Cross-Metathesis of Bronsted Acid Masked Alkenylamines with Acrylates for the Synthesis of Polyamide Monomers

Article abstract of DOI:10.1021/acs.joc.5b02484

Ruthenium-alkylidene-catalyzed cross-metathesis of a range of homologous alkenylamine salts provides expedient and high-yielding routes to commercially valuable polyamide monomers using a single catalyst, telescopic workup, and mild experimental conditions.

Full text of DOI:10.1021/acs.joc.5b02484

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Article
Cross-metathesis of Brønsted acid-masked alkenyl amines
with acrylates for the synthesis of polyamide monomers
Nicolas Daniel Spiccia, Szabolcs Solyom, Clint Peter Woodward, W. Roy Jackson, and Andrea Jane Robinson
J. Org. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.joc.5b02484 • Publication Date (Web): 22 Jan 2016
Downloaded from http://pubs.acs.org on January 27, 2016
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Cross-metathesis of Brønsted acid-masked alkenyl amines with acrylates for the
synthesis of polyamide monomers
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Nicolas Daniel Spiccia, Szabolcs Solyom, Clint Peter Woodward, William Roy Jackson, Andrea Jane
Robinson*
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School of Chemistry, Monash University, Clayton, Victoria 3800, Australia
Corresponding Author: *Eꢀmail: andrea.robinson@monash.edu
Graphical Abstract
Rutheniumꢀalkylidene catalyzed cross metathesis of a range of homologous alkenylamine salts provides
expedient and high yielding routes to commercially valuable polyamide monomers using a single catalyst,
telescopic workup and mild experimental conditions.
Introduction
Since the early 20th century, polyamides have been used in the production of synthetic resins and fibres for a
variety of applications such as clothing, home wares, electronics and automotive parts.1, 2 Copolymer
polyamides are synthesised by the condensation stepꢀgrowth polymerisation of diamines with dicarboxylic
acids, e.g. PAꢀ6,6, Kevlar®, Nomex® and Stanyl®.3 Homopolymer polyamides are synthesised by the
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condensation stepꢀgrowth polymerisation of amino acids or their derivatives, e.g PAꢀ6 and Rilsan® (PAꢀ
11).4 The traditional production of these monomers relies on the use of chemicals such as acrylonitrile,
carbon monoxide, hydrogen cyanide and high pressurised hydrogen which pose handling risks to
manufacturers and the surrounding environment.3ꢀ6
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In a previous communication we outlined a catalytic synthesis for the production of acyclic unsaturated
diamines 1 using olefin metathesis (Scheme 1).7 In this paper we describe an extension of this work and show
how unsaturated amine salts 2 can be diversionally transformed by cross metathesis with either methyl
acrylate (3) or acrylic acid (4) into unsaturated aminoesters or acids 5. These, or the previously described
diamine salts 1, can be hydrogenated in tandem using the residual ruthenium as catalyst to give saturated
amino esters/acids 6 or diamines 7 for commercial polymer production.
Self-
Metathesis
H2
NH
NH
3.2TfO
3.2TfO
TfO
H3N
H3N
H3N
2
1
7
MesN NMes
Cl2Ru
8
O
O
Cross-
Metathesis
O
H2
H3N
TfO
H3N
TfO
OMe/OH
OMe/OH
O
5
6
OMe
3 (4, Me=H)
Scheme 1. Polyamide monomers
Numerous examples of accessing PA monomers via olefin metathesis have been reported.8 Omegaꢀ
unsaturated fatty acids (and their esters) have been used as starting materials whereupon i) CM with
alkenylnitriles and hydrogenation,9aꢀb ii) conversion to cyanoalkenes10aꢀc or carbamates,11 CM with methyl
acrylate and hydrogenation, iii) CM with allyl chloride and amination,12 iv) ethenolysis, reductive
ozonolysis and reductive amination,13 v) isomerization–methoxycarbonylation–transesterification14
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and vi) amidation with alkenylamines and RCM/hydrogenation15 yields PA monomers, and vii) CM
with methyl acrylate16 yields dicarboxylic acid esters.
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Results and Discussion
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Our previous work showed that selfꢀmetathesis of alkenyl amine salts 2 with ruthenium(I) benzylidene preꢀ
catalyst (8) proceeded in good yield to provide unsaturated diamine salts 1 as illustrated by the reaction of
allylamine triflate (Scheme 1).7, 17 The choice of counterion and solvent was found to be of paramount
importance since they jointly control starting material and product solubility and hence reaction yield.
Towards this end, the most suitable counterions for metathesis reactions with allyl ammonium salts were the
tetrafluoroborate and triflate anions, which also exhibited good solubility in ethyl acetate. The conjugate
acids of each of these anions possess pKa values < 3 in acetonitrile.18aꢀb However, longer chain alkenyl
amines gave excellent conversions when using their cheaper and easier to handle tosylate salts.
The optimised reaction conditions used for tandem self-metathesis have now been applied to the
cross-metathesis of alkenyl ammonium salts with methyl acrylate (3) and acrylic acid (4) (Scheme 1).
Initial studies were carried out using salts of allylamine leading to the formation of unsaturated Nylon-
4 precursors. A large excess of the acrylate (20 eq.) was used to give a high equilibrium yield of the
cross product. The yields were found to be dependent on the anion as per the homodimerization
experiments.7 Near complete conversion of allylammonium salts 2 was obtained for the triflate (TfO-,
>99%) using optimised conditions; slightly lower yields were obtained using tetrafluoroborate salts
-
(BF4 , 81%) and a lower yield still (26%) with the tosylate salt (TsO-). As expected the yields of cross
metathesis products were highly dependant on the molar equivalents of acrylate as shown in Table 1
for reaction of methyl acrylate (3) with allylamine triflate (2).
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Table 1. Reactions of allylamine triflate (2) with differing equivalents of methyl acrylate (3)
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Entry
Eq. of 3
Homodimer 1
Cross
product 5
30%
40%
60%
82%
>95%
(E:Z)a
1
2
3
4
5
1
2
5
10
20
70%
60%
40%
18%
<5%
9:2
9:2
9:2
9:2
9:2
aAs determined by NMR spectroscopy on crude reaction mixtures.
The results show that homodimerisation of the unsaturated ammonium salt 2 competes with crossꢀmetathesis
with 3 to yield 5 and that molar ratios of less than 10:1 (entries 1ꢀ3) gave significant amounts of homodimer
1. Only very small amounts of homodimer were obtained when a 20:1 ratio of methyl acrylate to amine salt 2
was used (entry 5). Conveniently, it was found that the minor homodimer salt could be precipitated from the
reaction mixture by the addition of a small volume of ethyl acetate. This allowed pure target molecule 5 to be
isolated after filtration in all cases.
The reaction time required for complete conversion of 2 to 5 using the 20:1 ratio of reactants was also
investigated and it was found that reaction for two hours was sufficient to give complete conversion. This
reaction time was therefore used in most of the subsequent reactions. Catalyst loading was also investigated
and the result is summarized in Table 2. Near complete conversion was obtained with 1 mol% of catalyst (8)
but the yield decreased when lower catalyst loading, 0.5 mol% and 0.1 mol%, was used. The ratio of
homodimer 1 to cross product 5 also increased as the catalyst loading was reduced.
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Table 2. Effect of catalyst loading on conversion of (2)a,b
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Cross
Product
5
Mol% of catalyst
Conversion
(%)
Homodimer
8
1
0.1
0.5
1
2.5
5
81
89
93
98
97
20
20
9
7
2
61
69
83
91
95
aReactions with methyl acrylate (3): ammonium salt 2, (20:1). Conversion of 2 and product ratios (1 and 5)
b
determined by NMR spectroscopy on crude reaction mixtures.
Recovery and reuse of excess methyl acrylate was investigated using 1 mol% of catalyst. The result in
Table 3 shows that high and consistent conversion to the required cross product 5 can be achieved
using recycled methyl acrylate.
Table 3. Reactions using recovered methyl acrylate (3) and solventa
Homodimer
Cross Product
Cycle no.
Conversion (%)
1
13
8
17
15
5
1
2
3
4
93
87
88
94
78
79
72
79
aReactions with methyl acrylate (3): ammonium salt 2, (20:1).
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The formation of large amounts of the amine homodimer when low ratios of methyl acrylate to ammonium
salts were used was disappointing. Homodimerisation of methyl acrylate (3), an electron poor alkene is
expected to be slow19 and only a small amount of dimethylfumarate or maleate was detected. The formation
of crossꢀproduct 5 can arise either by direct reaction of the methyl acrylate (3) with the ammonium salt 2 or
indirectly by reaction with the homodimer salt 1. Reaction of the crossꢀproduct 5 with the other alkenes
present in the reaction mixture, i.e. itself 5, methyl acrylate (3) or the homodimer 1, would be expected to be
slow and the equilibrium constants for these reactions would be expected to favour the cross product 5.
Reactions were carried out with a 1:1 molar ratio of ammonium salt 2 and crossꢀpartner 3 for 1, 2 and 3 days.
However, the ratio of homodimer salt 1 to crossꢀproduct 5 was found to only slightly increase with increasing
time.20
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Further attempts to overcome the need for a large excess of acrylate involved the slow addition of the
allylamine triflate salt 2 to a solution of the catalyst (8, 5 mol%) and methyl acrylate (3). Significantly, this
approach reduced the ratio of (2):(3) to 1:2. Addition of 2 over one hour resulted in improved conversion to
the target cross product 5: two reactions gave 93 and 89% conversion with homodimer: cross product ratios
of ~1:2. Unfortunately, further experiments with slower addition times of two and four hours, or reactions
with only 1 mol% catalyst, gave less favourable ratios of homodimer 1 and cross product 5. In contrast, a
longer chain analogue, an undecenyl ammonium tosylate salt, reacted well under slow addition conditions:
with two equivalents of methyl acrylate (3) and 1 mol% of catalyst (8), the target cross product was obtained
in 70% isolated yield.
Cross metathesis of the above described C3 allylamine substrate proved to be the most challenging
unsaturated amine we investigated. To expand the scope towards other potentially useful polyamide
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monomers, previously described crossꢀmetathesis conditions were applied to the reaction of higher order
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alkenyl ammonium salts 9 with both methyl acrylate and acrylic acid (Table 4).
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Table 4. Generation of Nylon-4, 5 and -6 precursorsa
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O
O
8 (1 mol%)
EtOAc, ꢀ
X . H3N
+
R2
NH3 . X
n
OR1
3 or 4
OR1
n
9
10
CM
Entry
n
X
R1
R2
Product
(Conv %)b
>99%c
>99%
(E:Z)
1
2
3
4
5
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8
9
2
2
3
3
3
8
8
1
2
3
TfO
BF4
TfO
BF4
TsO
BF4
TsO
TfO
BF4
BF4
Me
Me
Me
Me
Me
Me
Me
H
H
H
H
H
H
Me
Me
H
H
H
6:1
7:1
7:1
10:1
10:1
10:1
20:1
>3:1f
7:1
>95%
>99%
>99%
>99%d
>99%d
>95%
H
H
>99%
10
>99%
>20:1
(70%)e
>99%
11
3
TfO
H
H
>20:1
(95%)e
>99%
12
13
3
8
TsO
TsO
H
H
H
Me
>20:1
>20:1
>99f
aReactions with methyl acrylate (3) or acrylic acid (4): ammonium salt 9, (20:1), catalyst (8, 1 mol%),
b
c
EtOAc, ꢁ, 1 hr. As determined by NMR spectroscopy on crude reaction mixtures. Reaction performed as
for (a) using 5 mol% of catalyst (8). Isomerisation products (minor) detected by ESI+ mass spectrometry.
d
eIsolated yield by precipitation (in parenthesis).
1
All of the reactions gave >95% conversion to 10. HꢀNMR spectroscopy of the total reaction products are
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shown in the appendix and only a trace of homodimer or unreacted unsaturated amine salts can be seen.
Reactions of methyl acrylate with butenylamine (entries 1 and 2) and pentenylamine salts (entries 3ꢀ5) all
gave clean conversion to the desired cross products 10 (n=2 and 3) respectively; reaction at gram scale under
identical conditions also gave quantitative yield of the target cross product. Increase in chain length (n=8) led
to even smaller traces of homodimeric product probably due to steric reasons (entries 6 and 7). Once again
excellent ratios of E:Z were observed with increasing chain length. Reaction of the undecꢀ2ꢀenylamine
tetrafluoroboric acid salt (entry 6) gave complete conversion but ESI mass spectrometry showed evidence of
shorter chain analogues arising from double bond isomerisation prior to cross metathesis. Reaction of the
unsaturated amine salts with acrylic acid (entries 8ꢀ13) also gave excellent results. Recovery and reuse of the
acrylic acid involved distillation of the unreacted acid at 60 ᵒC/40 mmHg. The recovered acid from a reaction
of 4ꢀpentenylammonium triflate under the same conditions as described in Table 4 (entry 13) again gave
>99% conversion to the cross product with only a trace of homodimer. Reaction of the tosylate salt of undecꢀ
2ꢀenylamine with acrylic acid using 5 mol% catalyst also gave the cross product in excellent conversion
without byproducts arising from isomerisation. Slow addition of 4ꢀpentenylammonium triflate (over 1 hour)
to a solution of acrylic acid and HG 2nd catalyst (8) was also investigated. Using a 2:1 ratio of amine salt to
acrylic acid gave complete conversion to almost pure cross product (<5% homodimer) when the tosylate salt
was used. A similar result was obtained for a reaction of the undecenylamine tosylate even when using only
1% catalyst loading.
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In order to produce monomers suitable for established commercial condensation polyamides, e.g. PAꢀ6,6, the
introduced C=C bond needs to be reduced. The tandem metathesis/hydrogenation of both the homodimers
(e.g. 1) and the crossꢀmetathesis products (e.g. 5) was therefore investigated (Tables 5 and 6). It has
previously been shown residual ruthenium from the metathesis reaction can be used as the catalyst for
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subsequent hydrogenation reactions under mild experimental conditions.21aꢀb, 22aꢀ22i
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Table 5. Tandem cross metathesis/hydrogenation route to diamine salts 1a
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Isolated
Yield
Entry
Substrate
Product
1
2
3
4
91%
>99%
90%
>99%
aReaction conditions: i) Metathesis: Amine, catalyst (8, 5 mol%), EtOAc, ꢁ, 16 hrs, followed by ii)
Hydrogenation: Reaction mixture from i), MeOH, H2 (60 psi), room temperature, 16 hrs.
Selfꢀmetathesis of allylammonium triflate and tetrafluoroborate salts followed by tandem hydrogenation gave
the desired saturated diammonium salts in excellent yield (91% and >99% respectively) after precipitation
(Table 5, entries 1 and 2). Tandem selfꢀmetathesis/hydrogenation of 3ꢀbutenylammonium tosylate gave the
saturated diammonium salt, which is a protonated form of the useful PAꢀ6,6 monomer hexamethylene
diamine, in excellent isolated yield 90% (entry 3). No homologues were detected by mass spectrometry,
indicating that the mild conditions prevent concomitant isomerisation during the metathesis step. The long
chain undecꢀ9ꢀenylamine tosylate also gave the saturated long chained diammonium salt in excellent yield
(>99%) (entry 4).
Tandem hydrogenation was then attempted with the intention of generating saturated amino ester salts
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suitable for synthesis of saturated Nylon precursors (Table 6). Unsurprisingly, the amino acrylate products
were more difficult to hydrogenate than the unsaturated diamines, where previously established conditions
(60 psi H2, room temperature) failed to yield any of the desired saturated amino esters. Fortunately,
quantitative conversion to the saturated amino ester salts was obtained when a higher pressure of hydrogen
(90 psi) and elevated temperature (60 °C) were employed in the presence of the residual Ruꢀresidue from the
metathesis reaction. Using this two stepꢀtandem approach, C4, C5 and C6 amino ester salts (Table 6, entries
1ꢀ3) and Nylon 6 amino acid monomer (entry 4), all suitable for homopolymer polyamide synthesis, were
prepared in excellent conversion.
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Table 6. Metathesis/hydrogenation route to Nylon 4, 5 and 6 monomersa
1. 8 (5 mol%), EtOAc, ꢀ
2. 90 psi H2, MeOH, 60oC
O
O
X . H3N
NH2 . X
n
+
OR
OR
n
3 or 4
Entry
n
X
R
CM/H2 Product
(Conv %)b
>99%
1
2
3
4
1
2
3
3
TfO
BF4
BF4
BF4
Me
Me
Me
H
>99%
95%c
97%d
aReactions with methyl acrylate (3) or acrylic acid (4): ammonium salt 9, (20:1), catalyst (8, 5 mol%),
EtOAc, ꢁ, 16ꢀ24 hrs, followed by solvent exchange to MeOH, H2 (90 psi), 60 °C, 16 hrs. bAs determined by
c
d
NMR spectroscopy on reaction mixtures. Dimethyl succinate present in crude reaction product. Cross
metathesis reaction (1 hr); Transesterification (10%) to the methyl ester was also observed in the crude
reaction product. Product characterised via esterification.
Conclusion
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Ruthenium catalysed cross metathesis of alkenylamine salts with an excess of methyl acrylate or acrylic acid
gives excellent yields of unsaturated aminoacids or aminoesters. The excess methyl acrylate or acrylic acid
can be recovered and reused. Slow addition of the amine salt to a solution of the catalyst and methyl acrylate
or acrylic acid gives excellent yields of cross products for the longer chain alkenes, even when using only 1%
catalyst, and especially when tosylate salts are used. The ruthenium residues from the metathesis catalyst can
be used as catalysts for the hydrogenation of both homodimeric unsaturated diamine salts and the unsaturated
cross metathesis aminoacid salts to give Nylon precursors of different chain lengths.
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Experimental
Procedure for cross-metathesis of unsaturated ammonium salts with acrylates
The following is an example of a conventional crossꢀmetathesis of alkenyl ammonium salts with methyl
acrylate (e.g. Table 1, Entry 5): Under an inert atmosphere of nitrogen, a Schlenk tube was charged with allyl
ammonium triflate (2, 35 mg, 0.17 mmol), 20 equivalents of methyl acrylate 3, HoveydaꢀGrubbs second
generation catalyst (5 mg, 5 mol%) and a small magnetic stir bar. The EtOAc (2.5 mL) was added through a
rubber septum and the tube was sealed and heated at reflux under nitrogen for 24 hours. The crude reaction
mixture was then diluted with water (4 mL) and the phases were separated. The organic phase was further
extracted with water (3×4 mL). The combined aqueous phase was washed with EtOAc (4 mL) and then
1
concentrated in vacuo to give a hygroscopic yellow oil (51 mg). H n.m.r. spectroscopy showed >95%
conversion to the desired cross product 5.
Reaction optimisation studies were performed with allylammonium triflate (2) and methyl acrylate (3) as
follows:
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• In Table 1, molar equivalents of methyl acrylate (3) were varied from 1:20 relative to the substrate
(2).
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• In Table 2, the loading of HoveydaꢀGrubbs second generation catalyst (8) was varied from 0.1 – 5
mol%.
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• In Table 3, methyl acrylate (3) was recovered and recycled in subsequent reactions. At cycle
completion, the reaction was cooled to room temperature and connected to a vacuum line (0.1
mmHg). The reaction solvent and (3) were distilled from the reaction into a new vessel. Catalyst (1
mol%) and substrate were then added maintaining the substrate:(3) ratio at 1:20.
Methyl 4-ammonium but-2-enoate triflate
Allyl ammonium triflate (35 mg) gave title ester (51 mg, 98%) as an oil (Table 1, Entry 5).
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MeOD), (E)ꢀIsomer: δ 6.92 (dt, J = 15.9, 5.8 Hz, 1H), 6.24 – 6.12 (m, 1H), 3.83 – 3.70 (m, 5H). C n.m.r.
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(100 MHz, MeOD) δ 167.1, 139.7, 126.0, 121.8 (q, J = 318 Hz), 52.4, 40.0. H n.m.r. (400 MHz, MeOD),
(Z)ꢀIsomer: δ 6.33 (dt, J = 12.1, 6.1 Hz, 1H), 6.20 – 6.09 (m, 1H), 4.14 (dd, J = 6.1, 1.8 Hz, 2H), 3.83 – 3.70
(m, 3H). 13C n.m.r. (100 MHz, MeOD) δ 167.3, 140.2, 125.1, 121.8 (q, J = 318 Hz), 52.2, 38.7. HRMS
(ESI/FTMS): m/z [MꢀTfOH+H]+ Calcd for C5H10NO2 116.0706; Found 116.0710.
Methyl 4-ammonium but-2-enoate tetrafluoroborate
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Product did not crystallise, 81% conversion by 1H n.m.r. spectroscopy.
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IR: νmax 3266m, 2963m, 1712s, 1502s, 1001s, 975s, 866s, 732s cmꢀ1. H n.m.r. (400 MHz, MeOD), (E)ꢀ
Isomer: δ 6.92 (dt, J = 15.9, 6.0 Hz, 1H), 6.17 (dt, J = 15.9, 1.7 Hz, 1H), 3.79 – 3.77 (m, 2H), 3.76 (s, 3H).
13C n.m.r. (100 MHz, MeOD) δ 167.1, 139.9, 126.1, 52.5, 41.0. 1H n.m.r. (400 MHz, MeOD), (Z)ꢀIsomer: δ
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6.33 (dt, J = 11.5, 6.2 Hz, 1H), 6.12 (dt, J = 11.5, 1.9 Hz, 1H), 4.18 – 4.07 (m, 2H), 3.75 (s, 3H). C n.m.r.
(100 MHz, MeOD) δ 167.3, 140.5, 125.1, 52.3, 38.9. HRMS (ESI/FTMS): m/z [MꢀHBF4+H]+ Calcd for
C5H10NO2 116.0706; Found 116.0703.
Methyl 4-ammonium but-2-enoate tosylate
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Product did not crystallise, 26% conversion by H n.m.r. spectroscopy. H n.m.r. (400 MHz, MeOD) δ 7.70
(d, J = 8.2 Hz, 2H), 7.23 (d, J = 7.9 Hz, 2H), 6.90 (dt, J = 15.9, 5.9 Hz, 1H), 6.15 (dt, J = 15.9, 1.6 Hz, 1H),
3.74 (s, 3H), 3.63 – 3.46 (m, 2H), 2.73 (s, 3H). HRMS (ESI/FTMS): m/z [MꢀTsOH+H]+ Calcd for C5H10NO2
116.0706; Found 116.0705.
Methyl 5-ammonium pent-2-enoate triflate
3ꢀButenyl ammonium triflate (50 mg) gave the title ester (68 mg, 99%) as an oil (Table 4, Entry 1).
IR: νmax 3105m, 1702s, 1222s, 1165s, 1024s, 982s cmꢀ1. 1H n.m.r. (400 MHz, MeOD), (E)ꢀIsomer: δ 6.91 (dt,
J = 15.7, 7.1 Hz, 1H), 6.02 (dt, J = 15.8, 1.5 Hz, 1H), 3.73 (s, 3H), 3.16 – 3.04 (m, 2H), 2.59 (qd, J = 7.2, 1.5
Hz, 2H), (Z)ꢀIsomer: δ 6.29 (dt, J = 11.4, 7.5 Hz, 1H), 6.02 (m, 1H), 3.73 (s, 3H), 3.16 – 3.04 (m, 2H), 2.59
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(qd, J = 7.2, 1.5 Hz, 2H). 13C n.m.r. (100 MHz, MeOD) δ 167.9, 144.3, 125.2, 52.1, 39.2, 30.9. HRMS
(ESI/FTMS): m/z [MꢀTfOH+H]+ Calcd for C6H12NO2 130.0863; Found 130.0859.
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Methyl 5-ammonium pent-2-enoate tetrafluoroborate
3ꢀButenyl ammonium tetrafluoroborate (37 mg) gave title ester (57 mg, 99%) as an oil (Table 4, Entry 2).
1H n.m.r. (400 MHz, MeOD), (E)ꢀIsomer: δ 6.96 – 6.85 (dt, J = 15.7, 7.1 Hz, 1H), 6.02 (d, J = 15.7 Hz, 1H),
3.73 (s, 3H), 3.10 (t, J = 7.2 Hz, 2H), 2.59 (q, J = 7.0 Hz, 2H). 13C n.m.r. (100 MHz, MeOD) δ 168.0, 144.3,
125.1, 52.1, 39.2, 30.8. 1H n.m.r. (400 MHz, MeOD), (Z)ꢀIsomer: δ 6.29 (dt, J = 11.4, 7.5 Hz, 1H), 6.17 (d, J
= 15.9 Hz, 1H), 3.76 (s, 3H), 3.10 (t, J = 7.2 Hz, 2H), 2.59 (q, J = 7.0 Hz, 2H). 13C n.m.r. (100 MHz, MeOD)
δ 168.0, 144.4, 123.8, 51.8, 39.8, 30.8. HRMS (ESI/FTMS): m/z [MꢀHBF4+H]+ Calcd for C6H12NO2
130.0863; Found 130.0869.
Methyl 6-ammonium hex-2-enoate triflate
4ꢀPentenyl ammonium triflate (50 mg) gave the title ester (60 mg, 97%) as an oil (Table 4, Entry 3).
IR: νmax 3089m, 2958m, 1708s, 1639m, 1223s, 1160s, 1026s, 760s cmꢀ1. H n.m.r. (400 MHz, MeOD), (E)ꢀ
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Isomer: δ 6.95 (dt, J = 15.6 Hz, 6.5 Hz, 1H), 5.93 (d, J = 15.5 Hz, 1H), 3.71 (s, 3H), 3.03 – 2.87 (m, 2H),
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2.39 – 2.28 (m , 2H), 1.89 – 1.76 (m, 2H). C n.m.r. (100 MHz, MeOD) δ 168.5, 148.7, 123.0, 52.1, 40.2,
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29.7, 26.9. H n.m.r. (400 MHz, MeOD), (Z)ꢀIsomer: δ 6.38 – 6.26 (m, 1H), 5.99 – 5.85 (m, 1H), 3.74 (s,
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1H), 3.03 – 2.87 (m, 2H), 2.39 – 2.28 (m, 2H), 1.89 – 1.76 (m, 2H). C n.m.r. (100 MHz, MeOD) δ 169.7,
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148.5, 123.8, 51.9, 40.2, 29.7, 27.0. HRMS (ESI/FTMS): m/z [MꢀTfOH+H]+ Calcd for C7H14NO2 144.1019;
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Methyl 6-ammonium hex-2-enoate tetrafluoroborate
4ꢀPentenyl ammonium tetrafluoroborate (50 mg) gave the title ester (76 mg, 99%) as an oil (Table 4, Entry
4).
IR: νmax 3256m, 3207m, 2955m, 1702s, 1507s, 1439s, 1287s, 1012m, 956m, 720s cmꢀ1. 1H n.m.r. (400 MHz,
MeOD), (E)ꢀIsomer: δ 6.95 (dt, J = 15.6 Hz, 6.5 Hz, 1H), 5.93 (d, J = 15.5 Hz, 1H), 3.71 (s, 3H), 3.03 – 2.87
(m, 2H), 2.39 – 2.28 (m , 2H), 1.89 – 1.76 (m, 2H). 13C n.m.r. (100 MHz, MeOD) δ 168.5, 148.7, 123.0, 52.1
, 40.2, 29.7, 26.9. 1H n.m.r. (400 MHz, MeOD), (Z)ꢀIsomer: δ 6.38 – 6.26 (m, 1H), 5.99 – 5.85 (m, 1H), 3.74
(s, 1H), 3.03 – 2.87 (m, 2H), 2.39 – 2.28 (m, 2H), 1.89 – 1.76 (m, 2H). 13C n.m.r. (100 MHz, MeOD) δ
168.4, 149.0, 121.8, 51.9, 40.2, 29.5, 26.9. HRMS (ESI/FTMS): m/z [MꢀHBF4+H]+ Calcd for C7H14NO2
144.1019; Found 144.1024.
Methyl 6-ammonium hex-2-enoate tosylate
4ꢀPentenyl ammonium tosylate (50 mg) gave the title ester (76 mg, 99%) as an oil (Table 4, Entry 5).
IR: νmax 3061m, 2950m, 2087m, 1717s, 1649s, 1493s, 1438s, 1313s, 1277s, 1178s, 1037s, 816s, 684s cmꢀ1.
1H NMR (400 MHz, MeOD), (E)ꢀIsomer: δ 7.70 (d, J = 8.0 Hz, 2H), 7.24 (d, J = 7.6 Hz, 2H), 6.92 (dt, J =
15.6 Hz, 6.5 Hz, 1H), 5.89 (d, J = 15.5 Hz, 1H), 3.71 (s, 3H), 2.92 – 2.90 (m, 2H), 2.37 (s, 3H), 2.29 – 2.27
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(m, 2H), 1.79 – 1.78 (m, 2H). 13C n.m.r. (100 MHz, MeOD): δ 168.3, 148.6, 143.3, 141.7, 129.8, 126.8,
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122.8, 52.0, 40.5, 29.6, 26.8, 21.2. H NMR (400 MHz, MeOD), (Z)ꢀIsomer: δ 6.27 (dt, 1H), 5.86 (d, 1H),
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3.73 (s, 3H), 2.88 – 2.86 (m, 2H), 2.37 (s, 3H), 2.22 – 2.20 (m , 2H), 1.70 – 1.68 (m, 2H). 13C n.m.r. (100
MHz, MeOD): δ 168.3, 148.6, 143.3, 141.7, 129.8, 126.8, 122.8, 52.0, 40.5, 29.6, 26.8, 21.2. HRMS
(ESI/FTMS): m/z [MꢀTsOH+H]+ Calcd for C7H14NO2 144.1019; Found 144.1021.
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The reaction was also performed on larger scale. 4ꢀPentenyl ammonium tosylate (1.10 g) gave the title ester
(1.30 g, 99%) as an oil.
Methyl 11-ammonium undec-2-enoate tetrafluoroborate
9ꢀUndecenyl ammonium tetrafluoroborate (100 mg) gave the title ester (78 mg, 99%) as an oil (Table 4,
Entry 6). Isomerisation observed by LRMS.
1H n.m.r. (400 MHz, MeOD), (E)ꢀIsomer: δ 6.96 (dt, J = 15.6, 7.0 Hz, 1H), 5.84 (dt, J = 15.6, 1.6 Hz, 1H),
3.70 (s, 3H), 2.91 (t, J = 7.6 Hz, 2H), 2.28 – 2.17 (m, 2H), 1.76 – 1.28 (m, 12H). 13C n.m.r. (100 MHz,
MeOD) δ 168.9, 151.3, 121.8, 51.9, 40.8, 33.1, 30.1, 30.1, 30.0, 29.1, 28.5, 27.3. HRMS (ESI/FTMS): m/z
[M±(CH2)nꢀHBF4+H]+ Calcd for C12H24NO2 214.1802; Found 214.1802 ± 14n.
Methyl 11-ammonium undec-2-enoate tosylate
9ꢀUndecenyl ammonium tosylate (100 mg) gave the title ester (78 mg, 99%) as an oil (Table 4, Entry 7).
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IR: νmax 3134m, 3050m, 2923m, 2854s, 2059m, 1719s, 1656s, 1492s, 1436s, 1176s, 1124s, 1036s, 1012s,
815s, 683s cmꢀ1. 1H NMR (400 MHz, MeOD), (E)ꢀIsomer: δ 7.70 (d, 2H), 7.23 (d, J = 8.0 Hz, 2H), 6.96 (dt,
J = 15.6, 7.0 Hz, 1H), 5.84 (dt, J = 15.6, 1.6 Hz, 1H), 3.70 (s, 3H), 2.91 (t, J = 7.6 Hz, 2H), 2.28 – 2.17 (m,
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2H), 1.76 – 1.28 (m, 12H). C NMR (100 MHz, MeOD) δ 168.6, 151.1, 121.6, 143.3, 141.5, 129.6, 126.7,
51.7, 40.6, 32.8, 30.0, 29.9, 28.9, 28.8, 28.3, 27.2, 21.2. HRMS (ESI/FTMS): m/z [M±(CH2)nꢀTsOH+H]+
Calcd for C12H24NO2 214.1802; Found 214.1804 ± 14n.
4-Ammonium but-2-enoic acid triflate
Allyl ammonium triflate (50 mg) gave the title acid (59 mg, 98%) as an oil (Table 4, Entry 8).
IR: νmax 3239m, 2873m, 1690s, 1226s, 1167m, 1028m, 868s cmꢀ1. 1H n.m.r. (400 MHz, MeOD), (E)ꢀIsomer:
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MeOD), (Z)ꢀIsomer: δ 6.31 (dt, J = 12.1, 6.1 Hz, 1H), 6.14 – 6.10 (m, 1H), 4.12 (dd, J = 6.2, 1.8 Hz, 2H). 13C
n.m.r. (100 MHz, MeOD) δ 168.2, 139.4, 126.8, 40.8. HRMS (ESI/FTMS): m/z [MꢀTfOH+H]+ Calcd for
C4H8NO2 102.0550; Found 102.0554.
5-Ammonium pentenoic acid tetrafluoroborate
Butenyl ammonium tetrafluoroborate (37 mg) gave the title acid (72 mg, 99%) as an oil (Table 4, Entry 9).
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IR: νmax 3410m, 3158m, 1708m, 1508m, 1224m, 1005s, 944m cmꢀ1. H n.m.r. (300 MHz, MeOD), (E)ꢀ
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isomer: δ 6.89 (dt, J = 15.6, 7.0 Hz, 1H), 5.98 (d, J = 15.7 Hz, 1H), 3.09 (t, J = 7.3 Hz, 2H), 2.58 (qd, J = 7.2,
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1.4 Hz, 2H). C n.m.r. (75 MHz, MeOD) δ 169.1, 144.2, 126.2, 39.2, 30.0. H n.m.r. (300 MHz, MeOD),
(Z)ꢀisomer: δ 6.26 (dt, J = 11.3 Hz, 7.5 Hz, 1H), 6.07 – 5.89 (m, 1H), 3.03 – 2.94 (m, 2H), 2.46 – 2.35 (m,
2H). 13C n.m.r. (75 MHz, MeOD) δ 169.1, 144.2, 126.2, 39.8, 27.9. HRMS (ESI/FTMS): m/z [MꢀHBF4+H]+
Calcd for C5H10NO2 116.0706; Found 116.0700.
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6-Ammonium hex-2-enoic acid tetrafluoroborate
4ꢀPentenyl ammonium tetrafluoroborate (50 mg) gave the title acid (76 mg, 99%) (Table 4, Entry 10).
Product (E)ꢀIsomer (44 mg) precipitated from EtOAc, 70% yield.
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Colourless solid, m.p. 191 °C. H N.M.R. (400 MHz, MeOD), (E)ꢀIsomer:δ 6.93 (dt, J = 15.5, 6.8 Hz, 1H),
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MHz, MeOD) δ 169.7, 148.4, 123.9, 40.2, 29.7, 27.0. HRMS (ESI/FTMS): m/z [MꢀHBF4+H]+ Calcd for
C6H12NO2 130.0863; Found 130.0865.
6-Ammonium hex-2-enoic acid triflate
4ꢀPentenyl ammonium triflate (100 mg) gave the title acid (140 mg, 99%) (Table 4, Entry 11). Product (E)ꢀ
Isomer (135 mg) precipitated from EtOAc, 95% yield.
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IR: νmax 3098m, 2977m, 1703m, 1647m, 1499s, 1223s, 1069s, 1027s, 980s, 816s cmꢀ1. H n.m.r. (400 MHz,
MeOD), (E)ꢀIsomer:δ 6.93 (dt, J = 15.6, 6.8 Hz, 1H), 5.88 (d, J = 15.6 Hz, 1H), 2.97 – 2.93 (m, 2H), 2.34 –
2.32 (m, 2H), 1.84 ꢀ1.80 (m, 2H). 13C n.m.r. (100 MHz, MeOD) δ 169.7, 148.5, 123.8, 40.2, 29.7, 27.0.
HRMS (ESI/FTMS): m/z [MꢀTfOH+H]+ Calcd for C6H12NO2 130.0863; Found 130.0863.
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6-Ammonium hex-2-enoic acid tosylate
4ꢀPentenyl ammonium tosylate (50 mg) gave the title acid (72 mg, 99%) (Table 4, Entry 12).
IR: νmax 3050m, 2917m, 2085m, 1690m, 1633s, 1492s, 1421s, 1177s, 1125s, 1012s, 974s, 819s, 682s cmꢀ1.
1H NMR (400 MHz, MeOD), (E)ꢀIsomer: δ 7.71 (d, 2H), 7.39 (d, J = 7.6 Hz, 2H), 7.01 (dt, J = 15.6, 6.8 Hz,
1H), 5.95 (d, J = 15.6 Hz, 1H), 2.42 (s, 3H), 3.05 – 3.01 (m, 2H), 2.36 – 2.33 (m, 2H), 1.88 ꢀ1.85 (m, 2H).
13C n.m.r. (100 MHz, MeOD): δ 170.5, 149.6, 142.5, 139.5, 129.4, 125.4, 121.4, 38.8, 28.3, 25.0, 20.5.
HRMS (ESI/FTMS): m/z [MꢀTsOH+H]+ Calcd for C6H12NO2 130.0863; Found 130.0864.
11-Ammonium undec-2-enoic acid tosylate
9ꢀUndecenyl ammonium tosylate (100 mg) gave the title acid (78 mg, 99%) as an oil (Table 4, Entry 13).
IR: νmax 3437m, 3055m, 2953m, 2082m, 1678s, 1492s, 1280s, 1176m, 1122s, 1009s, 816s, 680s cmꢀ1. H
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7.0 Hz, 1H), 5.81 (dt, J = 15.6, 1.6 Hz, 1H), 2.89 (t, J = 7.6 Hz, 2H), 2.37 (s, 3H), 2.23ꢀ2.21 (m, 2H), 1.63–
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30.0, 29.9, 28.9, 28.3, 27.2, 21.2. HRMS (ESI/FTMS): m/z [M±(CH2)nꢀTsOH+H]+ Calcd for C11H22NO2
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Procedure for slow addition of unsaturated ammonium salts to mixtures of acrylates and catalyst
The following is an example of a conventional slow addition of alkenyl ammonium salts to mixtures of
acrylates and catalyst: Under an inert atmosphere of nitrogen, a Schlenk tube was charged with Hoveydaꢀ
Grubbs second generation catalyst (1 or 5 mol%) and 2 equivalents of methyl acrylate in EtOAc (1 mL) and a
small magnetic stir bar. The unsaturated ammonium salts (50ꢀ100 mg) in EtOAc (2 mL) were injected
through a rubber septum with the aid of a syringe pump (flow rate 0.3 mL/min) and after complete addition
the tube was sealed and heated at reflux under nitrogen for half an hour. The reaction mixture was then
diluted with water (4 mL) and the phases separated. The organic phase was further extracted with water (3×4
mL). The combined aqueous phase was washed with EtOAc (4 mL) and then concentrated in vacuo to give
1
the crude reaction product. H n.m.r. spectroscopy showed conversion to the desired cross product in all
cases.
A tosylate reaction involved addition of undecenyl ammonium tosylate salt (100 mg, 0.29 mmol) in EtOAc
(2mL) to a mixture of methyl acrylate (0.05 mL, 0.58 mmol) and HoveydaꢀGrubbs second generation
catalyst (2 mg, 1 mol%) over one hour. The reaction was heated at reflux for 0.5 hours. The product was
isolated as described above to give the target product 10 (n=8, 78 mg, 70% yield).
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Procedure for tandem self-metathesis-hydrogenation of unsaturated ammonium salts ꢀ diamine salts
(1)
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The following is an example of a conventional tandem metathesis / hydrogenation procedure for the
metathesis of alkenyl ammonium salts (e.g. Table 5, Entry 1): Under an inert atmosphere of nitrogen, a
Schlenk tube was charged with 3ꢀbutenyl ammonium triflate (33 mg, 0.16 mmol), HoveydaꢀGrubbs second
generation catalyst (5 mg, 5 mol%) and a small magnetic stir bar. The EtOAc (4mL) was added through a
rubber septum and the tube was sealed and heated at reflux under nitrogen for 16 hours. The crude reaction
mixture was then exposed to air and concentrated in vacuo, reꢀdissolved in methanol (2mL) and transferred
to a FischerꢀPorter pressure tube. The tube was evacuated thrice with hydrogen, charged to a final pressure of
60 psi and left to stir at ambient temperature for 16 hours. The vessel was then vented to air and the solvent
was removed by rotary evaporation. The resultant mixture was dissolved in a minimum volume of acetone,
triturated with excess diethyl ether (approx 1:10) and filtered (or centrifuged) to give 1,4ꢀdiammoniumꢀ2ꢀ
butane triflate (28 mg, 91%) as an offꢀwhite solid.
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Butane-1,4-diammonium ditriflate
Allyl ammonium triflate (33 mg) gave the title diamine salt (28 mg, 91% yield) (Table 5, Entry 1).
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Precipitated from acetone with ether (approx 1: 10) to give an offꢀwhite solid, m.p. 208°C (dec). H n.m.r.
(400 MHz, MeOD): δ 3.03ꢀ2.93 (m, 2H), 1.80ꢀ1.68 (m, 2H). 13C n.m.r. (150 MHz, MeOD): 121.7 (q, J = 317
Hz), 40.1, 25.6. HRMS (ESI/FTMS): m/z [Mꢀ2TfOH+H]+ Calcd for C4H13N2 89.1073; Found 89.1080.
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Butane-1,4-diammonium ditetrafluoroborate
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Allyl ammonium tetrafluoroborate (50 mg) gave the title diamine salt (89 mg, 99% yield) (Table 5, Entry 2).
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Precipitated from acetone with ether (approx 1: 10) to give an offꢀwhite solid, m.p. 199°C (dec). H n.m.r.
(400 MHz, MeOD): δ 3.06 – 2.84 (m, 2H), 1.82 – 1.64 (m, 2H). 13C n.m.r. (100 MHz, MeOD): δ 40.1, 25.5.
HRMS (ESI/FTMS): m/z [Mꢀ2HBF4+H]+ Calcd for C4H13N2 89.1073; Found 89.1073.
Hexane-1,6-diammonium ditosylate
3ꢀButenyl ammonium tosylate (50 mg) gave the title diamine salt (89 mg, 99% yield) (Table 5, Entry 3).
Precipitated from acetone as an offꢀwhite solid, m.p. 172°C. 1H n.m.r. (400 MHz, MeOD): δ7.71 (d, J = 8.1
Hz, 2H), 7.24 (d, J = 8.0 Hz, 2H), 3.02 – 2.84 (t, J = 7.8 Hz, 2H), 1.76 – 1.58 (m, 2H), 1.51 – 1.32 (m, 2H).
13C n.m.r. (100 MHz, MeOD): δ 143.5, 141.8, 129.9, 126.9, 40.6, 28.3, 26.8, 21.3. HRMS (ESI/FTMS): m/z
[Mꢀ2TsOH+H]+ Calcd for C6H17N2 117.1386; Found 117.1391.
Octadecane-1,18-diammonium ditosylate
9ꢀUndecenyl ammonium tosylate (50 mg) gave the title diamine salt (89 mg, 99% yield) (Table 5, Entry 4).
Precipitated from acetone as a colourless solid. 1H n.m.r. (400 MHz, MeOD): δ 7.71 (d, J = 8.2 Hz, 2H), 7.23
13
(d, J = 8.0 Hz, 2H), 3.03 – 2.72 (m, 2H), 2.37 (s, 3H), 1.64 (p, 7.4 Hz, 2H), 1.53ꢀ1.20 (m, 14H). C n.m.r.
(100 MHz, MeOD) δ 141.7, 129.8, 127.0, 40.8, 30.9, 30.8, 30.8, 30.7, 30.6, 30.3, 28.6, 27.5, 21.3,
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Quaternary ArꢀCꢀSO3H not observed. LRMS (ESI/FTMS): m/z [Mꢀ2TsOH+H]+ Calcd for C18H41N2 143.1;
Found 143.1. HRMS conditions failed to yield a molecular ion for this compound.
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Procedure for tandem cross-metathesis/hydrogenation of unsaturated ammonium salts ꢀ Nylon 4, 5
and 6 monomers
The following is an example of a conventional tandem metathesis / hydrogenation procedure for the
metathesis of alkenyl ammonium salts (e.g. Table 6, Entry 1): Under an inert atmosphere of nitrogen, a
Schlenk tube was charged with allyl ammonium triflate (35 mg, 0.17 mmol), 20% methyl acrylate in EtOAc
(1.53 mL, 3.4 mmol), HoveydaꢀGrubbs second generation catalyst (5 mg, 5 mol%) and a small magnetic stir
bar. The EtOAc (4mL) was added through a rubber septum and the tube was sealed and heated at reflux
under nitrogen for 24 hours (unless specified otherwise). The crude reaction mixture was then exposed to air
and concentrated in vacuo, reꢀdissolved in methanol (4 mL) and transferred to a FischerꢀPorter pressure tube.
The tube was evacuated thrice with hydrogen, charged to a final pressure of 90 psi and left to stir at 60 °C for
16 hours. The vessel was then vented to air and the solvent was removed by rotary evaporation. The mixture
was reꢀdissolved in EtOAc (4 mL), diluted with water (4 mL) and the phases were separated. The organic
phase was further extracted with water (3×4 mL), and the combined aqueous extract was washed with EtOAc
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(4 mL) and concentrated in vacuo to give a hygroscopic yellow oil (67 mg). H n.m.r. spectroscopy showed
>95% conversion to the desired hydrogenated cross product.
Methyl 4-ammonium butanoate triflate
Allyl ammonium triflate (35 mg) gave the title ester (67 mg, 99%) (Table 6, Entry 1).
Product did not crystallise, ~ quantitative conversion by 1H n.m.r. spectroscopy.
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1H n.m.r. (400 MHz, MeOD): δ 3.69 (s, 3H), 2.99 (t, J = 7.6 Hz, 2H), 2.48 (t, J = 7.2 Hz, 2H), 1.95 (p, J =
7.4 Hz, 2H). 13C n.m.r. (100 MHz, MeOD) δ 174.6, 52.3, 40.1, 31.4, 23.7. HRMS (ESI/FTMS): m/z [Mꢀ
TfOH+H]+ Calcd for C5H12NO2 118.0863; Found 118.0864.
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Methyl 5-ammonium pentanoate tetrafluoroborate
3ꢀButenyl ammonium tetrafluoroborate (37 mg) gave the title ester (39 mg, 99%) (Table 6, Entry 2). Product
did not crystallise, ~ quantitative conversion by 1H n.m.r. spectroscopy.
1H n.m.r. (400 MHz, MeOD) δ 3.67 (s, 3H), 3.03 – 2.88 (m, 2H), 2.47 – 2.36 (m, 2H), 1.77 – 1.62 (m, 4H).
13C n.m.r. (100 MHz, MeOD) δ 175.4, 52.1, 40.5, 34.0, 27.9, 22.7. HRMS (ESI/FTMS): m/z [MꢀHBF4+H]+
Calcd for C6H14NO2 132.1019; Found 132.1021.
Methyl 6-ammonium hexanoate tetrafluoroborate
4ꢀPentenyl ammonium tetrafluoroborate (97 mg) gave title ester (124 mg, 95%) (Table 6, Entry 3).
Product did not crystallise.
IR: νmax 3275m, 2942m, 1716s, 1509s, 1219s, 1004m, 946m, 824s, 771s, 746s, 680s cmꢀ1. H n.m.r. (400
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MHz, MeOD) δ 3.66 (s, 3H), 2.93 (t, J = 7.5 Hz, 2H), 2.36 (t, J = 7.3 Hz, 2H), 1.72 – 1.61 (m, 2H), 1.47 –
1.36 (m, 4H). 13C n.m.r. (100 MHz, MeOD) δ 175.8, 52.1, 40.7, 34.4, 28.2, 26.8, 25.4. HRMS (ESI/FTMS):
m/z [MꢀHBF4+H]+ Calcd for C7H16NO2 146.1176; Found 146.1175.
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6-Ammonium hexanoic acid tetrafluoroborate
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4ꢀPentenyl ammonium tetrafluoroborate (50 mg) gave the crude title acid (102 mg, 97%) (Table 6, Entry 4).
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Product did not crystallise. H n.m.r. spectroscopy revealed a mixture of the title compound, methyl 6ꢀ
ammonium hexanoate tetrafluoroborate and succinic acid (1H n.m.r. (400 MHz, MeOD): δ 2.57 (s, 4H)),
which was not removed by aqueous extraction.
1H n.m.r. (400 MHz, MeOD): δ 2.93 (t, J = 7.5 Hz, 2H), 2.33 (t, J = 7.3 Hz, 2H), 1.76 – 1.57 (m, 4H), 1.53 –
1.32 (m, 2H). 13C n.m.r. (75 MHz, MeOD) δ 40.6, 34.3, 28.2, 26.8, 25.4, C1 not observed. LRMS
(ESI/FTMS): m/z [MꢀHBF4+H]+ Calcd for C6H14NO2 132.1; Found 132.1.
The crude amino acid mixture was added to methanol (20 mL) containing 3 drops of 40% aqueous HBF4.
The mixture was stirred at 70 °C for 72 hours. The mixture was then concentrated in vacuo and partitioned
between EtOAc (15 mL) and water (15 mL) and the phases were separated. The organic phase was further
extracted with water (3×15 mL) and the combined aqueous extract was washed with EtOAc (15 mL) and
concentrated in vacuo to give methyl 6ꢀammonium hexanoate tetrafluoroborate as an oil (90 mg, >95%
conversion by 1H n.m.r. spectroscopy). Spectral data were consistent with those reported previously.
Acknowledgements
We acknowledge the Australian Research Council (ARC) for financial assistance (Discovery Grant
DP120104169) and an Australian Postgraduate Award (to N. D. S.).
Supplementary information
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Electronic Supplementary Information is available: Spectral data for new compounds.
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References and Footnotes
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1. Biermann, U.; Friedt, W.; Land, S.; Lühs, W.; Machmüller, G.; Metzger, J. O.; Klaas, M. R. g.; Schäfer H.
J.; Schneider, M. Angew. Chem., 2000, 112, 2292ꢀ2310.
2. Kohan, M. I. Nylon Plastics, ed. Kohan, M. I., Wiley Interscience, 1973, pp. 13ꢀ82.
3. Stanyl(R) Introduction, DSM Engineering Plastics, 2004.
4. Devaux, J.ꢀF.; Le G.; Pees, B. Application of Eco-Profile Methodology To Polyamide 11, Arkema Inc.
5. Bonner, R. M.; Kohan, M. I.; Lacey, E. M.; Richardson, P. N.; Roder, T. M.; Sherwood, J. L. T. in Nylon
plastics, ed. Kohan, M. I., Wiley Interscience, 1973, pp. 327ꢀ408.
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Metathesis: Theory and Practice; Grela, K., Ed.; John Wiley & Sons, Inc.: Hoboken, NJ, USA. doi:
10.1002/9781118711613.ch11. 2014.
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ChemSusChem, 2012, 5(8), 1410ꢀ1414. b) Ameh Abel, G.; Oliver Nguyen, K.; Viamajala, S.; Varanasi S.;
Yamamoto, K. RSC Advances, 2014, 4,(98) 55622ꢀ55628.
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a) Miao, X.; Fischmeister, C.; Dixneuf, P. H.; Bruneau, C.; Dubois, J. ꢀL.; Couturier, J. ꢀL. Green
Chem., 2012, 14(8), 2179ꢀ2183. b) Rajendran, G.; Zheng, C.; Gaffney, A. PCT Int. Appl. 2013, WO
2013136111 A2 20130919. c) Couturier, J. ꢀL.; Dubois, J. ꢀL. PCT Int. Appl. 2013, WO 2013030481 A1
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Winkler, M.; Meier, M. A. R. Green Chem., 2014, 16(6), 3335ꢀ3340.
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Jacobs, T.; Rybak, A.; Meier, M. A. R. Applied Catalysis A:General, 2009, 353(1), 32ꢀ35.
Dubois, J. ꢀL. PCT Int. Appl. (2010), WO 2010004220 A2 20100114.
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Zhu, Y.; Patel, J.; Mujcinovic, S.; Jackson, W. R.; Robinson, A. J. Green Chem., 2006, 8, 746ꢀ749.
Yapa Mudiyanselage, A.; Viamajala, S.; Varanasi S.; Yamamoto, K. ACS Sustainable Chemistry and
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Engineering, 2014, 2(12), 2831ꢀ2836.
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Rybak, A.; Meier, M. A. R. Green Chem., 2007, 9(12), 1356ꢀ1361.
Spiccia, N. D.; Woodward, C. P.; Jackson, W. R.; Robinson, A. J. WO/2014/005196 "Processes for
producing amine compounds", PCT/AU2013/000745, July 2013.
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a) Ecker, F.; Leito, I.; Kaljurand, I.; Kütt, A.; Klamt, A.; Diedenhofen, M. J. Comp. Chem., 2009,
799ꢀ801. b) Kütt, A.; Rodima, T.; Saame, J.; Raamat, E.; Mäemets, V.; Kaljurand, I.; Koppel, I. A.;
Garlyauskayte, R. Y.; Yagupolskii, Y. L.; Yagupolskii, L. M.; Bernhardt, E.; Willner, H.; Leito, I. J. Org.
Chem., 2011, 76, 391ꢀ395.
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Teoh, E.; Campi, E. M.; Jackson, W. R.; Robinson, A. J. Chem. Comm., 2002, 53, 978ꢀ979.
Interestingly, under extended reaction conditions (24 h) and higher catalyst loading (5 mol% of 8),
higher order, preꢀformed ditosylate homodimers synthesised from 9 (n = 3 and 8) also failed to
quantiatively react with 20 eq. of methyl acrylate. In the n = 3 case, only 15% of the target CM product 10
(n = 3, X = OTs) was obtained; 54% conversion to 10 (n = 8, X = OTs) was observed for the longer chain
substrate.
21.
a) Wang, Z. J.; Spiccia, N. D.; Jackson, W. R.; Robinson, A. J. J. Pept. Sci., 2013, 8, 470. b) Wang,
Z. J.; Spiccia, N. D.; Jackson, W. R.; Robinson, A. J. WO/2014/005197 "Amino acid analogues and
methods for their synthesis", PCT/AU2013/000747, July 2013.
22.
i) Tandem metathesisꢀhydrogenation at elevated H2 pressure / temperature: a) Watson M. D.;
Wagener, K. B. Macromolecules, 2000, 33, 3196ꢀ3201. (GI, 120 p.s.i H2, 90 °C). b) Louie, J.; Bielawski,
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C. W. Grubbs, R. H. J. Am. Chem. Soc., 2001, 123, 11312ꢀ11313. (GI/GII, 800 p.s.i H2, 80 °C). c) Miao,
X.; Fischmeister, C.; Bruneau, C.; Dixneuf, P. H. ChemSusChem, 2009, 2, 542ꢀ545. (HGII, 145 p.s.i H2,
50 °C). d) Ramharter, J.; Weinstabl H.; Mulzer, J. J. Am. Chem. Soc., 2010, 132, 14338ꢀ14339. (GII, 140
p.s.i H2, 70 °C). e) Clark, J. S.; Labre, F.; Thomas, L. H. Org. Biomol. Chem., 2011, 9, 4823ꢀ4830. (HGII,
100 p.s.i H2, 70 °C). ii) Tandem metathesisꢀhydrogenation in the presence of added base: f) Schmidt B.;
Pohler, M. Org. Biomol. Chem., 2003, 1, 2512ꢀ2517. (GII, NaH). g) Camm, K. D.; Martinez Castro, N.;
Liu, Y.; Czechura, P.; Snelgrove, J. L.; Fogg, D. E. J. Am. Chem. Soc., 2007, 129, 4168ꢀ4169. (GI/GII,
NEt3). h) Miao, X.; Fischmeister, C.; Dixneuf, P. H.; Bruneau, C.; Dubois, J. L.; Couturier, J. L. Green
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Chem., 2012, 14, 2179ꢀ2183. (HGII, BuOK). i) Miao, X.; Fischmeister, C.; Bruneau, C.; Dixneuf, P. H.;
Dubois, J. L.; Couturier, J. L. ChemSusChem, 2012, 5, 1410ꢀ1414. (GII/HGII, LDA, tBuOK).
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