Simple Modular Synthetic Approaches to Asymmetric NN'N'', NN' C, or NN' P -Type Amido Pincer Ligands: Synthesis, Characterisation, and Preliminary Ligation Studies

Article abstract of DOI:10.1055/s-0035-1561953

A simple modular approach is presented which has been directed towards the synthesis of potentially monoanionic NN'N'', NN'C, and NN'P pincer-type ligands. These pincers incorporate an amide functionality derived from the skeletal structure of readily available 2-(2-aminophenyl)-4,5-dioxooxazoles. All of the pincers are synthesized in moderate yields (up to 74%) and are characterised by nuclear magnetic spectroscopy (NMR), elemental analyses, and infrared (IR) spectroscopy. X-ray crystallography is also performed on the chiral and achiral alkyl halide precursors and on an oxide derivative of a pincer with a NN'P-atom donor set. A palladium derivative of one of the NN'N''-pincers is shown to be an active catalyst for the addition of an allyl group to various benzaldehydes using n-Bu₃Sn(allyl) as allyl source.

Full text of DOI:10.1055/s-0035-1561953

SYNTHESIS
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© Georg Thieme Verlag Stuttgart · New York
2016, 48, A–I
paper
A
K. Herasymchuk et al.
Paper
Synthesis
Simple Modular Synthetic Approaches to Asymmetric NN′N′′, NN′C,
or NN′P-Type Amido Pincer Ligands: Synthesis, Characterisation,
and Preliminary Ligation Studies
Khrystyna Herasymchuka,1
Jennifer Huynha,2
Cl
two steps
O
N
ER2
NR2
PPh2
=
Li2PdCl4
O
N
52%:
allylic
O
N
Alan J. Loughb,
Pd
‡
ER2
NEt2
H
13 examples
transfer
catalyst
Laura Roces Fernándezc,
Robert A. Gossage*a
§
N
NH2
ER2 = NEt2
N
imidazolium
O
26–62% overall
O
a Department of Chemistry & Biology, Ryerson University,
350 Victoria Street, Toronto, ON M5B 2K3, Canada
gossage@ryerson.ca
b Department of Chemistry, University of Toronto, Toronto,
ON M5H 3S6, Canada
alough@chem.utoronto.ca
c Departamento de Química Orgánica e Inorgánica, Facultad
de Química, c/ Julián Clavería, n° 8, Universidad de Oviedo,
33006 Oviedo, Spain
roceslaura@uniovi.es
‡ Corresponding author for the crystallographic characterisation of compound 1.
§ Corresponding author for the crystallographic characterisation of compound 3m•oxide.
Received: 23.01.2016
Accepted after revision: 23.02.2016
Published online: 11.04.2016
aminophenyl)-4,5-dihydrooxazole skeleton (i.e., A/B,
Scheme 1).6,7 Amide bond formation via reaction of A with
2-picolinic acid yields the benchmark formally C1 symmet-
ric pincer precursor C (Scheme 1).
DOI: 10.1055/s-0035-1561953; Art ID: ss-2016-m0055-op
Abstract A simple modular approach is presented which has been di-
rected towards the synthesis of potentially monoanionic NN′N′′, NN′C,
and NN′P pincer-type ligands. These pincers incorporate an amide func-
tionality derived from the skeletal structure of readily available 2-(2-
aminophenyl)-4,5-dioxooxazoles. All of the pincers are synthesized in
moderate yields (up to 74%) and are characterised by nuclear magnetic
spectroscopy (NMR), elemental analyses, and infrared (IR) spectrosco-
py. X-ray crystallography is also performed on the chiral and achiral al-
kyl halide precursors and on an oxide derivative of a pincer with a NN′P-
atom donor set. A palladium derivative of one of the NN′N′′-pincers is
shown to be an active catalyst for the addition of an allyl group to vari-
ous benzaldehydes using n-Bu3Sn(allyl) as allyl source.
O
N
O
N
O
N
O
N
N
N
H
H
NH2
NH2
N
N
O
O
A
B
C
D
Cl
O
N
M
N
Key words pincer, oxazoline, ligands, palladium complex, allyl group
transfer
E: M = Pd
F: M = Pt
N
O
Scheme 1 Schematic representations of compounds A–F
Pincer ligands and the metal, metalloid, and main group
complexes derived from them, are currently playing a ma-
jor role in modern coordination chemistry, catalysis, mate-
rials science, and biologically directed chemical studies.3 A
pincer ligand typically consists of one or more formally an-
ionic donor atoms and these are flanked by two other do-
nor groups. The former being typically a C- or N-based frag-
ment and the latter usually consisting of heteroatom do-
nors with P, N, S, Se, in addition to carbene donors, being
commonly employed.4,5 Some time ago, we reported6 on a
new design of pincer ligand scaffold based on the inde-
pendently useful organic framework derived from the 2-(2-
A chiral analogue D was likewise described (Scheme 1)
from precursor B.6 Compound C and its chiral cousin were
thereafter shown to produce pincer complexes of Pd or Pt
(i.e., M) via N–H bond rupture and formation of an amido
N–M bond resulting from the formal loss of H+.6,8,9 The κ3-
N,N′,N′′ binding mode being completed by oxazoline10–12
and pyridine N-base donation to M. These pincer complexes
(i.e., E and F, Scheme 1) were thereafter shown to be not
only useful pre-catalysts for C–C bond forming reactions,6
but also as potential therapeutic agents in anti-cancer re-
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–I

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K. Herasymchuk et al.
Paper
Synthesis
search.8 For the organometallic chemist, lengthy and ex-
pensive syntheses of ligands is a serious bottleneck to the
rapid expansion of libraries of compounds that are intend-
ed for later screening of catalytic potency. The desire to
make such pincer systems in a simple, inexpensive, and
more modular fashion is in line with our objectives to de-
sign such molecules for a whole range of applications in
both chemical synthesis and chemical biology. Herein, we
present our recent investigations into modular pincer li-
gand syntheses based on the synthetically readily obtain-
able compounds A and B. In addition, a pincer–Pd deriva-
tive of one of the materials is reported and tested for C–C
bond forming process. In this regard, it is shown to be a use-
ful catalyst in allylic group transfer chemistry.
O
N
O
N
O
Et3N
Cl
+
H
Cl
N
NH2
CH2Cl2, 2 h
0 °C to r.t.
Cl
O
A
1 (85%)
O
N
O
N
O
Et3N
Cl
+
H
N
Cl
NH2
CH2Cl2, 2 h
0 °C to r.t.
Cl
O
B
2 (86%)
Our earlier synthetic methodology used to generate C or
D employed A or B in combination with picolinoyl chloride
obtained in situ by treatment of picolinic acid (i.e., PA) with
excess SOCl2. Alternatively, amide bond formation could be
facilitated with DCC/DMAP protocols using pure PA and
A/B.6 Our initial attempts to expand this series of ligands
using this latter method proved ineffective when PA was re-
placed with N,N-dimethylglycine (i.e., DMG), likely due to
the insolubility of this material in the relatively non-polar
solvents previously employed. This situation can be at-
tributed to the zwitterionic nature of this compound.
Hence, the former (less environmentally benign, costly, and
poorly atom-economic) method was chosen which does
lead to the desired ω-tertiary amine compound 3a (Equa-
tion 1) in reasonable yield (47%). Despite this success, we
were concerned about the obvious necessity to use SOCl2 in
the presence of reagents containing more sensitive func-
tional groups. In addition, several of our desired new ligand
designs required currently unavailable or synthetically
challenging R-COOH compounds. Therefore, this prompted
us to pre-modify A/B to allow for simpler and less expen-
sive modification of the ligand platform.
Equation 2 Synthetic route to compounds 1 and 2
Nucleophilic attack at the chloromethyl group was thus
investigated as a new stratagem with the intention to pro-
duce a library of ligands using simple and inexpensive sec-
ondary amine reagents. This concept was then tested and
the desired ligand products 3b–j were obtained (Scheme 2),
as mildly hydroscopic materials, with N,N-diethylamine, 2-
[2-(methylamino)ethyl]pyridine, N-methyladamantane-1-
amine, pyrrolidine, di(2-picolyl)amine, 1-aza-15-crown-5,
N-allyl-N-methylamine, N-isopropyl-N-methylamine, and
N,N-diallylamine, respectively. The use of inexpensive
K2CO3 was found to be a suitable base for this process when
using MeCN as the reaction medium.14 The isolated yields
of these ligands range from 74 to 30% (Scheme 2) and all
species gave satisfactory and otherwise unsurprising spec-
troscopic and elemental analyses data.15 A diagnostic 1H
NMR signal can be used to confirm formation of the desired
ligand; the N–H signal initially corresponding to the amide
group of 1/2 (δH = 13.05 and 12.98, respectively) is shifted
considerably downfield upon reaction (see the experimen-
tal procedures). Series 3b–j was designed to offer ligands
with a variety of steric profiles (cf. 3b vs. 3d), and/or N-ba-
sicity (cf. 3e vs. 3j) at the flanking NR2 group; the presence
of groups capable of secondary metal-bonding interactions
(e.g., 3f) have also been included. Compound 3k, which
contains a potential secondary binding group in the form of
an ω-ethanol chain, required a two-step synthesis due to
the necessity to protect the OH functionality (Scheme 3).
Protective group removal occurs in situ under the base-free
reaction conditions affording product 3k directly.
1) SOCl2, neat
50 °C, 4 h
O
N
O
N
H
N
N
OH
2) A, Et3N, CH2Cl2
r.t. 12 h
O
3a (47%)
Equation 1 Synthetic route to compound 3a
Thus, reaction of A or B with 2-chloroacetyl chloride
leads to the isolation of our key ligand precursors 1 (Equa-
tion 2)13 and its chiral congener 2 in excellent yields (85 and
86%, respectively). Both of these materials were further
characterised in the solid-state by single crystal X-ray dif-
fraction methods (see Supporting Information).
The successful syntheses of 3b–k by these simple meth-
ods prompted us to investigate if materials such as 1 could
be used with other, non-N-based nucleophiles. In this re-
gard, reaction of 1 with KPPh2 following by recrystallisation
in air gives the corresponding phosphane oxide material
3m·oxide. This complex has also been characterised by sin-
gle crystal X-ray diffraction as the isolated monohydrate
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–I

C
K. Herasymchuk et al.
Paper
Synthesis
Classical pincer ligands are characterised by the pres-
ence of N- or P-donor atoms.3 In recent years however,
there have been a variety of pincers reported which contain
a potent metal-binding carbene fragment.16 We therefore
further investigated our synthetic protocols to form a car-
bene precursor derivative. Thus, reaction of pre-formed 1-
benzyl-1H-imidazole with 3 under the base-free conditions
readily yielded the desired carbene precursor 3l, in the
form of the HCl salt, in reasonable yield (57%, Figure 1).
HNR2
K2CO3 (2 equiv)
O
N
O
N
Cl
NR2
H
H
N
N
MeCN, 80 °C
O
O
1
3b-j
O
O
O
N
N
N
O
N
O
N
N
H
H
H
N
N
N
N
N
N
O
O
O
3b (69%)
3c (45%)
3d (56%)
Cl
O
N
H
N
N
N
O
N
O
N
N
N
O
H
N
H
H
O
N
N
N
N
Figure 1 Schematic representation of carbene precursor 3l
O
O
N
O
O
O
O
3e (73%)
3f (30%)
3g (67%)
With the library of ligands in hand, it was thereafter
prudent to clarify complexation with an example and in-
deed to test such material in catalysis. Our earlier work had
demonstrated facile κ3-N,N′,N′′ binding of this class of pin-
cers (i.e., LH) to a Pd metal centre via treatment with
Li2PdCl4 in MeOH solution. This process results in net loss of
HCl (de-protonation of the pincer) and 2 equivalents of LiCl,
yielding the Pd(κ3-N,N′,N′′-L)Cl product (Scheme 1,E).6 Pin-
cer 3b was chosen for testing in this regard due to its avail-
ability and favourable NMR characteristics. The reaction as
detailed above proceeded smoothly to give Pd complex 5
(Figure 2) in reasonable yield (see experimental proce-
dures).
O
N
O
N
H
N
H
N
H
N
N
N
N
O
O
O
3h (41%)
3i (66%)
3j (74%)
Scheme 2 The general reaction, schematic representations and yields
of compounds 3b–j
OH
TMSCl
(2 equiv )
H
O
N
Me3Si
N
2
N
H
O
H
N
N
HO
Et2O
35 °C, 3 h
MeCN
80 °C, 18 h
– HCl
Cl
4 (81%)
O
Cl
3k (88%)
– Me3SiOH
O
N
Pd
N
Scheme 3 The two-step synthetic route to ω-ethanol appended pincer
3k
N
O
Figure 2 Schematic representation of Pd complex 5
(Scheme 4; also see Supporting Information). The oxide
free material can be observed spectroscopically (δP = –15.8
[CDCl3]) before exposure to air and hence the phosphane
should be amenable to reactions with metal fragments in
situ.
Szabó and co-workers have pioneered the use of pincer
Pd complexes as catalysts in a variety of organic transfor-
mations,4n and notably in allyl group transfer reactions.4n,17–19
In this regard, PCP-type pincers were found to be particu-
O
N
O
N
O
N
KPPh2
[O]
Cl
H
O
P
H
H
THF, N2
–84 °C, 24 h
– KCl
N
N
N
P
O
O
O
2
3m
3m·oxide (55%)
Scheme 4 The Synthetic route to 3m·oxide
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–I

D
K. Herasymchuk et al.
Paper
Synthesis
larly effective in the transfer of an allyl group from a tin
precursor such as n-Bu3Sn(allyl) (i.e., TBAT) to aldehydes to
yield, after acidic work-up, homoallylic alcohols. Common
side reactions, such as allylic homocoupling, are suppressed
under these conditions.20 Thus, complex 5 was tested for
such chemistry using TBAT and aromatic aldehydes (Table
1) under typical protocols (see experimental procedures).
As predicted from the assumed reaction mechanism,19
EWGs are known to favour the overall process and indeed
4-nitrobenzaldehyde is converted quantitatively with 4-
methoxybenzaldehyde displaying lower conversions. In
Szabó’s seminal study on such chemistry, it was noted that
NCN (N = trialkyl or oxazoline N-donor) and C′CC′ type pin-
cers (C′ = carbene donor) of Pd were notably poorer cata-
lysts when compared with the PCP designs that were test-
ed.18,19 The data obtained here suggests that this particular
class of NN′N′′ ligands are worthy for further studies as
group transfer catalysts. Such work is currently a focus of
our on-going research efforts in this area.
periments were recorded on a Bruker Avance II 400 using CDCl3 at
400 MHz (1H), 162 MHz (31P), and 100 MHz (13C) at r.t. In all spectra,
chemical shifts were adjusted to the residual solvent peak (δ = 7.26
for the 1H resonance frequency of CHCl3 and δ = 77.16 for 13C pertain-
ing to the central resonance of 13CDCl3). Melting points were deter-
mined using a Fisher Scientific melting point (mp) apparatus with a
maximum temperature of 300 °C. The values provided for each mp
are uncorrected. IR spectra were obtained on Perkin Elmer Spectrum
One using KBr disks (for solid materials) and NaCl disks for com-
pounds in the liquid/oil phase. SiliCycle TLC plates (thickness: 250
μm) were used for TLC characterisation; visualized under UV light.
Some of the products (as specified) were purified by dry-column
flash chromatography (DCFC). The general procedure included the
sample being adsorbed onto the silica (~3 g) using a rotary evapora-
tor. Then, a 100 mL sintered glass funnel was packed with clean silica
(~12 g) and then topped with compound-adsorbed onto silica. Frac-
tions were collected individually by applying vacuum. Each fraction
consisted of total 25 mL of the solvent mixture; initially from hexanes
(25 mL) and increasing the polarity by adding EtOAc (1 mL) with each
consecutive fraction [e.g., fraction 2: hexanes (24 mL) and EtOAc (1
mL)].
2-(Dimethylamino)-N-[2-(4,4-dimethyl-4,5-dihydrooxazol-2-
yl)phenyl]acetamide (3a)
Table 1 Complex 5 Catalysed Allylation of Selected Benzaldehydesa
SOCl2 (8.81 mL, 121 mmol) was added to N,N-dimethylglycine (0.50 g,
4.9 mmol) in a 50-mL round-bottomed flask. The orange-coloured
mixture was heated to 50 °C and then stirred for 4 h (until any solids
dissolved). Excess SOCl2 was removed in vacuo from the clear, bright
yellow solution resulting in the formation of a bright yellow coloured
solid. Then, the solution of A (0.46 g, 2.4 mmol) and Et3N (0.70 mL, 5.0
mmol) in CH2Cl2 (25.0 mL) was added to the mixture which was then
stirred for 12 h at r.t. The dark orange coloured solution was then ex-
tracted with water (3 × 50 mL). The combined organic layers were
dried (MgSO4) and gravity filtered, resulting in a transparent brown-
ish-orange coloured solution. After evaporation of the solvent, a
beige-coloured solid was formed. The compound was purified by
DCFC and the product was collected as a dark orange coloured hydro-
scopic wax from fractions 5 to 14 (0.34 g, 47% yield); Rf = 0.58 (hex-
anes–EtOAc, 4:1).
Entry
Ra
NO2
Yield (%)b
1
2
3
4
5
6
<99
0c
NO2
OMe
OMe
H
76
0c
<99
0c
H
a General formula 4-R-C6H4-CHO (see experimental procedures).
b Yields determined by 1H NMR spectroscopy.
c No 5 added.
IR (KBr): 2969, 2779, 1677, 1645, 1581, 1532, 1447, 1291, 1208, 1053,
The synthesis and characterisation of small library of
potential N,N′,N′′ pincer ligands has been realised. The use
of a key alkyl chloride derivative considerably widens the
potential scope of this library and indeed examples of both
N,N′P and N,N′-carbene pincer precursors have also been
synthesised. A Pd chlorido complex of one of the N,N′,N′′
pincers has been made and it is shown to be an active cata-
lysts for allyl group transfer chemistry. Future work based
on these studies will include a further exploration of chiral
pincers obtained from 2, enantioselective catalytic screen-
ing, and the use of new pincers in bio-inorganic chemistry;
these results will be reported in due course.
1044, 963, 877, 753, 689 cm–1
.
1H NMR: δ = 1.40 (s, 6 H), 2.39 (s, 6 H), 3.16 (s, 2 H), 4.05 (s, 2 H), 7.07
(t, J = 8.0 Hz, 1 H), 7.44 (t, J = 8.0 Hz, 1 H), 7.83 (dd, J = 8.0, 4.0 Hz, 1 H),
8.84 (d, J = 12.0 Hz, 1 H), 12.80 (s, 1 H).
13C NMR: δ = 28.6, 46.0, 64.5, 68.1, 77.7, 114.1, 119.8, 122.3, 129.0,
132.2, 139.5, 161.1, 171.0.
Anal. Calcd for C15H21N3O2·0.25H2O: C, 64.38; H, 7.74; N, 15.02.
Found: C, 64.88; H, 7.66; N, 15.00.
2-Chloro-N-[2-(4,4-dimethyl-4,5-dihydrooxazol-2-yl)phenyl]acet-
amide (1)
The solution of A (1.70 g, 8.94 mmol) and Et3N (1.86 mL, 13.3 mmol)
in CH2Cl2 (25 mL) in a round-bottomed flask was placed into an ice
bath and stirred for 15 min. 2-Chloroacetyl chloride (0.78 mL, 9.8
mmol) was then added dropwise over 5 min to the stirred solution.
Upon completion of the addition, the contents of the reaction vessel
were stirred for 2 h at r.t. Over that period of time, the colour of the
solution changed from yellow to orange and finally to deep red; a pale
pink precipitate was also noted. After 2 h, the dark red solution was
gravity filtered and the filtrate was left to evaporate overnight. Dark
brown crystals formed and were washed with Et2O (20 mL), resulting
All reactions were carried out under an ambient atmosphere unless
otherwise stated. All chemicals were purchased commercially and
were used without further purification. Solvents used for reactions
were supplied by an mBraun Solvent Purification System (SPS) or
commercial suppliers, none of which were further purified. Com-
pounds A and B were synthesized according to literature.21,22 NMR ex-
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–I

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K. Herasymchuk et al.
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Synthesis
in an orange solution and a black-coloured precipitate. The mixture
was gravity filtered. The product was isolated as orange-coloured
crystalline solid (2.02 g, 85% yield); mp 97–99 °C; Rf = 0.62 (hexanes–
EtOAc, 4:1).
13C NMR: δ = 12.1, 28.7, 49.3, 58.2, 68.4, 77.8, 114.3, 120.1, 122.4,
129.3, 132.2, 139.6, 161.1, 172.8.
Anal. Calcd for C17H25N3O2: C, 67.30; H, 8.31; N, 13.85. Found: C,
67.52; H, 8.20; N, 13.75.
IR (KBr): 2953, 1675, 1639, 1609, 1589, 1535, 1450, 1355, 1303, 1057,
1046, 959, 776, 690 cm–1
.
N-[2-(4,4-Dimethyl-4,5-dihydrooxazol-2-yl)phenyl]-2-{methyl[2-
1H NMR: δ = 1.41 (s, 6 H), 4.07 (s, 2 H), 4.21 (s, 2 H), 7.13 (ddd, J = 1.2,
7.6, 8.0 Hz, 1 H), 7.47 (dddd, J = 0.4, 2.0, 7.6, 8.8 Hz, 1 H,), 7.85 (ddd,
J = 0.4, 2.0, 8.0 Hz, 1 H), 8.74 (dd, J = 1.2, 8.8 Hz, 1 H), 13.05 (s, 1 H).
13C NMR: δ = 28.6, 43.7, 68.2, 78.1, 114.5, 120.0, 123.3, 129.1, 132.4,
139.2, 161.6, 165.9.
(pyridin-2-yl)ethyl]amino}acetamide (3c)
The compound was prepared similarly as for 3b from 2-[2-(methyl-
amino)ethyl]pyridine (0.50 mL, 3.6 mmol), 1 (0.48 g, 1.8 mmol), and
K2CO3 (0.50 g, 3.6 mmol) in MeCN (10 mL) for 23 h. The compound
was purified by DCFC and the product was collected as yellowish co-
loured powder from fractions 20 to 34 (0.30 g, 45% yield); Rf = 0.12
(hexanes–EtOAc, 3:2).
1H NMR: δ = 1.38 (s, 6 H), 2.50 (s, 3 H), 2.95–3.10 (m, 4 H), 3.31 (s, 2
H), 4.02 (s, 2 H), 7.04–7.11 (m, 2 H), 7.14 (dt, J = 8.0, 0.8 Hz, 1 H), 7.44
(ddd, J = 8.8, 7.6, 1.6 Hz, 1 H), 7.54 (td, J = 7.6, 2.0 Hz, 1 H), 7.84 (dd,
J = 8.0, 1.6 Hz, 1 H), 8.50 (ddd, J = 4.8, 2.0, 0.8 Hz, 1 H), 8.84 (dd, J = 8.4,
1.2 Hz, 1 H), 12.65 (s, 1 H).
Anal. Calcd for C13H15N2O2Cl: C, 58.54; H, 5.67; N, 10.50. Found: C,
58.40; H, 5.55; N, 10.44.
2-Chloro-N-{2-[(3aR,8aS)-3a,8a-dihydro-8H-indeno[1,2-d]oxazol-
2-yl]phenyl}acetamide (2)
A solution of B (0.50 g, 2.0 mmol) and Et3N (0.42 mL, 3.0 mmol) in
CH2Cl2 (25 mL) in a round-bottomed flask was placed into an ice bath
and stirred for 30 min. 2-Chloroacetyl chloride (0.17 mL, 2.2 mmol)
was then added dropwise over 5 min to the stirring solution. Upon
completion of the addition, the contents of the reaction vessel were
stirred for 24 h at r.t. The colour of the solution changed from yellow
to dark brown with white precipitate over the course of the reaction.
The solution was gravity filtered. Hexanes (10 mL) and then Et2O (5
mL) were used to precipitate the product out of CH2Cl2 solution. The
product was isolated as a peachy coloured crystalline solid after filtra-
tion (0.56 g, 86% yield); Rf = 0.63 (hexanes–EtOAc, 4:1).
1H NMR: δ = 1.41 (t, J = 7.6 Hz, 1 H), 3.35–3.45 (m, 1 H), 3.50–3.60 (m,
1 H), 4.25 (q, J = 14.8 Hz, 2 H), 5.47 (ddd, J = 8.4, 7.2, 2.0 Hz, 1 H), 5.86
(d, J = 8.0, 1 H), 7.13 (td, J = 7.6, 0.8 Hz, 1 H), 7.25–7.35 (m, 2 H), 7.47
(ddd, J = 8.8, 7.6, 2.0 Hz, 1 H), 7.51–7.57 (m, 1 H), 7.89 (dd, J = 8.0, 1.6
Hz, 1 H), 8.72 (dd, J = 8.4, 0.8 Hz, 1 H), 12.98 (s, 1 H).
13C NMR: δ = 28.8, 35.9, 43.6, 58.1, 62.2, 68.3, 77.8, 114.3, 120.1,
121.4, 122.5, 123.3, 129.2, 132.3, 136.5, 139.6, 149.4, 160.0, 161.2,
171.2.
Anal. Calcd for C21H26N4O2: C, 68.83; H, 7.15; N, 15.29. Found: C,
68.56; H, 7.14; N, 15.23.
2-[Adamantan-1-yl(methyl)amino]-N-[2-(4,4-dimethyl-4,5-dihy-
drooxazol-2-yl)phenyl]acetamide (3d)
The compound was prepared similarly as for 3b from N-methylada-
mantane-1-amine (0.17 g, 1.0 mmol), 1 (0.24 g, 0.90 mmol), and
K2CO3 (0.14 g, 1.0 mmol) in MeCN (20 mL) for 28 h. The compound
was recrystallized (CH2Cl2 and hexanes) as yellow-coloured hydro-
scopic wax (0.20 g, 56% yield); Rf = 0.66 (hexanes–EtOAc, 4:1).
1H NMR: δ = 1.42 (s, 6 H), 1.63 (q, J = 12.4 Hz, 6 H), 1.76 (d, J = 2.4 Hz,
6 H), 2.07–2.13 (br m, 3 H), 2.36 (s, 3 H), 3.31 (s, 2 H), 4.02, (s, 2 H),
7.06 (ddd, J = 8.0, 7.6, 0.8 Hz, 1 H), 7.44 (ddd, J = 8.8, 7.6, 1.6 Hz, 1 H),
7.88 (dd, J = 7.6, 1.2 Hz, 1 H), 8.86 (dd, J = 8.4, 0.8 Hz, 1 H), 12.24 (br s,
1 H).
13C NMR: δ = 39.8, 43.7, 76.5, 82.4, 114.2, 120.3, 123.4, 125.6, 125.8,
127.8, 129.0, 129.5, 132.8, 139.0, 139.7, 141.4, 163.8, 165.8.
Anal. Calcd for C18H15N2O2Cl: C, 66.16; H, 4.63; N, 8.57. Found: C,
65.88; H, 4.60; N, 8.50.
13C NMR: δ = 28.7, 29.6, 36.2, 36.8, 38.7, 54.4, 56.0, 68.6, 77.8, 114.6,
120.5, 122.5, 129.6, 132.2, 139.6, 161.2, 173.6.
2-(Diethylamino)-N-[2-(4,4-dimethyl-4,5-dihydrooxazol-2-yl)phe-
nyl]acetamide (3b); Typical Procedure
Anal. Calcd for C24H33N3O2·0.5H2O: C, 71.25; H, 8.47; N, 10.39. Found:
C, 71.01; H, 8.49; N, 10.39.
Compound 1 (1.27 g, 4.78 mmol) was added to a stirred solution of
K2CO3 (1.32 g, 9.55 mmol) and Et2NH (1.00 mL, 9.55 mmol) in MeCN
(30.0 mL) in a round-bottomed flask. The orange-coloured solution
was then heated to reflux temperature (~80 °C). The reaction progress
was monitored by TLC, and the reflux was stopped after 24 h. The
mixture appeared dark brown with light brown precipitate. The mix-
ture was allowed to cool to r.t., and then it was gravity filtered and
the solution was left to evaporate to give a compound that appeared
brown in colour and waxy in composition. The compound was puri-
fied by DCFC and the product was collected as a yellow-coloured oil
from fractions 8 to 18 (1.1 g, 69% yield); Rf = 0.59 (hexanes–EtOAc,
4:1).
N-[2-(4,4-Dimethyl-4,5-dihydrooxazol-2-yl)phenyl]-2-(pyrrolidin-
1-yl)acetamide (3e)
The compound was prepared similarly as for 3b from pyrrolidine
(0.58 mL, 7.0 mmol), 1 (1.20 g, 4.50 mmol), and K2CO3 (1.24 g, 9.00
mmol) in MeCN (30 mL) for 7 h. The compound was recrystallized
(CH2Cl2 and hexane) as a beige-coloured solid (0.62 g, 73% yield); mp
106–108 °C; Rf = 0.28 (hexanes–EtOAc, 4:1).
1H NMR: δ = 1.39 (s, 6 H), 1.82–1.91 (m, 4 H), 2.68–2.76 (m, 4 H), 3.37
(s, 2 H), 4.04 (s, 2 H), 7.07 (ddd, J = 8.0, 7.6, 1.2 Hz, 1 H), 7.44 (dddd,
J = 9.2, 7.2, 1.6, 0.4 Hz, 1 H), 7.84 (ddd, J = 8.0, 2.0, 0.4 Hz, 1 H), 8.83
(dd, J = 8.4, 0.8 Hz, 1 H), 12.47 (s, 1 H).
IR (NaCl): 2971, 1686, 1641, 1581, 1520, 1446, 1283, 1056, 1046, 773,
754 cm–1
.
13C NMR: δ = 24.5, 28.6, 54.7, 61.6, 68.3, 77.8, 114.3, 120.3, 122.5,
129.2, 132.3, 139.6, 161.3, 171.3.
1H NMR: δ = 1.09 (t, J = 7.2 Hz, 6 H), 1.39 (s, 6 H), 2.67 (q, J = 7.2 Hz, 4
H), 3.24 (s, 2 H), 4.04 (s, 2 H), 7.06 (ddd, J = 7.6, 7.2, 1.2 Hz, 1 H), 7.44
(dddd, J = 8.8, 7.2, 1.6, 0.4 Hz, 1 H), 7.85 (ddd, J = 8.0, 1.6, 0.4 Hz, 1 H),
8.88 (dd, J = 8.8, 1.2 Hz, 1 H), 12.64 (s, 1 H).
Anal. Calcd for C17H23N3O2: C, 67.75; H, 7.69; N, 13.94. Found: C,
67.93; H, 7.66; N, 13.96.
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2-[Bis(pyridin-2-ylmethyl)amino]-N-[2-(4,4-dimethyl-4,5-dihy-
N-[2-(4,4-Dimethyl-4,5-dihydrooxazol-2-yl)phenyl]-2-[isopro-
drooxazol-2-yl)phenyl]acetamide (3f)
pyl(methyl)amino]acetamide (3i)
The compound was prepared similarly as for 3b from di(2-pi-
colyl)amine (0.20 mL, 1.1 mmol), 1 (0.30 g, 1.1 mmol), and K2CO3
(0.31 g, 2.3 mmol) in MeCN (20 mL) for 24 h. The compound was puri-
fied by DCFC from fractions 29 to 38, then washed with Et2O and col-
lected as a white-coloured solid (0.14 g, 30% yield); Rf = 0.05 (hex-
anes–EtOAc, 1:1).
1H NMR: δ = 1.40 (s, 6 H), 3.49 (s, 2 H), 4.08 (s, 2 H), 4.12 (s, 4 H), 7.10
(ddd, J = 8.0, 7.6, 1.2 Hz, 1 H), 7.18 (ddd, J = 6.8, 5.2, 2.4 Hz, 2 H), 7.45
(ddd, J = 8.8, 7.6, 2.0 Hz, 1 H), 7.61–7.72 (m, 4 H), 7.88 (dd, J = 8.0, 2.0
Hz, 1 H), 8.55 (dt, J = 6.0, 1.2 Hz, 2 H), 8.76 (dd, J = 8.4, 0.8 Hz, 1 H),
12.57 (s, 1 H).
The compound was prepared similarly as for 3b from N-isopropyl-N-
methylamine (1.04 g, 10.0 mmol), 1 (2.67 g, 10.0 mmol), and K2CO3
(2.76 g, 20.0 mmol) in MeCN (50 mL) for 24 h. The compound was dis-
solved in CH2Cl2(30 mL) and extracted with H2O (2 × 30 mL), and then
brine (30 mL). The organic layer was dried (MgSO4). The product was
collected as orange-coloured oil (2.00 g, 66% yield); Rf = 0.14 (hex-
anes–EtOAc, 4:1).
1H NMR: δ = 1.07 (d, J = 6.8 Hz, 6 H), 1.38 (s, 6 H), 2.35 (s, 3 H), 2.93
(septet, J = 6.8 Hz, 1 H), 3.17 (s, 2 H), 4.02 (s, 2 H), 7.05 (t, J = 7.6 Hz, 1
H), 7.43 (t, J = 8.4 Hz, 1 H), 7.84 (d, J = 7.6 Hz, 1 H), 8.88 (d, J = 8.4 Hz, 1
H), 12.63 (br s, 1 H).
13C NMR: δ = 28.7, 57.9, 60.6, 68.3, 77.7, 114.1, 120.2, 122.2, 122.5,
13C NMR: δ = 18.2, 28.5, 40.2, 54.3, 57.1, 68.2, 77.6, 114.3, 120.0,
123.6, 129.2, 132.3, 136.4, 139.4, 149.2, 157.9, 161.6, 170.6.
122.3, 129.2, 132.1, 139.5, 161.0, 172.5.
Anal. Calcd for C25H27N5O2: C, 69.91; H, 6.34; N, 16.31. Found: C,
69.88; H, 6.26; N, 16.13.
Anal. Calcd for C17H25N3O2: C, 67.30; H, 8.31; N, 13.85. Found: C,
67.18; H, 8.28; N, 13.96.
N-[2-(4,4-Dimethyl-4,5-dihydrooxazol-2-yl)phenyl]-2-(1,4,7,10-
2-(Diallylamino)-N-[2-(4,4-dimethyl-4,5-dihydrooxazol-2-yl)phe-
tetraoxa-13-azacyclopentadecan-13-yl)acetamide (3g)
nyl]acetamide (3j)
The compound was prepared similarly as for 3b from 1-aza-15-
crown-5 (0.22 g, 1.00 mmol), 1 (0.27 g, 1.0 mmol), and K2CO3 (0.28 g,
2.0 mmol) in MeCN (25 mL) for 17 h. The compound was dissolved in
CHCl3(30 mL) and extracted with H2O (30 mL), and then brine (10
mL). The organic layer was dried (MgSO4). Collected as yellow-
coloured wax (0.30 g, 67% yield); Rf = 0.15 (hexanes–EtOAc, 1:1).
The compound was prepared similarly as for 3b from N,N-diallyl-
amine (0.43 mL, 3.5 mmol), 1 (0.80 g, 3.0 mmol), and K2CO3 (0.83 g,
6.0 mmol) in MeCN (25 mL). The compound was recrystallized (petro-
leum ether) as a orange-coloured hydroscopic wax (0.72 g, 74% yield);
Rf = 0.67 (hexanes–EtOAc, 4:1).
1H NMR: δ = 1.41 (s, 6 H), 3.24 (d, J = 6.8 Hz, 4 H), 3.27 (s, 2 H), 4.05 (s,
2 H), 5.15 (d, J = 10.4 Hz, 2 H), 5.21 (d, J = 17.2 Hz, 2 H), 5.97 (tdd,
J = 6.8, 10.4, 17.2 Hz, 2 H), 7.07 (t, J = 8.0 Hz, 1 H), 7.44 (dt, J = 1.6, 8.8
Hz, 1 H), 7.86 (dd, J = 1.6, 8.0 Hz, 1 H), 8.86 (d, J = 8.8 Hz, 1 H), 12.61 (s,
1 H).
IR (KBr): 3089, 2867, 1683, 1636, 1582, 1520, 1446, 1355, 1284, 1127,
1057, 968, 934, 755 cm–1
.
1H NMR: δ = 1.40 (s, 6 H), 3.04 (t, J = 6.0 Hz, 4 H), 3.48 (s, 2 H), 3.60–
3.68 (m, 12 H), 3.72 (t, J = 6.0 Hz, 4 H), 4.03 (s, 2 H), 7.06 (t, J = 7.6 Hz,
1 H), 7.43 (t, J = 8.4 Hz, 1 H), 7.84 (d, J = 8.0 Hz, 1 H), 8.82 (d, J = 8.4 Hz,
1 H), 12.52 (br s, 1 H).
13C NMR: δ = 28.6, 57.6, 58.5, 68.3, 77.6, 114.1, 118.6, 119.9, 122.3,
129.2, 132.2, 134.8, 139.5, 161.2, 171.8.
13C NMR: δ = 28.7, 54.5, 60.0, 68.2, 69.4, 70.4, 70.5, 70.9, 77.6, 114.1,
120.0, 122.4, 129.2, 132.2, 139.5, 161.2, 171.8.
Anal. Calcd for C19H25N3O2·0.25H2O: C, 68.75; H, 7.74; N, 12.66.
Found: C, 68.46; H, 7.64; N, 12.43.
Anal. Calcd for C23H35N3O6: C, 61.45; H, 7.85; N, 9.35. Found: C, 61.38;
H, 7.82; N, 9.52.
N-[2-(4,4-Dimethyl-4,5-dihydrooxazol-2-yl)phenyl]-2-[(2-hy-
droxyethyl)(methyl)amino]acetamide (3k)
In a 50-mL three-neck round bottom flask, 4 (0.22, 1.20 mmol) and
K2CO3 (0.21 g: 1.5 mmol) were dissolved in MeCN (15 mL) under an
atmosphere of N2 gas. The solution was stirred for 15 min. A solution
of 1 (0.20 g, 0.75 mmol) in MeCN (10 mL) was then added and the
mixture was stirred at reflux temperature (80 °C) for 18 h. After the
reflux was complete, the solution was filtered and allowed to evapo-
rate. The product was a light yellow coloured wax (0.20 g, 88% yield).
A satisfactory N-elemental analysis could not be obtained, vide infra.
2-[Allyl(methyl)amino]-N-[2-(4,4-dimethyl-4,5-dihydrooxazol-2-
yl)phenyl]acetamide (3h)
The compound was prepared similarly as for 3b from N-allyl-N-
methylamine (0.30 mL, 3.1 mmol), 1 (0.80 g, 3.00 mmol), and K2CO3
(0.71 g, 5.1 mmol) in MeCN (30 mL) for 48 h. The compound was puri-
fied by DCFC and the product was collected as yellowish coloured oil
from fractions 7 to 10 (0.37 g, 41% yield); Rf = 0.53 (hexanes–EtOAc,
4:1).
1H NMR: δ = 1.40 (s, 6 H), 2.43 (s, 3 H), 2.66 (t, J = 4.8 Hz, 2 H), 3.24 (s,
2 H), 3.62 (t, J = 4.8 Hz, 2 H), 4.03 (s, 2 H), 7.05 (t, J = 8.0 Hz, 1 H), 7.42
(t, J = 8.0 Hz, 1 H), 7.80 (dd, J = 8.0, 1.6 Hz, 1 H), 8.80 (d, J = 8.0 Hz, 1
H), 12.22 (br s, 1 H).
13C NMR: δ = 28.5, 44.2, 59.2, 60.8, 62.8, 68.6, 77.9, 114.3, 120.0,
122.8, 129.6, 132.6, 139.1, 162.2, 170.7.
IR (KBr): 3083, 2971, 1683, 1643, 1582, 1520, 1447, 1354, 1293, 1209,
1056, 1046, 968, 926, 773, 754, 690 cm–1
.
1H NMR: δ = 1.39 (s, 6 H), 2.38 (s, 3 H), 3.16 (dt, J = 6.8, 1.6 Hz, 2 H),
3.20 (s, 2 H), 4.03 (s, 2 H), 5.16 (ddt, J = 10.0, 2.0, 0.8 Hz, 1 H), 5.23 (dq,
J = 17.2, 1.6 Hz, 1 H), 5.95 (ddt, J = 16.8, 10.4, 6.8 Hz, 1 H), 7.06 (ddd,
J = 7.6, 7.2, 1.2 Hz, 1 H), 7.43 (dddd, J = 9.2, 7.6, 2.0, 0.4 Hz, 1 H), 7.84
(ddd, J = 8.0, 1.6, 0.4 Hz, 1 H), 8.86 (dd, J = 8.4, 0.8 Hz, 1 H), 12.71 (s, 1
H).
Anal. Calcd for C16H23N3O3: C, 62.93; H, 7.59; N, 13.76. Found: C,
62.56; H, 7.23; N, 12.06.15
13C NMR: δ = 28.6, 43.7, 61.1, 61.4, 68.2, 77.7, 114.2, 118.4, 120.0,
122.4, 129.2, 132.2, 135.2, 139.6, 161.2, 171.4.
1-Benzyl-1H-imidazole
K2CO3 (3.99 g, 28.8 mmol) and imidazole hydrochloride (1.00 g, 9.60
mmol) were dissolved in MeCN (30 mL) in a round-bottomed flask.
Benzyl bromide (1.25 mL, 10.6 mmol) was added dropwise to the
stirred solution at r.t. After 70 h, the solution was concentrated and
Anal. Calcd for C17H23N3O2: C, 67.75; H, 7.69; N, 13.94. Found: C,
67.96; H, 7.67; N, 13.73.
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–I

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K. Herasymchuk et al.
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Synthesis
the materials re-dissolved in CH2Cl2 (i.e., CH2Cl2) and then extracted
with H2O (3 × 30 mL). The organic layer was then dried (MgSO4). The
product was collected as off-white coloured wax (0.63 g, 42% yield).
1H NMR spectrum is consistent with that previously reported.23
Pd(κ3-N,N′,N′′-L)Cl (Complex 5; LH = 3b)
A solution of 3b (0.24 g, 0.79 mmol) in MeOH (5.0 mL) was cooled on
an ice bath for 5 min. Subsequently, 0.079 M Li2PdCl4 in MeOH solu-
tion (10.0 mL, 0.79 mmol) was added dropwise over a period of a few
minutes. The orange-coloured solution was then stirred at r.t. for 24
h. The solvent was removed in vacuo and the orange-coloured mate-
rial thus obtained was re-dissolved in CH2Cl2 (5.0 mL) and then fil-
tered through Celite. The product was then isolated as an orange-co-
loured hydroscopic solid following solvent evaporation; yield: 0.18 g
(52%).
1H NMR (400 MHz, CDCl3): δ = 8.30 (d, J = 8.4 Hz, 1 H), 7.65 (d, J = 7.6
Hz, 1 H), 7.37 (t, J = 7.6 Hz, 1 H), 6.96 (t, J = 7.6 Hz, 1 H), 4.21 (s, 2 H),
3.61 (s, 2 H), 3.23 (dq, J = 13.6, 6.8 Hz, 2 H), 2.43 (dq, J = 13.6, 6.8 Hz, 2
H), 1.73 (s, 6 H), 1.65 (t, J = 6.8 Hz, 6 H).
1-Benzyl-3-(2-{[2-(4,4-dimethyl-4,5-dihydrooxazol-2-yl)phe-
nyl]amino}-2-oxoethyl)-1H-imidazol-3-ium Chloride (3l)
A solution of 1 (0.40 g, 1.5 mmol) and 1-benzyl-1H-imidazole (vide
supra) (0.19 g, 1.2 mmol) in THF/MeCN (15/3 mL) was heated to re-
flux temperature in a round-bottomed flask for 24 h. The solution
was concentrated and then washed with Et2O (10 mL total). The prod-
uct was then collected as a yellow-coloured hydroscopic wax (0.29 g,
57% yield); Rf = 0.61 (hexanes–EtOAc, 4:1).
1H NMR: δ = 1.43 (s, 6 H), 4.08 (s, 2 H), 5.50 (s, 2 H), 5.54 (s, 2 H), 7.12
(t, J = 7.6 Hz, 1 H), 7.21 (br s, 1 H), 7.33–7.45 (m, 6 H), 7.47 (br s, 1 H),
7.84 (d, J = 7.6 Hz, 1 H), 8.44 (d, J = 8.4 Hz, 1 H), 10.71 (br s, 1 H), 12.96
(br s, 1 H).
13C NMR (100 MHz, CDCl3): δ = 177.3, 162.4, 144.7, 132.9, 129.4,
123.2, 121.6, 116.4, 81.6, 70.6, 63.6, 56.6, 27.9, 12.4.
Anal. Calcd for C17H24ClN3O2Pd·0.5H2O: C, 43.33; H, 5.77; N, 8.92.
Found: C, 43.57; H, 5.47; N, 8.52.
13C NMR: δ = 28.6, 52.3, 53.7, 68.2, 78.1, 114.0, 119.9, 120.8, 123.5,
123.6, 129.0, 129.2, 129.5, 129.6, 132.5, 132.6, 138.5, 139.1, 162.0,
162.6.
Catalysis: Allylation of Aldehydes
Each respective aldehyde (0.15 mmol) and a 9.0 × 10–3 M THF solu-
tion of 5 (0.007 mmol, 5 mol%) were dissolved in THF (1.0 mL). Allyl-
tributyltin (56 μL, 0.18 mmol) was added to the stirred solution at r.t.
The reaction was thereafter stirred at 60 °C for 24 h. The solvent was
removed in vacuo and the residual material was analysed by 1H NMR
spectroscopy.
Anal. Calcd for C23H25ClN4O2·0.5H2O: C, 59.93; H, 6.34; N, 12.15.
Found: C, 59.86; H, 6.27; N, 11.03.
N-[2-(4,4-Dimethyl-4,5-dihydrooxazol-2-yl)phenyl]-2-(diphenyl-
phosphoryl)acetamide (3m•oxide)
Compound 1 (0.80 g, 3.0 mmol) was dissolved in dry THF (15 mL) in a
round-bottomed flask and placed into an ice bath at –84 °C (EtO-
Ac/liquid N2). A 5.0 M KPPh2 in THF solution (6.00 mL, 3.00 mmol)
was added dropwise to the stirred solution. The solution was stirred
for 24 h under N2 at r.t., and then it was cannula transferred and the
precipitate was discarded. The compound was recrystallized (in air,
CH2Cl2/Et2O) as a yellow-coloured waxy solid in the form of the phos-
phine oxide (0.69 g, 55% yield); Rf = (hexanes–EtOAc, 4:1).
1H NMR: δ = 1.38 (s, 6 H), 3.56 (d, J = 15.6 Hz, 2 H), 4.03 (s, 2 H), 7.03
(td, J = 8.0, 1.2 Hz, 1 H), 7.34 (ddd, J = 8.8, 8.0, 1.6 Hz, 1 H), 7.40–7.53
(m, 6 H), 7.76 (dd, J = 7.6, 1.6 Hz, 1 H), 7.82–7.90 (m, 4 H), 8.45 (d,
J = 8.4 Hz, 1 H), 12.43 (s, 1 H).
X-ray Diffraction Studies
The single crystal X-ray diffraction study of compound 1 was carried
out as described previously.25 The diffraction study of compound
3m·oxide was likewise carried out as reported26 with the exception
that CuKα radiation was used as the X-ray source. Raw diffraction
data of compound 2 was supplied by the X-ray Crystallography Facili-
ty of the University of Zürich as part of the 2013 Zürich School of
Crystallography. Further details, including checkcif files, can be found
in the Supporting Information.
13C NMR: δ = 28.7, 43.06 [d, J(13C-31P) = 61.0 Hz], 68.0, 77.9, 113.7,
119.8, 122.8, 128.6, 128.7, 128.9, 131.3, 131.4, 131.5, 132.2 [d, J(13C-
31P) = 3.0 Hz], 132.3, 132.4, 139.3, 161.8, 162.7 [d, J(13C-31P) = 5.0 Hz].
Acknowledgment
This work has been supported by the Dean’s Research Fund and the
Faculty of Science of Ryerson University. R.A.G. is further indebted to
the talented instructors of the 2013 Zürich School of Crystallography
for their expert help with the structural determination, by single
crystal X-ray diffraction, of compound 2. Prof. Russell D. Viirre (Ryer-
son University) is also thanked for helpful discussions and encourage-
ment.
31P NMR: δ = +28.5.
Anal. Calcd for C25H25N2O3P·2H2O: C, 64.09; H, 6.24; N, 5.98. Found: C,
64.70; H, 5.92; N, 5.75.
N-Methyl-2-(trimethylsiloxy)ethan-1-aminium Chloride (4)24
To dry Et2O (~30.0 mL) in a round-bottomed flask attached to a reflux
condenser was added 2-(methylamino)ethanol (1.07 mL, 13.3 mmol)
and the mixture was stirred for 5 min under an atmosphere of N2.
TMSCl (3.34 mL, 26.7 mmol) was then added dropwise to the flask.
The mixture was then refluxed for 3 h. After reflux, volatiles were re-
moved in vacuo yielding a white-coloured fluffy solid (1.98 g, 81%
yield). Spectroscopic data are consistent with known values.24
Supporting Information
Supporting information for this article is available online at
http://dx.doi.org/10.1055/s-0035-1561953.
S
u
p
p
ortiInfogrmoaitn
S
u
p
p
o
nrtogI
f
rmoaitn
1H NMR: δ = 0.14 (s, 9 H), 2.74 (t, J = 5.2 Hz, 3 H), 3.08 (t, J = 5.2 Hz, 2
H), 3.93 (t, J = 5.2 Hz, 2 H), 9.43 (br s, 2 H).
References
13C NMR: δ = –0.5, 33.3, 50.6, 57.7.
(1) New address: K. Herasymchuk, Department of Chemistry,
Simon Fraser University, 8888 University Drive, Burnaby BC V5A
1S6 Canada.
(2) Undergraduate research participant.
© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–I

H
K. Herasymchuk et al.
Paper
Synthesis
(3) (a) Chase, P. A.; Gossage, R. A.; van Koten, G. Top. Organomet.
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Synthesis
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© Georg Thieme Verlag Stuttgart · New York — Synthesis 2016, 48, A–I