Iron-Catalyzed C(sp 2)-C(sp 3) Cross-Coupling Reactions of Di(hetero)arylmanganese Reagents and Primary and Secondary Alkyl Halides

Article abstract of DOI:10.1055/s-0036-1590891

An iron-catalyzed cross-coupling between di(hetero)arylmanganese reagents and primary and secondary alkyl halides is reported. No rearrangement of secondary alkyl halides to unbranched products was observed in these C-C bond-forming reactions.

Full text of DOI:10.1055/s-0036-1590891

SYNLETT
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-
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0
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©
Georg Thieme Verlag Stuttgart · New York
2017, 28, A–F
letter
A
en
Synlett
M. S. Hofmayer et al.
Letter
2
3
Iron-Catalyzed C(sp )–C(sp ) Cross-Coupling Reactions of Di(hete-
ro)arylmanganese Reagents and Primary and Secondary Alkyl Ha-
lides
Maximilian S. Hofmayera
Jeffrey M. Hammanna
Gérard Cahiezb
F
F
O
O
20% FeCl2, THF
NC
Mn
2
NC
+
–20 to 25 °C, 16 h
I
Paul Knochel*a
0
0
0
0
0-
0
0
1
7-
9
1
3
4-
3
3
2
(0.7 equiv)
86% yield
a
Department of Chemistry, Ludwig-Maximilians-Universität
München, Butenandtstraße 5–13, Haus F, 81377 München,
Germany
20 examples
up to 88% yield
Paul.Knochel@cup.uni-muenchen.de
Institut de Recherche de Chimie Paris, CNRS, Chimie ParisTech,
b
1
1 Rue Pierre et Marie Curie, 75005 Paris, France
Received: 04.07.2017
Accepted after revision: 03.08.2017
Published online: 30.08.2017
(L3, L4), phenanthroline (L5, L6) and NHC ligands (L7), as
well as isoquinoline (L8) and 4-fluorostyrene (L9), which
were beneficial ligands in previous studies,8 did not im-
prove the reaction outcome (Table 1, entries 5–13). Re-
markably, CrCl and NiBr were inefficient catalysts for this
DOI: 10.1055/s-0036-1590891; Art ID: st-2017-b0542-l
Abstract An iron-catalyzed cross-coupling between di(hetero)aryl-
manganese reagents and primary and secondary alkyl halides is report-
ed. No rearrangement of secondary alkyl halides to unbranched prod-
ucts was observed in these C–C bond-forming reactions.
2
2
reaction (Table 1, entries 14 and 15). A solvent screening
showed that THF led to the best reaction outcome com-
9
pared to NMP, DME, 1,4-dioxane, and tBuOMe. Thus, di(p-
Key words iron, catalysis, cross-coupling, manganese, alkyl halides
anisyl)manganese (2a) reacted in the presence of 20 mol%
FeCl in THF at –20 to 25 °C (16 h) to produce the substitu-
2
Transition-metal-catalyzed cross-coupling reactions
tion product 3a in 69% yield (Table 1, entry 4).
have found broad application, especially for the synthesis of
1
agrochemicals and pharmaceuticals. In the past, palladium
Table 1 Reaction Conditions Optimization of the Cross-Coupling of
Bromocyclohexane (1a) with the Di(p-anisyl)manganese Reagent (2a)
and nickel complexes have frequently been used for such
2
couplings. However, the high price as well as toxicity is-
3
sues of these catalysts led to the search for alternative
Mn
2
catalyst (20 mol%)
transition metals for cross-coupling reactions. Especially,
iron is a cheap and environmentally benign alternative for
C–C bond-forming reactions, due to its high abundance in
the earth’s crust. Pioneering work by Fürstner, Cahiez, as
well as other research groups demonstrated the high po-
+
additive (40
mol%)
MeO
Br
MeO
1a
THF, –20 to
3a
2a
0.7 equiv)
25 °C, 16 h
(
4
5
6
Yield (%)a
Entry
Catalyst
Additive
tential of iron salts as catalysts in coupling reactions. How-
ever, most of these reactions use magnesium organometal-
lics as nucleophiles, which are not always the best choice
due to their high nucleophilicity. In contrast, the use of or-
ganomanganese reagents enables performing coupling re-
actions under mild conditions.
Recently, we have demonstrated that cobalt(II) chloride
is an excellent catalyst for the cross-coupling of diarylman-
ganese reagents with secondary alkyl halides.7 However,
some of these coupling reactions were not very efficient
and gave only poor yields (Table 1, entry 1). Thus, the cross-
coupling between cyclohexyl bromide (1a) and di(p-ani-
1
2
3
4
5
6
7
8
9
CoCl
Fe(acac)
Fe(acac)3
2
–
28
64
2
–
–
66
69 (63b)
FeCl
FeCl
FeCl
2
2
2
–
L1
L2
L3
L4
L5
L6
L7
L8
L9
64
56
66
62
62
63
58
56
54
FeCl2
FeCl
2
FeCl2
10
11
12
13
FeCl
FeCl
FeCl
FeCl
2
2
2
2
syl)manganese (2a, 0.7 equiv) using 20 mol% CoCl gave the
2
desired product 3a in only 28% yield. In contrast, different
iron salts proved to be more efficient and furnished 3a in
better yields (64–69%, Table 1, entries 2–4). FeCl gave the
2
best results. The addition of amine- (L1, L2), phosphine-
©
Georg Thieme Verlag Stuttgart · New York — Synlett 2017, 28, A–F

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Synlett
M. S. Hofmayer et al.
Letter
Table 1 (continued)
Entry
Table 2 Iron-Catalyzed Cross-Coupling Reactions between Various Al-
kyl Halides of Type 1 and the Diarylmanganese 2a Producing Coupling
Products of Type 3
Catalyst
CrCl
Additive Yield (%)a
1
4
5
2
–
–
0
5
1
NiBr
2
Mn
2
20% FeCl2, THF
+
NMe2
NMe2
X
–20 to 25 °C, 16 h
NMe2
2
Ph P
MeO
Me2N
PPh2
MeO
2a
0.7 equiv)
1
3
(
X = Br, I
L1
L2
L3
Entry Electrophile
Product
Yield (%)
Me Me
Ph
Ph
3
2a (1b X = Cl)
O
N
N
1
63 (1a X = Br)
73 (1c X = I)
N
N
Me
Me
PPh2
PPh2
X
MeO
L4
L5
L6
1
a–c
3a
Cl
iPr
iPr
Me
Me
51b
N
N
2
3
N
I
F
Me
Me
MeO
iPr
iPr
1
d
3b
L7
L8
L9
a
OTBS
Calibrated GC yield using undecane as internal standard.
Isolated yield.
b
OTBS
66c
I
MeO
These optimized conditions proved to be general, and
1
e
3c
the cross-coupling of di(p-anisyl)manganese (2a) with vari-
ous primary and secondary alkyl halides of type 1 were
successfully performed (Table 2). Thus, a range of cycloalkyl
halides were readily employed in this reaction. Cyclohexyl
chloride (1b), bromide (1a), and iodide (1c) underwent the
cross-coupling with 2a to afford the desired product 3a in
2–73% yield (Table 2, entry 1). The secondary bromides
and iodides 1d–h bearing an iPr, OTBS, or a tBu group were
also tolerated, leading to the substitution products 3b–e in
tBu
tBu
d
4
3 (1f X = Br)
4
5
e
70 (1g X = I)
X
MeO
1
f–g X = Br, I
3d
3
88
4
3–88% yield (Table 2, entries 2–5).
I
Furthermore, the functionalized acyclic secondary alkyl
MeO
iodides 1i–k, bearing a CF , OTBS, or a fluoro substituent,
3
1
h
3e
proved to be good substrates, affording the alkylated prod-
ucts 3f–h in 44–58% yield (Table 2, entries 6–8). Interest-
ingly, no rearrangement of branched secondary alkyl
groups to the corresponding unbranched secondary alkyl
moiety was observed. Additionally, the primary alkyl iodide
Me
Me
6
7
CF52
I
CF3
MeO
1
i
j
3f
(
3-iodopropyl)benzene (1l) coupled smoothly, affording 3i
in 46% yield (Table 2, entry 9).
Me
Me
OTBS
44
I
OTBS
MeO
1
3g
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Georg Thieme Verlag Stuttgart · New York — Synlett 2017, 28, A–F

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M. S. Hofmayer et al.
Letter
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6–62% yield (Table 3, entries 1 and 2). Interestingly, the di-
Entry Electrophile
Product
Yield (%)
58
arylmanganese 2c bearing an OBoc group was cross-cou-
pled with 1h, leading to the desired product 3l in 56% yield
F
Me
F
Me
(Table 3, entry 3). The coupling of the electron-poor diaryl-
8
I
manganese 2d,e with the alkyl halides 1n,o afforded the
cross-coupling products 3m–o in 48–78% yield (Table 3,
entries 4–6). Also, the diarylmanganese 2f was successfully
coupled with the secondary alkyl iodide 1j, to give the de-
sired product 3p in 80% yield (Table 3, entry 7). Additional-
ly, heterocyclic diarylmanganese reagents were compatible
under these conditions, leading to the expected heterocy-
cles in good yields. Thus, the di(thiophene-3-yl)manganese
(2g) coupled smoothly with 1p or 1m providing the arylat-
ed thiophenes in 82–87% yield (Table 3, entry 8). Moreover,
diarylmanganese generated via directed manganation using
MeO
1
k
l
3h
Ph
9
I
Ph
46
MeO
1
3i
a
b
c
Calibrated GC yield using undecane as internal standard.
Electrophile: cis/trans ratio: 99:1; product: cis/trans ratio: 83:17.
Electrophile: cis/trans ratio: 99:1; product: cis/trans ratio: 75:25.
Electrophile: cis/trans ratio: 75:25; product: cis/trans ratio: 98:2.
Electrophile: cis/trans ratio: 99:1; product: cis/trans ratio: 60:40.
d
e
10
TMP Mn·2MgCl ·4LiCl (0.7 equiv) could also be readily
2
2
employed, leading to the corresponding products in 46–86%
yield (Table 3, entries 9 and 10). For the coupling of the dia-
rylmanganese 2h an excellent diastereoselectivity in the
coupling reaction was observed (dr = 99:1).
Furthermore, a range of functionalized diarylmanga-
nese reagents could also be used in this reaction (Table 3).
p-MOMO-C H ) Mn (2b) reacted smoothly with the alkyl
(
6
4 2
iodides 1i and 1m, leading to the expected products 3j,k in
Table 3 Iron-Catalyzed Cross-Couplings of Various Diaryl- and Diheteroarylmanganese Reagents of Type 2 with Secondary Alkyl Iodides of Type 1
Leading to Products of Type 3
R2
Mn
2
R2
20% FeCl , THF
2
R1
+
R3
R3 –20 to 25 °C, 16 h
R1
I
X
X
2
(0.7 equiv)
1
3
X = C, N, S
Entry
1
Manganese reagent
Electrophile
Product
Yield (%)
46
Me
Mn
2
Me
CF3
I
CF3
MOMO
MOMO
2
b
1i
3j
NBoc
Mn
2
NBoc
2
3
62
56
I
MOMO
MOMO
2
b
1m
3k
BocO
Mn
2
BocO
I
2
c
1h
3l
Cl
Me
Mn
2
Cl
Me
4
57
NC
I
NC
2
d
1n
3m
©
Georg Thieme Verlag Stuttgart · New York — Synlett 2017, 28, A–F

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M. S. Hofmayer et al.
Letter
Table 3 (continued)
Entry
Manganese reagent
Electrophile
Product
Yield (%)
Me
Me
Me
Me
Mn
2
5
I
48
NC
OMe
NC
OMe
2
d
1o
I
3n
Me
Mn
2
6
7
8
78
F3C
OMe
F3C
OMe
2
e
1o
3o
Mn
2
Me
OTBS
80
Ph
I
OTBS
Ph
F
F
2
f
1j
3p
NBoc
Mn
2
NBoc
8
8
2 (using 1p)
7 (using 1m)
S
X
S
2
g
1p X = Br, 1m X = I
3q
TBSO
Mn
2
TBSO
NTs
I
NTs
9
N
46 dr = 99:1
CN
N
Cl
CN
Cl
2
h
1q dr = 99:1
3r
F
F
O
O
NC
Mn
2
NC
10
86
I
2
i
1r
3s
In summary, we have developed an iron-catalyzed
cross-coupling reaction of di(hetero)arylmanganese deriva-
P. Knochel and G. Cahiez for financial support. We also thank Albe-
marle (Hoechst, Germany) for the generous gift of chemicals. M.S.H.
thanks the Richard-Winter-foundation for a fellowship.
tives with secondary alkyl halides using FeCl as a catalyst,
2
which leads to the coupling products in up to 88% yield.
High diastereoselectivities can be reached in these coupling
reactions (dr up to 99:1). Remarkably, rearrangement of
secondary alkyl halides to the corresponding unbranched
products was not observed in these C–C forming reactions.
Further investigations on this promising cross-coupling are
Supporting Information
Supporting information for this article is available online at
https://doi.org/10.1055/s-0036-1590891.
S
u
p
p
ortioIgnfrm oaitn
S
u
p
p
o
nrtogI
i
f
rm oaitn
11,12
currently under way in our laboratories.
References and Notes
(
1) (a) Cross-Coupling Reactions. A Practical Guide; Miyaura, N., Ed.;
Acknowledgment
Springer: Berlin, 2002. (b) Metal-Catalyzed Cross-Coupling Reac-
tions; Diederich, F.; de Meijere, A., Eds.; Wiley-VCH: Weinheim,
We thank the DFG (SFB 749), the LMU Munich, and the International
Associated Laboratory IrMaCaR between the research groups of
2004. (c) Modern Drug Synthesis; Li, J. J.; Johnson, D. S., Eds.;
©
Georg Thieme Verlag Stuttgart · New York — Synlett 2017, 28, A–F

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M. S. Hofmayer et al.
Letter
Wiley-VCH: Weinheim, 2010. (d) Organotransition Metal Chem-
istry; Hartwig, J. F., Ed.; University Science Books: Sausalito, CA,
(8) (a) Korn, T. J.; Knochel, P. Angew. Chem. Int. Ed. 2005, 44, 2947.
(b) Korn, T. J.; Schade, M. A.; Cheemala, M. N.; Wirth, S.;
Guevara, S. A.; Cahiez, G.; Knochel, P. Synthesis 2006, 3547.
(c) Korn, T. J.; Schade, M. A.; Wirth, S.; Knochel, P. Org. Lett.
2006, 8, 725. (d) Wunderlich, S. H.; Knochel, P. Angew. Chem. Int.
Ed. 2009, 48, 9717. (e) Steib, A. K.; Thaler, T.; Komeyama, K.;
Mayer, P.; Knochel, P. Angew. Chem. Int. Ed. 2011, 50, 3303.
(f) Kuzmina, O. M.; Steib, A. K.; Markiewicz, J. T.; Flubacher, D.;
Knochel, P. Angew. Chem. Int. Ed. 2013, 52, 4945. (g) Kuzmina, O.
M.; Steib, A. K.; Fernandez, S.; Boudot, W.; Markiewicz, J. T.;
Knochel, P. Chem. Eur. J. 2015, 21, 8242. (h) Benischke, A. D.;
Knoll, I.; Rerat, A.; Gosmini, C.; Knochel, P. Chem. Commun.
2016, 52, 3171.
(9) For detailed information, see the Supporting Information.
(10) Wunderlich, S. H.; Kienle, M.; Knochel, P. Angew. Chem. Int. Ed.
2009, 48, 7256.
(11) Starting materials were prepared according to literature proce-
dures with only little deviation: Cheung, C. W.; Ren, P.; Hu, X.
Org. Lett. 2014, 16, 2566.
2010.
(
2) FeCl ca. 375 €/mol, PdCl ca. 4500 €/mol; prices retrieved from
2
2
Alfa Aesar in May 2017.
(
3) (a) LD50(FeCl , rat oral) = 900 mg/kg; LD (NiCl , rat oral) = 186
2
50
2
mg/kg). (b) Egorova, K. S.; Ananikov, V. P. Angew. Chem. Int. Ed.
016, 55, 12150.
2
(
4) For selected examples, see: (a) Fürstner, A.; Brunner, H. Tetrahe-
dron Lett. 1996, 37, 7009. (b) Fürstner, A.; Leitner, A. Angew.
Chem. Int. Ed. 2002, 41, 609. (c) Fürstner, A.; Leitner, A.;
Méndez, M.; Krause, H. J. Am. Chem. Soc. 2002, 124, 13856.
(
(
d) Martin, R.; Fürstner, A. Angew. Chem. Int. Ed. 2004, 43, 3955.
e) Scheiper, B.; Bonnekessel, M.; Krause, H.; Fürstner, A. J. Org.
Chem. 2004, 69, 3943. (f) Sherry, B. D.; Fürstner, A. Acc. Chem.
Res. 2008, 41, 1500. (g) Sun, C.-L.; Krause, H.; Fürstner, A. Adv.
Synth. Catal. 2014, 356, 1281. (h) Casitas, A.; Krause, H.;
Goddard, R.; Fürstner, A. Angew. Chem. Int. Ed. 2015, 54, 1521.
(i) Fürstner, A. ACS Cent. Sci. 2016, 2, 778.
(
5) For selected examples, see: (a) Cahiez, G.; Avedissian, H. Synthe-
sis 1998, 1199. (b) Duplais, C.; Bures, F.; Sapountzis, I.; Korn, T.
J.; Cahiez, G.; Knochel, P. Angew. Chem. Int. Ed. 2004, 43, 2968.
(12) Typical Procedure for the Iron-Catalyzed Cross-Coupling of
Di(hetero)arylmanganese Reagents with Alkyl Halides
A dry and argon-flushed 20 mL Schlenk tube, equipped with a
stirring bar and a septum, was charged with anhydrous FeCl2
(25 mg, 0.20 mmol, 20 mol%). The alkyl halide (1 mmol, 1.0
equiv) in THF (1 mL) was added, and the mixture was cooled to
–20 °C. The di(hetero)arylmanganese reagent (0.7 mmol, 0.7
equiv) was added dropwise, and the mixture was allowed to
(c) Cahiez, G.; Chaboche, C.; Mahuteau-Betzer, F.; Ahr, M. Org.
Lett. 2005, 7, 1943. (d) Cahiez, G.; Duplais, C.; Moyeux, A. Org.
Lett. 2007, 9, 3253. (e) Cahiez, G.; Habiak, V.; Duplais, C.;
Moyeux, A. Angew. Chem. Int. Ed. 2007, 46, 4364. (f) Cahiez, G.;
Moyeux, A.; Buendia, J.; Duplais, C. J. Am. Chem. Soc. 2007, 129,
1
(
2
3788. (g) Cahiez, G.; Gager, O.; Habiak, V. Synthesis 2008, 2636.
h) Cahiez, G.; Foulgoc, L.; Moyeux, A. Angew. Chem. Int. Ed.
009, 48, 2969. (i) Benischke, A. D.; Breuillac, A. J. A.; Moyeux,
warm to r.t. overnight. A sat. aq solution of NH Cl (5 mL) and
4
EtOAc (5 mL) were added, the phases were separated, and the
aqueous phase was extracted with EtOAc (3 × 20 mL). The com-
bined organic phases were washed with brine, dried over
Na SO , and the solvents were evaporated. The residue was sub-
A.; Cahiez, G.; Knochel, P. Synlett 2016, 27, 471.
(
6) For selected examples, see: (a) Nakamura, M.; Matsuo, K.; Ito, S.;
Nakamura, E. J. Am. Chem. Soc. 2004, 126, 3686. (b) Nakamura,
M.; Ito, S.; Matsuo, K.; Nakamura, E. Synlett 2005, 1794.
2
4
jected to column chromatography purification (SiO ; i-hex-
2
ane/EtOAc) yielding the corresponding title compound.
(c) Hatakeyama, T.; Nakamura, M. J. Am. Chem. Soc. 2007, 129,
1-(3-Isopropylcyclohexyl)-4-methoxybenzene (3b)
9
844. (d) Hatakeyama, T.; Yoshimoto, Y.; Gabriel, T.; Nakamura,
Following the typical procedure, 1d (252 mg, 1.0 mmol, 1.0
equiv, in 1 mL THF) reacts with di(p-anisyl)manganese (2a, 0.7
mmol, 0.7 equiv) at –20 °C. The solution was allowed to warm
to r.t., was stirred for 16 h, and was worked up as usual. The
crude product was purified by column chromatography on
silica using i-hexane/EtOAc (100:2) as an eluent to afford 3b as a
M. Org. Lett. 2008, 10, 5341. (e) Ito, S.; Fujiwara, Y.-I.; Nakamura,
E.; Nakamura, M. Org. Lett. 2009, 11, 4306. (f) Noda, D.; Sunada,
Y.; Hatakeyama, T.; Nakamura, M.; Nagashima, H. J. Am. Chem.
Soc. 2009, 131, 6078. (g) Hatakeyama, T.; Hashimoto, T.; Kondo,
Y.; Fujiwara, Y.; Seike, H.; Takaya, H.; Tamada, Y.; Ono, T.;
Nakamura, M. J. Am. Chem. Soc. 2010, 132, 10674. (h) Nakamura,
E.; Yoshikai, N. J. Org. Chem. 2010, 75, 6061. (i) Liu, Z.-Q.; Zhang,
Y.; Zhao, L.; Li, Z.; Wang, J.; Li, H.; Wu, L.-M. Org. Lett. 2011, 13,
1
colorless oil (51%, 119 mg, 0.51 mmol, dr = 83:17). H NMR (400
MHz, CDCl ): δ = 7.19–7.12 (m, 2 H), 6.90–6.83 (m, 2 H), 3.80 (s,
3
3 H), 2.48 (tt, J = 11.7, 3.4 Hz, 1 H), 1.95–1.81 (m, 3 H), 1.76 (dtt,
J = 11.6, 3.4, 1.8 Hz, 1 H), 1.54–1.33 (m, 3 H), 1.33–1.21 (m, 2 H),
1.12 (dt, J = 12.8, 11.8 Hz, 1 H), 0.90 (dd, J = 6.8, 3.7 Hz, 6 H)
2208. (j) Kuzmina, O. M.; Steib, A. K.; Flubacher, D.; Knochel, P.
Org. Lett. 2012, 14, 4818. (k) Lin, Y.-Y.; Wang, Y.-J.; Lin, C.-H.;
Cheng, J.-H.; Lee, C.-F. J. Org. Chem. 2012, 77, 6100. (l) Shang, R.;
Ilies, L.; Matsumoto, A.; Nakamura, E. J. Am. Chem. Soc. 2013,
13
ppm. C NMR (101 MHz, CDCl ): δ = 157.8, 140.5, 127.8, 113.8,
3
55.4, 44.6, 44.0, 38.4, 34.7, 33.2, 29.5, 27.0, 20.0, 19.9 ppm. FTIR
(ATR): 2954, 2922, 2852, 1512, 1462, 1444, 1244, 1176, 1038,
135, 6030. (m) Nakamura, E.; Hatakeyama, T.; Ito, S.; Ishizuka,
–1
K.; Ilies, L.; Nakamura, M. Org. React. 2014, 83, 1. (n) Agrawal, T.;
Cook, S. P. Org. Lett. 2014, 16, 5080. (o) Kuzmina, O. M.; Steib, A.
K.; Moyeux, A.; Cahiez, G.; Knochel, P. Synthesis 2015, 47, 1696.
824, 806 cm . MS (EI, 70 eV): m/z (%) = 232 (55), 189 (78), 147
(100), 134 (68), 121 (77). HRMS (EI, 70 eV): m/z calcd for
[C16H24O]: 232.1827; found: 232.1821.
(
p) Shang, X.; Liu, Z.-Q. Synthesis 2015, 47, 1706. (q) Agata, R.;
tert-Butyl{3-[2-fluoro-(1,1′-biphenyl)-4-yl]butoxy}dimeth-
ylsilane (3p)
Iwamoto, T.; Nakagawa, N.; Isozaki, K.; Hatakeyama, T.; Takaya,
H.; Nakamura, M. Synthesis 2015, 47, 1733. (r) Bauer, I.; Knölker,
H.-J. Chem. Rev. 2015, 115, 3170. (s) Greiner, R.; Blanc, R.;
Petermayer, C.; Karaghiosoff, K.; Knochel, P. Synlett 2016, 27,
Following the typical procedure, tert-butyl(3-iodobu-
toxy)dimethylsilane (1j, 314 mg, 1.0 mmol, 1.0 equiv, in
1 mL THF) reacts with 2f (0.7 mmol, 0.7 equiv) at –20 °C. The
solution was allowed to warm to r.t., was stirred for 16 h, and
was worked up as usual. The crude product was purified by
column chromatography on silica using i-hexane/EtOAc (100:4)
2
31. (t) Halli, J.; Schneider, A. E.; Beisel, T.; Kramer, P.; Shemet,
A.; Manolikakes, G. Synthesis 2017, 49, 849. (u) Parchomyk, T.;
Koszinowski, K. Synthesis 2017, 49, 3269.
(
7) Hofmayer, M. S.; Hammann, J. M.; Haas, D.; Knochel, P. Org. Lett.
as an eluent to afford 3p as colorless oil (80%, 288 mg, 0.80
1
2016, 18, 6456.
mmol). H NMR (600 MHz, CDCl ): δ = 7.57–7.54 (m, 2 H), 7.46–
3
7.42 (m, 2 H), 7.38–7.34 (m, 2 H), 7.05 (dd, J = 7.8, 1.7 Hz, 1 H),
©
Georg Thieme Verlag Stuttgart · New York — Synlett 2017, 28, A–F

F
Synlett
M. S. Hofmayer et al.
Letter
7
(
6
.00 (dd, J = 12.0, 1.7 Hz, 1 H), 3.59 (dt, J = 10.2, 6.2 Hz, 1 H), 3.52
dt, J = 10.2, 6.7 Hz, 1 H), 2.95 (h, J = 7.1 Hz, 1 H), 1.82 (dt, J = 7.1,
.3 Hz, 2 H), 1.29 (d, J = 7.0 Hz, 3 H), 0.90 (s, 9 H), 0.03 (d, J = 1.5
26.1, 22.2, 18.4, –5.2 ppm. FTIR (ATR): 2956, 2928, 2856, 1484,
1472, 1462, 1418, 1254, 1098, 1076, 1010, 980, 900, 870, 832,
–1
810, 774, 766, 724, 696 cm . MS (EI, 70 eV): m/z (%) = 302 (22),
301 (100), 207 (22), 179 (77), 165 (35). HRMS (EI, 70 eV): m/z
13
Hz, 6 H) ppm. C NMR (150 MHz, CDCl ): δ =159.9 (d, J = 247.4
Hz), 149.3 (d, J = 6.7 Hz), 136.1, 130.6, 129.1, 128.5, 127.5, 126.5
3
+
+
calcd for [C21H28FOSi ]: 343.1888; found: 343.1872 [M – CH ].
3
(d, J = 13.4 Hz), 123.3, 114.7 (d, J = 22.6 Hz), 61.1, 41.1, 35.9,
©
Georg Thieme Verlag Stuttgart · New York — Synlett 2017, 28, A–F