for C H MnN O
4
22
22
3
(
447.38): C, 59.07; H, 4.96. Found: C, 59.28; H, 5.23.
1
Semioxamazone (−)-6a: yellow crystals, dec. >90°C. [α] =−260 (c=0.4, CHCl ). IR and H-NMR
D
3
very similar to (+)-5a. Anal. for C H MnN O . Found: C, 58.84; H, 4.75.
22
22
3
4
Semioxamazone (−)-5b: yellow crystals, dec. >64°C. [α] =−339 (c=0.6, CHCl ). IR (CHCl ):
D
3
3
1
ν=3380, 3300 (NH), 1985, 1930 (C^O), 1675 (C_O, C_N). H-NMR (C D ): δ=0.91 (t, 3H, J=6.5),
6
6
1
.08 (d, 3H, J=7.0), 1.10–1.60 (m, 8H), 1.30 (s, 3H), 2.36 (m, 2H), 3.34 (m, 1H), 3.76 (m, 1H), 3.83
m, 1H), 3.96 (m, 1H), 4.03 (m, 1H), 5.03 (m, 1H), 6.00 (td, 1H, J=7.0 and 2.5), 6.12 (d, 1H, J=9.0),
.03–7.11 (m, 5H), 7.88 (broad d, 1H, J=8.0), 10.20 (broad s, 1H). Anal. Calcd for C H MnN O
(
7
28
34
3
4
(
489.52): C, 68.70; H, 7.00. Found: C, 68.93; H, 7.21.
Semioxamazone (+)-6b: yellow crystals, dec. >58°C. [α] =+140 (c=0.45, CHCl ). IR and H-NMR
1
D
3
very similar to (−)-5b. Anal. for C H MnN O . Found: C, 68.75; H, 7.09.
2
8
34
3
4
Semioxamazone (−)-5c: yellow crystals, dec. >60°C. [α] =−316 (c=0.7, CHCl ). IR (CHCl ):
D
3
3
1
ν=3380, 3300 (NH), 1980, 1930 (C^O), 1675 (C_O, C_N). H-NMR (C D ): δ=0.92 (t, 3H, J=6.5),
6
6
1
.05 (d, 3H, J=7.0), 1.20–1.55 (m, 15H), 2.35 (m, 2H), 3.32 (m, 1H), 3.73 (m, 1H), 3.80 (m, 1H),
.93 (m, 1H), 3.97 (m, 1H), 5.02 (m, 1H), 5.97–6.05 (m, 2H), 7.02–7.12 (m, 5H), 7.78 (d, 1H, J=9.0),
3

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M. Franck-Neumann et al. / Tetrahedron: Asymmetry 9 (1998) 697–708
1
0.07 (s, 1H). Anal. Calcd for C H MnN O (559.59): C, 64.39; H, 6.84. Found: C, 64.11; H, 6.92.
30 38 3 4
1
Semioxamazone (+)-6c: yellow crystals, dec. >58°C. [α] =+113 (c=0.25, CHCl ). IR and H-NMR very
D
3
similar to (−)-5c. Anal. for C H MnN O . Found: C, 64.77; H, 6.78.
28
34
3
4
3
.7. Regeneration of the formyl group: optically active allene aldehyde complexes (+)-3a, (−)-3a, (−)-
3b, (+)-3b, (−)-3c and (+)-3c
Pyruvic acid (0.25 g, 2.8 mmol) and H O (2 ml) were successively added to a solution of the
2
semioxamazone (0.8 mmol) in acetic acid (25 ml). After stirring for 12 h at rt, H O (80 ml) was added and
2
the mixture was extracted with pentane (3×20 ml). The organic phase was washed with H O, neutralized
2
with a saturated NaHCO solution and dried with MgSO . After evaporation of the solvent, the crude
3
4
complex was filtered on SiO (30 g, hexane with 10% ether).
2
3.8. (+)-exo-(2,3-η-Buta-2,3-dien-1-al) (η-methylcyclopentadienyl) dicarbonylmanganese (+)-3a and
its enantiomer (−)-3a
From the semioxamazones (+)-5a (less polar diastereomer, 0.358 g) and (−)-6a (more polar diastere-
omer, 0.358 g), the aldehydes (+)-3a [0.201 g, 97%, [α] =+560 (c=0.4, CHCl )], and (−)-3a [0.197 g,
D
3
9
5% [α] =−503 (c=0.35, CHCl )] respectively, were obtained. In this case the extraction was carried out
D
3
with ether instead of pentane, and the eluent for the final chromatography was hexane with 20% CH Cl
and 10% ether. The enantiomeric excess was determined by H-NMR in the presence of Eu(hfc) with a
2
2
1
3
molar ratio of shift reagent:complex=6:10. The aldehyde complex (+)-3a showed an ee >97%, while the
ee of (−)-3a was only 90%, the more polar semioxamazone (−)-6a being slightly contaminated by the
other diastereomer.
3
.9. (2S)-(−)-exo-(2,3-η-Deca-2,3-dien-1-al) (η-methylcyclopentadienyl) dicarbonylmanganese (−)-
3b and its enantiomer (2R)-(+)-3b
From the semioxamazone (−)-5b (less polar diastereomer, 0.425 g) and (+)-6b (more polar diastere-
omer, 0.425 g), the aldehydes (−)-3b [0.268, 98%, [α] =−602 (c=0.45, CHCl )] and (+)-3b [0.266 g,
D
3
1
9
7%, [α] =+595 (c=0.45, CHCl )] respectively, were obtained. The enantiomeric excess ( H-NMR in
the presence of 0.2 molar equivalents of Eu(dcm) was >95%, no trace of the other enantiomer being
D
3
3
observed.
3
.10. (2S)-(−)-exo-(2,3-η-Dodeca-2,3-dien-1-al) (η-methylcyclopentadienyl) dicarbonylmanganese
(−)-3c and its enantiomer (2R)-(+)-3c
From the semioxamazones (−)-5c (less polar diastereomer, 0.445 g) and (+)-6c (more polar diastere-
omer, 0.445 g), the aldehydes (−)-3 (0.290 g, 98%, [α] =−549 (c=0.4, CHCl )] and (+)-3c [0.292 g,
D
3
9
9% [α] =+526 (c=0.4, CHCl )] respectively, were obtained. The enantiomeric excess was determined
D
3
as for 3b and was also >95%.

M. Franck-Neumann et al. / Tetrahedron: Asymmetry 9 (1998) 697–708
705
3
.11. Racemic
exo-(2,3-η-4-methoxycarbonyl-buta-2,3-dien-1-al)
(η-methylcyclopentadienyl)
dicarbonylmanganese 9 and diester 10
8
The 1,3-diformylallene complex 8 (0.48 g, 1.7 mmol) in MeOH (30 ml) was added at 0°C to a
suspension of MnO (3.45 g, 40 mmol, manganese(IV) oxide precipitated active Merck no. 805958)
2
in a solution of KCN (0.65 g, 10 mmol) in acetic acid (0.18 g) and MeOH (35 ml). After stirring 2 h
at 0°C and filtration, water (60 ml) was added and the mixture was extracted with CH Cl (2×50 ml).
2
2
The organic phase was dried with MgSO . Evaporation of the solvent and chromatography on SiO (60
4
2
g, hexane with 35% CH Cl and 5% ether) afforded the aldehyde–ester complex 9 (more polar, 0.380 g,
2
2
7
0%) and the diester complex 10 (less polar, 0.114 g, 19%).
1
9
: yellow oil. IR (CCl ): ν=2005, 1960 (C^O), 1700, 1680 (C_O). H-NMR (CDCl ): δ=1.92 (s,
4
3
3H), 3.26 (dd, 1H, J=7.0 and 2.5), 3.72 (s, 3H), 4.65 (m, 2H), 4.78 (m, 2H), 6.58 (d, 1H, J=2.5), 8.10 (d,
H, J=7.0). Anal. Calcd for C H MnO (316.19): C, 53.18; H, 4.14. Found: C, 53.40; H, 4.32.
1
14
13
5
3.12. Semioxamazones (+)-11 and (−)-12
To a solution of the complex 9 (0.245 g, 0.78 mmol) in CH Cl (10 ml) were added at 0°C (S)-
2
2
(
−)-(α-phenylethyl)-5-semioxamazide (0.165 g, 0.8 mmol) and p-TsOH (0.01 g, cat). After stirring
for 10 min at 0°C, water (10 ml) was added and the mixture was extracted with CH Cl (20 ml).
2
2
The organic phase was dried with MgSO and the solvent was evaporated. The crude mixture (0.395
4
g) was chromatographed on SiO (100 g, CH Cl with 25% hexane and 10% ether). This afforded the
2
2
2
diastereomeric semioxamazones (+)-11 (less polar, 0.175 g, 45%) and (−)-12 (more polar, 0.172 g, 44%).
Semioxamazone (+)-11: yellow crystals, mp 168–170°C. [α] =+51 (c=0.25, CHCl ). IR (CHCl ):
D
3
3
1
ν=3380, 3300 (NH), 2000, 1940 (C^O), 1700 (C_O, ester), 1675 (C_O, C_N). H-NMR (CDCl ):
3
δ=1.57 (d, 3H, J=7.O), 1.88 (s, 3H), 3.71 (s, 3H), 3.92 (dd, 1H, J=9.0 and 2.0), 4.56 (m, 1H), 4.63 (m,
1
H), 4.75 (m, 2H), 5.09 (m, 1H), 6.52 (d, 1H, J=2.0), 6.58 (d, 1H, J=9.0), 7.20–7.45 (m, 5H), 7.75 (broad
d, 1H, J=7.5), 10.02 (s, 1H). Anal. Calcd for C H MnO (463.39): C, 62.21; H, 5.22. Found: C, 62.34;
24
24
6
H, 5.36.
1
Semioxamazone (−)-12: yellow crystals, mp 169–170°C. [α] =−213 (c=0.25, CHCl ). IR and H-
D
3
NMR very similar to (−)-12. Anal. for C H MnO . Found: C, 62.50; H, 5.43.
24
24
6
3.13. Regeneration of the formyl group: optically active allene aldehyde ester complexes (+)-9 and (−)-9
To a solution of the semioxamazone (+)-11 (0.140 g, 0.28 mmol) in acetic acid (5 ml) were successively
added pyruvic acid (0.10 ml, 1.2 mmol) and H O (0.5 ml). After stirring for 3 h at rt, water (10 ml) was
2
added and the mixture was extracted with ether (3×10 ml). The organic phase was washed with H O,
2
then with saturated brine and dried with MgSO . Evaporation of the solvent and chromatography on
4
SiO (10 g, CH Cl with 30% hexane and 5% ether) yielded (+)-9 [0.078 g, 89%, [α] =+372 (c=1.5,
2
2
2
D
CHCl )].
3
Similarly, from the semioxamazone (−)-12 (0.150 g, 0.3 mmol), the enantiomeric complex (−)-9 was
obtained [0.087 g, 92%, [α] =−371 (c=1.1, CHCl )].
D
3
1
The optical purity of (+)-9 and (−)-9, determined by H-NMR in the presence of Eu(hfc) , was
3
estimated to be >90% (no trace of the other enantiomer was detected, ee=95ꢀ5%, limit of precision
of the method in this case).

706
M. Franck-Neumann et al. / Tetrahedron: Asymmetry 9 (1998) 697–708
3.14. Reaction of allene aldehyde complexes with organometallics: synthesis of the secondary alcohols
(−)-13 and (+)-14
3
(
.14.1. Addition of methyllithium to (+)-3a
−)-exo-(2-3-η-Penta-1,2-dien-4-ol) (η-methylcyclopentadienyl)
Methyllithium (0.66 ml, sol 1.67 M in ether, 1.1 mmol) was added dropwise at −78°C to (+)-3a
dicarbonylmanganese
(−)-13
(
0.240 g, 0.93 mmol, ee >97%) in THF (10 ml). After stirring for 15 min at −78°C, a saturated solution
of NH Cl (10 ml) was added and the mixture was extracted with ether (2×20 ml). The organic phase
4
was dried with MgSO , the solvents were evaporated and the residue chromatographed on SiO (20
4
2
g, hexane with 30% ether): (−)-13 (0.250 g, 98%) was obtained as a single diastereomer (NMR, shift
reagents).
(
−)-13: pale yellow oil. [α] =−116 (c=0.3, CHCl ). IR (CHCl ): ν=3600, 3500–3300 (OH), 1965,
D
3
3
1
1
1
905 (C^O). H-NMR (CDCl ): δ=1.29 (d, 3H, J=6.0), 1.89 (s, 3H), 2.13 (broad d, 1H, J=4.0), 2.60 (m,
H), 3.33 (m, 1H), 4.40 (m, 1H), 4.45 (m, 1H), 4.57 (m, 2H), 5.67 (dd, 1H, J=3.0 and 1.0), 6.23 (dd, 1H,
3
J=3.0 and 1.0). Anal. Calcd for C H MnO (274.20): C, 56.95; H, 5.51. Found: C, 57.26; H, 5.69.
13
15
3
3
.14.2. Addition of n-butylmagnesium bromide to (−)-3a
(+)-exo-(2-3-η-Octa-1,2-dien-4-ol) (η-methylcyclpentadienyl) dicarbonylmanganese (+)-14 The
complex (−)-3a (0.161 g, 0.62 mmol, ee ∼90%) in THF (10 ml) was added dropwise at −20°C to
n-butylmagnesium bromide prepared in refluxing ether (8 ml, 30 min) from n-butyl bromide (0.135 ml,
1
.25 mmol) and magnesium (0.030 g, 1.25 mmol). After 30 min, a saturated solution of NH Cl (10 ml)
4
was added at −20°C and the mixture was extracted with ether (2×15 ml). The organic phase was washed
with saturated brine, dried with MgSO , the solvents evaporated and the residue chromatographed on
4
SiO (10 g, hexane with 20% ether): (+)-14 (0.117 g, 90%) was obtained as a single diastereomer (NMR,
2
shift reagents).
1
(
+)-14: yellow oil. [α] =+146 (c=0.2, CHCl ). IR (CHCl ): ν=3600 (OH), 1975, 1905 (C^O). H-
D
3
3
NMR (CDCl ): δ=1.02 (t, 3H, J=7.0), 1.45 (m, 4H), 1.59 (s, 3H), 1.70 (m, 2H), 1.88 (broad d, 1H, J=4.5),
3
2.60 (dt, 1H, J=8.0 and 3.0), 3.16 (m, 1H), 3.97 (m, 2H), 4.12 (m, 2H), 5.78 (dd, 1H, J=3.0 and 1.5), 6.37
(
dd, 1H, J=3.0 and 1.5). Anal. Calcd for C H MnO (316.28): C, 60.76; H, 6.69. Found: C, 60.98; H,
16
21
3
6
.87.
1
The enantiomeric excess of (−)-13 and (+)-14 was checked by H-NMR in the presence of Eu(hfc)
3
(
molar ratio of shift reagent:complex ∼4:10). (−)-13 was found to have an ee >97%, but (+)-14 of only
0%. This correlates with the optical purity of the starting complexes (+)-3a and (−)-3a, indicating that
no racemization occurred.
9
3.15. Horner–Emmons olefination
3
.15.1. (4R,E)-(−)-exo-(4-5-η-Methyl-tetradeca-2,4,5-trien-1-oate) (η-methylcyclopentadienyl) dicar-
bonylmanganese (−)-15
Sodium hydride (0.080 g, 3.3 mmol) was added to a solution of methyl dimethylphosphonoacetate
(0.667 g, 3.67 mmol) in dry THF (20 ml). After stirring for 30 min at rt, the mixture was cooled to
−
10°C and the aldehyde complex (−)-3c (1.23 g, 3.3 mmol) in THF (20 ml) was added dropwise. After
stirring for 12 h at rt, H O (20 ml) was added, followed by extraction with ether. The organic phase was
2
washed with a saturated aqueous NaCl solution and dried with MgSO . After evaporation of the solvents
4
and chromatography on SiO (30 g, hexane with 5% ether), the unreacted starting complex (−)-3c (0.125
2
g, 10%), the complexed exo-E-pheromone (−)-15 (1.005 g, 71%) and the relatively labile complexed exo-

M. Franck-Neumann et al. / Tetrahedron: Asymmetry 9 (1998) 697–708
707
Z-derivative 16 (0.195, 14%) were successively obtained. Yields for (−)-15 and 16, based on transformed
complex (−)-3c: 79 and 15%.
(
exo-E-Pheromone) (methylcyclopentadienyl) dicarbonylmanganese (−)-15: orange oil. [α] =−329
D
1
(
(
c=0.25, CHCl ). IR (CCl ): ν=1980, 1935 (C^O), 1705 (C_O), 1595 (C_C). H-NMR (C D ): δ=0.89
t, 3H, J=6.5), 1.28–1.34 (m, 10H), 1.40 (s, 3H), 1.40–1.60 (m, 2H), 2.38 (m, 2H), 2.71 (dd, 1H, J=11.0
3
4
6
6
and 3.0), 3.43 (s, 3H), 3.80 (m, 2H), 3.94 (m, 2H), 5.91 (td, 1H, J=7.0 and 3.0), 6.17 (d, 1H, J=15.0), 6.68
(
dd, 1H, J=15.0 and 11.0). Anal. Calcd for C H MnO (426.44): C, 64.78; H, 7.33. Found: C, 64.41;
23 31 4
H, 7.28.
3.16. Decomplexation: (R)-(−)-pheromone (−)-17
Anhydrous iron trichloride (1.40 g, 8.6 mmol) in ether (20 ml) was slowly added at −20°C to the
complex (−)-15 (0.70 g, 1.64 mmol) in ether (20 ml). The reaction was monitored by TLC. After total
disappearance of the complex, the addition was stopped and H O (20 ml) was added. The aqueous phase
2
was extracted with ether and the combined organic extracts were washed with a saturated NaCl solution
and dried with MgSO . After evaporation of the solvent and chromatography on SiO (30 g, hexane
4
2
with 10% benzene), the pheromone (−)-17 was obtained [0.325 g, 1.38 mmol, 84%, [α] =−158 (c=1.4,
D
2,13
hexane)]. The spectroscopic data were identical with those reported in the literature.1
The decomplexation can also be performed with mCPBA (0.452 g complex (−)-15, 1.06 mmol and
1
.45 g mCPBA of 85% purity, 2 mmol) in CH Cl (30 ml) at −78°C (5 min), the yield being slightly
2
2
17
better (0.213 g (−)-17, 85%).
References
1. Franck-Neumann, M.; Brion, F. Angew. Chem., 1979, 91, 736; Angew. Chem. Int. Ed. Engl., 1979, 18, 688. Exo and endo
refer to the relative positions of the metal and the larger substituent of the uncoordinated double bond.
2
. Rossi, R.; Diversi, P. Synthesis, 1973, 25. For the difficulty in generating the axial chirality of the allenic system in a well
defined manner cf. Morrison, J. D.; Mosher, H. S. In Asymmetric Organic Reactions, Prentice-Hall, Englewood Cliffs, New
Jersey, 1971, pp. 386–397. An important method for the asymmetric synthesis of optically active allenes is by conversion of
1
3–15
centrodissymmetric compounds starting from previously resolved propargylic alcohols or derivatives:
B.; Gore, J. Tetrahedron Lett., 1984, 25, 845. Alexakis, A.; Marek, I.; Mangeney, P.; Normant, J. F. J. Am. Chem. Soc.,
990, 112, 8042 and references therein; Elsevier, C. J.; Vermeer, P. J. Org. Chem., 1989, 54, 3726 and references therein.
Colas, Y.; Cazes,
1
The resolution of chiral allenes, mainly acids, by formation of separable diastereomers, is frequently only partial and critical
in practice. See however the favorable case of pentadienedioic acid: Aso, M.; Ikeda, I.; Kawabe, T.; Shiro, M.; Kanematsu,
K. Tetrahedron Lett., 1992, 33, 5787.
3
4
5
. Leonard, N. J.; Boyer, J. H. J. Org. Chem., 1950, 15, 42.
. Solladié-Cavallo, A.; Tsamo, E.; Solladié, G. J. Org. Chem., 1979, 44, 4189.
. Franck-Neumann, M.; Martina, D.; Heitz, M. P. Tetrahedron Lett., 1982, 23, 3493. Franck-Neumann, M.; Martina, D.;
Heitz, M. P. J. Organomet. Chem., 1986, 301, 61.
6. Franck-Neumann, M.; Martina, D.; Heitz, M. P. Tetrahedron Lett., 1989, 30, 6679.
7. Whitesides, G. M.; Wernick, D. L.; Lewis, D. W.; McCreary, M. D. J. Am. Chem. Soc., 1974, 96, 1038.
8. Franck-Neumann, M.; Neff, D.; Nouali, H.; Martina, D.; De Cian, A. Synlett, 1994, 657.
9. The tendency to undergo such haptotropic shifts has still been noticed for exo complexes of ligands such as 1-
methoxycarbonyl-3-formyl-allene.8
10. The 1,3-diformylallene complex 8 could only be enantiomerically enriched, the semioxamazones being incompletely
separated (a 75:25 fraction of two diastereomeric semioxamazones gave a dialdehyde complex of [α]
1. Corey, E. J.; Gilman, N. W.; Ganem, B. E. J. Am. Chem. Soc., 1968, 90, 5616.
2. Horler, D. F. J. Chem. Soc. (C), 1970, 859.
D
=−483).
1
1
1
3. Mori, K.; Nukada, T.; Ebata, T. Tetrahedron, 1981, 37, 1343.

708
M. Franck-Neumann et al. / Tetrahedron: Asymmetry 9 (1998) 697–708
1
1
1
4. Pirkle, W. H.; Boeder, C. W. J. Org. Chem., 1978, 43, 2091.
5. Oehlschlager, A. C.; Czyzewska, E. Tetrahedron Lett., 1983, 24, 5587.
6. This technique is, in general, not adequate for the assessment of enantiomeric purity of chiral allenes which are not
bonded to metals. An ingenious trick is therefore to use intermediate silver complexes: Mannschreck, A.; Munninger,
W.; Burgemeister, T.; Goré, J.; Cazes, B. Tetrahedron, 1986, 42, 399.
1
3
7. Sensitive allenes such as α-alcohols can be obtained by decomplexation of their manganese complexes with FeCl , however
with partial non-stereospecific formation of α-allenic chlorides. In this case, the decomplexation with mCPBA gives far
better results.