Amide-controlled highly selective catalytic borylcupration of allenes

Article abstract of DOI:10.1002/chem.201202835

A novel copper-catalyzed, highly regio- and stereoselective borylcupration of substituted 2,3-allenamides with bis(pinacolato)diboron producing Z-β-borylated β,γ-unsaturated enoamides has been demonstrated. Due to the unique effect of the amide-group, perfect regio- and stereoselectivity and good to excellent yields have been achieved, which were rationalized by a DFT study. Perfect selection! A copper-catalyzed, highly regio- and stereoselective borylcupration of 2,3-allenamide with bis(pinacolato)diboron producing Z-β-borylated β,γ-unsaturated amides has been developed (see scheme; L=large, S=small). Due to the unique effect of the amide group, perfect regio- and stereoselectivity and good to excellent yields have been achieved. The results have been rationalized by a DFT study. Copyright

Full text of DOI:10.1002/chem.201202835

FULL PAPER
DOI: 10.1002/chem.201202835
Amide-Controlled Highly Selective Catalytic Borylcupration of Allenes
Weiming Yuan,[a] Xue Zhang,*[b] Yihua Yu,[c] and Shengming Ma*[a, b]
Abstract: A novel copper-catalyzed, highly regio- and stereoselective borylcupra-
tion of substituted 2,3-allenamides with bis(pinacolato)diboron producing Z-b-
borylated b,g-unsaturated enoamides has been demonstrated. Due to the unique
effect of the amide-group, perfect regio- and stereoselectivity and good to excel-
lent yields have been achieved, which were rationalized by a DFT study.
Keywords: allenes · amides · boron ·
copper · regioselectivity · stereo-
AHCTUNGTRENNGsUN electivity
Introduction
Organoboranes are a class of highly useful intermediates
that are widely used in organic synthesis because of their
potential use in the construction of complex molecules.[1–4]
In addition to the traditional hydroboration of terminal al-
kenes and alkynes with boranes,[5] much attention has been
paid to the synthesis of organoboranes from the Cu-cata-
lyzed borylcupration of unsaturated hydrocarbons with bis-
ACHTUNGTRENNUNG
CTHUNGTRENNUNG
fording stereodefined 1-alkenyl boronates.[6] The challenge
for such syntheses remains the limited range of substrates
that allow control of regioselectivity and inclusion of syn-
thetically attractive functional groups. For the Cu-catalyzed
borylcupration reaction of multisubstituted allenes, a formi-
dable challenge is to control the regio- and stereoselectivity
because, in principle, it is possible to produce eight regio-
and stereoisomers (Scheme 1). In 2011, Santos and co-work-
ers first reported the copper-catalyzed b-borylation of alle-
noates by using a preactivated diboron reagent (PDIPA=pi-
nacolato diisopropanolaminato diboron) and CF3CH2OH as
proton source, albeit with a limited substrate scope and low
Scheme 1. Challenges for the hydroboration of multisubstituted allenes.
to moderate yields (Scheme 2a).[12] We developed highly
regio- and stereoselective copper-catalyzed borylcuprations
of aryl-substituted allenes with bis(pinacolato)diboron to
produce 2-alken-2-yl boronates as the only product with ex-
clusive Z geometry in the presence of tris(p-methoxy-
AHCTUNGTREGpNNNU henyl)phosphine as ligand. When the bidentate phosphine,
[a] W. Yuan, Prof. Dr. S. Ma
2,2’-bis(diphenylphosphino)biphenyl (BIPHEP), was used,
the regioselectivity switched; alkyl, benzyl, or aryl-substitut-
ed allenes all afforded the 1-alken-2-yl boronates highly se-
lectively (Scheme 2b).[13] Hoveyda and co-workers reported
the hydroboration of a specific substrate, 4-(o-methoxyphe-
Shanghai Key Laboratory of Green Chemistry and Chemical Process
Department of Chemistry, East China Normal University
3663 North Zhongshan Lu, Shanghai 200062 (P. R. China)
Fax : (+86)21-62609305
E-mail: masm@sioc.ac.cn
[b] Dr. X. Zhang, Prof. Dr. S. Ma
AHCTUNGTREGnNNNU yl)-1,2,5-hexatriene, by using a NHC–Cu complex as cata-
State Key Laboratory of Organometallic Chemistry
Shanghai Institute of Organic Chemistry
Chinese Academy of Sciences
345 Lingling Lu, Shanghai 200032 (P. R. China)
E-mail: xzhang@sioc.ac.cn
lyst with a regioselectivity of 9:1 (Scheme 1c).[14] It should
be noted that moisture- and air-sensitive NaOtBu was used
as base in these two reactions.[13,14] Thus, there are some
challenges that require further attention. Here, we wish to
report our recent observation that by introducing a very
common and synthetically attractive directing functional
group, i.e., amide, the issues of regio- and stereoselectivity
of borylcupration of allenes have been addressed under
mild conditions with K2CO3 as base, producing useful
[c] Dr. Y. Yu
Shanghai Key Laboratory of Magnetic Resonance
Department of Physics, East China Normal University
3663 North Zhongshan Lu, Shanghai 200062 (P. R. China)
Supporting information for this article is available on the WWW
under http://dx.doi.org/10.1002/chem.201202835.
Chem. Eur. J. 2013, 19, 7193 – 7202
ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
7193

substituted vinylboronates Z-2
exclusively in good to excellent
yields (Table 2, entries 1–8);
with R1 being an iso-alkyl
group (entries 4–7) or a longer
carbon chain (entry 8), the
yields were somewhat lower.
The reaction of 4-benzyl-substi-
tuted allenamide 1h also pro-
duced Z-2h in good yield
(entry 9); R1 or R2 may also be
an aryl- or heteroaryl group
(entries 10–13). For 2-unsubsti-
tuted 2,3-pentadienamide 1m,
the Z/E selectivity was lower.
After screening, it was observed
that the reaction in THF afford-
ed the product Z-2m in 90%
yield with a high regio- and
stereoselectivity (entry 15). The
geometry of the remaining C=C
bond in 2d and 2g was deter-
mined to be Z, based on
NOESY experiments. In addi-
tion, the reaction of 1d pro-
Scheme 2. Previous reports and the new approach.
ceeded smoothly to afford Z-2d
on a one gram scale in 86%
yield (entry 5).
Z-alkenyl boronates containing an amide functional group
exclusively by applying P(p-MeOC6H4)3 as the ligand
(Scheme 2d).
The borylcupration of 4,4-disubstituted allenamides also
proceeded smoothly in almost quantitative yields irrespec-
tive of whether the N-protecting group was Bn, Ph, or nBu
(Scheme 3). Even for 4-methyl-4-tert-butyl- or 4-methyl-4-
phenyl-substituted allenamides 1q and 1r, the reaction af-
forded the corresponding products Z-2q and Z-2r as the
only isomer in good yields. The structure of Z-2q was fur-
Results and Discussion
After numerous trials with allenyl ketones, carboxylic acids,
and esters, we started to observe some interesting results
with 2,3-allenamide 1a. Firstly, we observed that although
the CuCl-catalyzed reaction with triphenyl phosphine as the
ligand did not proceed (Table 1, entry 1), when 20 mol%
K3PO4 was added, to our delight, the reaction afforded 2a
in 85% yield with Z-geometry exclusively at room tempera-
ture (Table 1, entry 2); the reaction with K2CO3 afforded
similar results (Table 1, entry 3). The use of other bases did
not lead to any further improvement in the results (Table 1,
entries 4 and 5). Furthermore, it was exciting to observe that
by increasing the electron-donating ability of the applied
ligand, the reaction proceeded much faster and afforded the
product Z-2a in higher yields (Table 1, entries 6–8); the use
of K2CO3 (5 mol%) was sufficient for such a transformation,
although a longer reaction time (8 h) was required (Table 1,
entry 9). Thus, we chose 5 mol% CuCl, 6 mol%
P(p-MeOC6H4)3, 20 mol% K2CO3, and 2 equivalents of
iPrOH in Et2O at room temperature as the standard condi-
tions for the borylcupration reaction.
Table 1. Optimization of reaction conditions for copper-catalyzed regio-
and stereoselective borylcupration of 2,3-allenamides.
Entry
Base
Ligand
t [h]
Yield Z-2a [%][a]
1
2
3
4
5
6
7
8
9
–
PPh3
PPh3
PPh3
PPh3
PPh3
P(p-MeOC6H4)3
TFP
11
2.5
2.5
7
11
2.5
2
0
85
K3PO4
K2CO3
NaOAc
Na2CO3
K2CO3
K2CO3
K2CO3
83
84 (4)[b]
75 (20)[b]
91
90
91
89
P
A
2
8
[c]
K2CO3
[a] The starting material 1a was converted completely, and the yield of
Z-2a was determined by 1H NMR spectroscopic analysis using 1,3,5-tri-
methylbenzene as internal standard. [b] The amount of recovered starting
material is given in parentheses. [c] K2CO3 (5 mol%) was added. TFP=
With the optimized conditions in hand, we observed that
different 2,4-dialkyl-substituted allenamides afforded the tri-
triACHTUNGTNER(NNUG 2-furyl)phosphine. PACHTUNRTEGN(GNUN o-tol)3 =triACHTUNGTREN(NNGU o-tolyl)phosphine.
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Borylcupration of Allenes
FULL PAPER
Table 2. CuCl-catalyzed addition of bis(pinacolato)diboron to 2,4-disub-
stituted 2,3-allenamides.
ther confirmed by X-ray single-crystal diffraction studies
(Figure 1).[15]
Finally, the reaction could also be extended to 2,4,4-tri-
substituted allenamide 1s, affording 2s in 87% yield
[Eq. (1)].
Entry[a] R1
R2
1
t
Yield
2
[h] [%][b]
1
2
3
4
Me
Et
n-Pr
iPr
iPr
nBu
nBu
nBu
nBu
nBu
nBu
nBu
nC8H17
nBu
Me
1a
1b
1c
1d
1d
1e
1 f
1g
1h
1i
2
2
2
3
94
92
90
87
Z-2a
Z-2b
Z-2c
Z-2d
Z-2d
Z-2e
Z-2 f
Z-2g
Z-2h
Z-2i
Z-2j
Z-2k
Z-2l
Z-2m/E-2m
Z-2m
5[c]
6
2.5 86
3 86
2.5 84
2.5 86
2
2
2
2
2
2
In contrast, 2,4-disubstituted 2,3-allenoate or 1,3-disubsti-
tuted phenyl-1,2-decadiene afforded a mixture with poor
regioselectivity[16] (Scheme 4), indicating the importance of
the amide group.
iBu
7
8
9
10
11
12
13
cyclohexyl
nC5H11
Bn
87
77
82
64
Ph
p-MeOC6H4 nC8H17
2-thenyl
Me
Me
Me
1j
1k
nBu
p-MeC6H4 1l
H
H
67
14
1m
54[d]
15[e]
1m 2.5 90
[a] Reaction conditions: 2,3-allenamide 1 (0.5 mmol), bis(pinacolato)di-
boron (0.6 mmol), CuCl (5 mol%), P(p-MeOC6H4)3 (6 mol%), K2CO3
(20 mol%), iPrOH (1.0 mmol), Et2O (2 mL), RT. [b] Yield upon isola-
tion. [c] The reaction was carried out on a one gram scale. [d] The yield
was determined by 1H NMR spectroscopic analysis using 1,3,5-trimethyl-
benzene as internal standard and Z-2m/E-2m=83:17. [e] THF was used
as solvent.
Scheme 4. Borylcupration of 2,4-disubstituted 2,3-allenoate or 1,3-disub-
stituted phenyl-1,2-decadiene.
To demonstrate the utility of the highly regio- and stereo-
selective borylcupration reaction, halogenation of Z-2d was
attempted by using CuCl2 or CuBr2 to produce the corre-
sponding vinyl chloride and vinyl bromide, respectively, in
excellent yields (Scheme 5).[17] Subsequently, we also at-
tempted the hydroxylation of Z-2d, affording b-ketoamide 5
in 81% yield.[9c] In addition, the Suzuki coupling of Z-2d
with iodobenzene produced the coupled product in 96%
yield without loss of geometrical purity.[18]
To unveil the mechanism, the reaction of 1n was then
conducted in the presence of iPrOD. It was interesting to
observe that the reaction afforded 96% yield of [D]-2n with
50% deuterium incorporation at the allylic position and
46% at the nitrogen atom; in fact, it was observed that the
reaction of 1t without NH afforded [D]-2t with 84% deute-
rium incorporation at the allylic position (Scheme 6).
Scheme 3. Borylcupration of 4,4-disubstituted allenamides.
It is generally believed that phosphine copper(I) boryl
complexes [(PR3)CuACTHNUTRGNEUNG(boryl)] are the active species in catalyt-
ic borylcupration reactions.[6] The active species can be
easily generated from the phosphine ligand coordination
plus a transmetalation reaction between CuCl and B2ACHTUNGTRENNUNG(pin)2.
According to the experimentally observed regioselectivity,
the boryl moiety installs exclusively on the central allene
carbon. Therefore, the possibilities of two alternative path-
ways, related to this b-borylation regioselectivity, were in-
vestigated by DFT calculations[19] based on the substrate
model N-benzylbuta-2,3-dienamide 1 and the model phos-
phine copper(I) boryl complex [(PMe3)Cu(BR)] (R=
-OCH2CH2O-), in which the aryl groups in the phosphine
Figure 1. ORTEP representation of Z-2q.
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X. Zhang, S. Ma et al.
ligand and the methyl groups in
the Bpin were replaced by CH3
and H, respectively. As shown
in Figure 2,[20] coordination of
the active species [(PMe3)-
AHCTUNGTRENNUNG
considered
separately.
The
metal-h2-allene
intermediate
1A was found to be slightly
lower in free energy and elec-
Scheme 5. Versatile transformations of the borylated product.
tronic energy than 1B. From
1A and 1B, the coordinated C=
C bond undergoes an insertion
via transition states TS1A and TS1B to give the b-boryl al-
kenyl complexes 2A and 2B, respectively. Intermediate 2B
was more stable than 2A by 4.5 kcalmolÀ1, probably due to
coordination of the C=O moiety with the copper(I) metal
À
center in 2B (Cu O bond length 2.480 ꢁ). Nevertheless,
transition state TS1B, which leads to the formation of the
more stable intermediate 2B, was calculated to hold a
higher barrier for insertion than TS1A. In TS1A, the C=O
moiety coordinates with the copper(I) metal center with a
À
Cu O bond length of 2.697 ꢁ, resulting in a lower barrier of
TS1A than that of TS1B by 4.6 kcalmolÀ1 (8.2 vs. 12.8 kcal
molÀ1). The kinetically favorable intermediate 2A quickly
isomerizes to the more stable intermediate 2B, with a very
small barrier of 1.9 kcalmolÀ1, through metal migration
from the a-position to the g-position. Finally, g-protonolysis
Scheme 6. Control experiments in the presence of iPrOH or iPrOD.
À
of the allylic C Cu bond in 2B or 2A by MeOH produces
Figure 2. Energy profiles calculated for possible pathways of the borylation of allenamide 1 catalyzed by [(PMe3)Cu
and electronic energies (in parentheses) are given in kcalmolÀ1
ACHTUNGTRNE(NUNG Bpin)]. The relative free energies
.
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Borylcupration of Allenes
FULL PAPER
the major product 3 or its re-
gioisomer 4, and generates
copper-alkoxide, which is then
followed by a metathesis step
with B2ACHTUNGTRENNUNG(pin)2 to regenerate the
active species [(PMe3)Cu(BR)]
and complete the catalytic
cycle. Thus, it is the stability of
2B over 2A that controls the
regioselectivity of this borylcup-
ration reaction. It is clear that
the reaction predominantly
takes place with the amide-sub-
stituted C=C bond and the
rate-limiting step is insertion of
the coordinated allenamide into
À
the Cu B bond (Figure 2).
The stereoselectivity of the
reaction was further rational-
ized by DFT calculations on the
model substrate N-benzylpenta-
2,3-dienamide (1m). Only the
two competing transition states
of the rate-limiting insertion
step were further considered,
which are denoted as TS1A_Z
Figure 3. The calculated transition states with selected structural parameters (distances in ꢁ) for the insertion
À
of the model allenamide 1m into the Cu B bond. The relative free energies and electronic energies (in paren-
theses) are given in kcalmolÀ1
.
and TS1A_E (Figure 3), respectively.[21] As shown in
Figure 3, TS1A_Z, which leads to the formation of the Z
isomer, was found to be more stable in free energy than
TS1A_E by 3.8 kcalmolÀ1, thus, accounting for the observed
overwhelming formation of Z products. In TS1A_E, the
boryl group suffers a severe steric interaction with the g-sub-
stituent of the allenamide (H···H distance of only 2.705 ꢁ).
The angle a must open up to reduce the steric interaction,
resulting in reduced stability of TS1A_E. Therefore, boryl
addition always occurs on the opposite side of the g-sub-
stituent to produce the more stable Z isomer.
Based on these observations and on the results of the
DFT study, a catalytic cycle is proposed as shown in
Scheme 7. Firstly, the copper-boryl complex PCu-BACTHUNTGRNEUNG(pin)
adds to the C=C double bond next to the amide group, with
boron always connected to the middle carbon atom. Subse-
quently, Cu migrates from the a-position to the g-position in
the allylic unit, forming the more stable six-membered cyclic
intermediate with chelation between Cu and C=O. Finally,
Scheme 7. Summary of the catalytic cycle for the borylation of allen-
AHCTUNGTRENGNaUN mide.
À
g-protonolysis of the allylic C Cu bond with iPrOH produ-
enoamides with exclusive Z C=C bond geometry. The excel-
lent regio- and stereoselectivity has been validated by DFT
studies, which may be used as the principle for tuning the se-
lectivities in such borylcuprations of other functionalized al-
lenes. These otherwise difficult to prepare borylated prod-
ucts are highly functionalized and thus, are very useful inter-
ces the final product Z-2 due to the severe steric interaction
between the boryl group and the larger g-substituent of the
allenamide.
À
Conclusion
mediates for subsequent elaboration of the C B, C=C, and
amide functionalities for the synthesis of complex structures.
Further studies examining the synthetic application of this
method and the mechanism are underway in this laboratory.
We have developed an efficient copper-catalyzed borylcup-
ration of 2,3-allenamides by using a catalytic amount of
CuCl, P(p-MeOC6H4)3, and K2CO3 as well as iPrOH as the
proton source to produce the b-borylated b,g-unsaturated
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X. Zhang, S. Ma et al.
1.00 mmol), and Et2O (2 mL) afforded Z-2d (174.1 mg, 87%) after puri-
fication (petroleum ether/ethyl acetate=10:1) as
Experimental Section
a
liquid. 1H NMR
(300 MHz, CDCl3): d=7.35–7.18 (m, 5H; Ar-H), 6.85 (brs, 1H; NH),
6.30 (d, J=9.6 Hz, 1H; CH=C), 4.48–4.33 (m, 2H; CH2Ph), 3.42 (dd, J1 =
10.2 Hz, J2 =6.0 Hz, 1H; COCH), 2.94–2.76 (m, 1H; CH), 2.02–1.88 (m,
1H; CHH), 1.83–1.67 (m, 1H; CHH), 1.39–1.06 (m, 16H; 2ꢂCH2 and B-
General methods: All reactions were carried out in oven-dried Schlenk
tubes under an argon atmosphere. Et2O and THF were distilled over
sodium wire using benzophenone as the indicator under argon atmos-
phere. iPrOH was distilled using magnesium turnings as drying agent
under argon.
AHCTUNGTREN(GNUN pin)), 0.98 (d, J=6.6 Hz, 3H; CH3), 0.97 (d, J=6.3 Hz, 3H; CH3),
0.87 ppm (t, J=7.1 Hz, 3H; CH3); 13C NMR (75.4 MHz, CDCl3): d=
174.6, 157.2, 138.7, 128.4, 127.6, 127.1, 83.5, 48.3, 43.4, 31.2, 30.0, 27.6,
24.7, 24.1, 22.50, 22.47, 22.3, 13.9 ppm; IR (neat): n˜ =3374, 2960, 2869,
1657, 1539, 1466, 1371, 1348, 1303, 1271, 1230, 1142 cmÀ1; MS (70 eV, EI):
m/z (%): 399 (8.52) [M]+, 91 (100); HRMS: m/z calcd for C24H38BNO3:
399.2945 [M]+; found: 399.2942.
Typical reaction procedure for the copper-catalyzed borylcupration of
2,3-allenamides—Preparation of N-benzyl-2-butyl-3-(4,4,5,5-tetramethyl-
1,3,2-dioxaborolan-2-yl)pent-3-(Z)-enamide (Z-2a): To an oven-dried
Schlenk tube equipped with a magnetic stirring bar were added sequen-
tially bis(pinacolato)diboron (153.0 mg, 0.60 mmol), P(p-MeOC6H4)3
(10.6 mg, 0.03 mmol), CuCl (2.5 mg, 0.025 mmol), K2CO3 (13.9 mg,
Preparation of (Z)-N-benzyl-2-butyl-5-methyl-3-(4,4,5,5-tetramethyl-1,3,2-
dioxaborolan-2-yl)hex-3-(Z)-enamide (Z-2d) on a one gram scale: The
reaction of bis(pinacolato)diboron (1.1201 g, 4.42 mmol), P(p-MeOC6H4)3
(77.6 mg, 0.22 mmol), CuCl (17.9 mg, 0.18 mmol), K2CO3 (101.7 mg,
0.10 mmol), 1a (123.0 mg, 0.50 mmol), iPrOH (78 mL, d=0.784 gmLÀ1
,
60.1 mg, 1.00 mmol), and Et2O (2 mL) under argon. The mixture was stir-
red at RT for 2 h and monitored by TLC. Upon completion, the resulting
mixture was filtered through a short column of silica gel eluted with
Et2O and concentrated. The residue was purified by chromatography on
silica gel (petroleum ether/ethyl acetate=10:1) to afford Z-2a (176.6 mg,
0.74 mmol), 1d (1.0060 g, 3.68 mmol), iPrOH (574 mL, d=0.784 gmLÀ1
,
442.3 mg, 7.36 mmol), and Et2O (10 mL) afforded Z-2d (1.2731 g, 86%)
after purification (petroleum ether/ethyl acetate=10:1) as a liquid.
1
94%) as a liquid. H NMR (300 MHz, CDCl3): d=7.35–7.19 (m, 5H; Ar-
Preparation of (Z)-N-benzyl-2-butyl-6-methyl-3-(4,4,5,5-tetramethyl-1,3,2-
dioxaborolan-2-yl)hept-3-(Z)-enamide (Z-2e): The reaction of bis(pinaco-
H), 6.77 (brs, 1H; NH), 6.62 (q, J=6.8 Hz, 1H; CH=C), 4.47–4.33 (m,
2H; CH2Ph), 3.44 (dd, J1 =9.8 Hz, J2 =5.9 Hz, 1H; COCH), 2.05–1.90
(m, 1H; CHH), 1.86–1.68 (m, 4H; =CH3 and CHH), 1.38–1.08 (m, 16H;
lato)diboron
0.03 mmol), CuCl (2.4 mg, 0.025 mmol), K2CO3 (13.9 mg, 0.10 mmol), 1e
(142.1 mg, 0.50 mmol), iPrOH (78 mL, d=0.784 gmLÀ1
60.1 mg,
1.00 mmol), and Et2O (2 mL) afforded Z-2e (176.2 mg, 86%) after purifi-
cation (petroleum ether/ethyl acetate=15:1) as
liquid. 1H NMR
(152.0 mg,
0.60 mmol),
P(p-MeOC6H4)3
(10.7 mg,
2ꢂCH2 and
BACHTUNGTRENNUNG
(pin)), 0.87 ppm (t, J=7.1 Hz, 3H; CH3); 13C NMR
,
(75.4 MHz, CDCl3): d=174.4, 144.8, 138.7, 128.4, 127.7, 127.1, 83.5, 47.7,
43.5, 31.1, 29.9, 24.8, 24.1, 22.5, 14.7, 13.9 ppm; IR (neat): n˜ =3369, 2977,
2929, 1656, 1535, 1455, 1409, 1384, 1344, 1305, 1215, 1139 cmÀ1; MS
(70 eV, EI): m/z (%): 371 (14.63) [M]+, 91 (100); HRMS: m/z calcd for
C22H34BNO3: 371.2632 [M]+; found: 371.2631.
a
(300 MHz, CDCl3): d=7.35–7.18 (m, 5H; Ar-H), 6.84 (brs, 1H; NH),
6.51 (t, J=7.2 Hz, 1H; CH=C), 4.46–4.31 (m, 2H; CH2Ph), 3.52–3.38 (m,
1H; COCH), 2.20–2.08 (m, 2H; CH2), 2.05–1.88 (m, 1H; CHH), 1.83–
Preparation of (Z)-N-benzyl-2-butyl-3-(4,4,5,5-tetramethyl-1,3,2-dioxabor-
olan-2-yl)hex-3-(Z)-enamide (Z-2b): The reaction of bis(pinacolato)di-
boron (152.0 mg, 0.60 mmol), P(p-MeOC6H4)3 (10.4 mg, 0.03 mmol),
CuCl (2.4 mg, 0.025 mmol), K2CO3 (13.9 mg, 0.10 mmol), 1b (128.8 mg,
0.50 mmol), iPrOH (78 mL, d=0.784 gmLÀ1, 60.1 mg, 1.00 mmol), and
Et2O (2 mL) afforded Z-2b (177.4 mg, 92%) after purification (petrole-
um ether/ethyl acetate=10:1) as a liquid. 1H NMR (300 MHz, CDCl3):
d=7.35–7.20 (m, 5H; Ar-H), 6.81 (brs, 1H; NH), 6.50 (t, J=7.1 Hz, 1H;
CH=C), 4.40 (d, J=5.4 Hz, 2H; CH2Ph), 3.41 (dd, J1 =9.9 Hz, J2 =5.7 Hz,
1H; COCH), 2.34–2.18 (m, 2H; CH2), 2.04–1.85 (m, 1H; CHH), 1.83–
1.63 (m, 2H; CHH and CH), 1.40–1.02 (m, 16H; 2ꢂCH2 and BACHTUNGTRENNUNG(pin)),
0.98–0.78 ppm (m, 9H; 3ꢂCH3); 13C NMR (75.4 MHz, CDCl3): d=174.4,
149.6, 138.6, 128.3, 127.6, 127.0, 83.4, 48.2, 43.4, 37.8, 31.2, 30.0, 28.3, 24.7,
24.0, 22.50, 22.48, 22.42, 13.9 ppm; IR (neat): n˜ =3372, 2956, 2871, 1662,
1533, 1466, 1406, 1372, 1351, 1304, 1215, 1141, 1028 cmÀ1; MS (70 eV, EI):
m/z (%): 413 (25.42) [M]+, 91 (100); HRMS: m/z calcd for C25H40BNO3:
413.3101 [M]+; found: 413.3102.
Preparation of (Z)-N-benzyl-2-butyl-4-cyclohexanyl-3-(4,4,5,5-tetramethyl-
1,3,2-dioxaborolan-2-yl)butyl-3-(Z)-enamide (Z-2 f): The reaction of bis-
1.66 (m, 1H; CHH), 1.38–1.07 (m, 16H; 2ꢂCH2 and B
G
ACHTUNGTRENNUNG
7.5 Hz, 3H; CH3), 0.87 ppm (t, J=7.2 Hz, 3H; CH3); 13C NMR
(75.4 MHz, CDCl3): d=174.6, 152.1, 138.7, 128.4, 127.7, 127.1, 83.5, 48.1,
43.5, 31.1, 30.0, 24.8, 24.1, 22.5, 22.1, 13.9, 13.5 ppm; IR (neat): n˜ =3370,
2961, 2930, 2872, 1656, 1536, 1456, 1405, 1372, 1348, 1303, 1216, 1140,
1028 cmÀ1; MS (70 eV, EI): m/z (%): 385 (4.97) [M]+, 91 (100); HRMS:
m/z calcd for C23H36BNO3: 385.2788 [M]+; found: 385.2790.
,
a
(300 MHz, CDCl3): d=7.34–7.18 (m, 5H; Ar-H), 6.85 (t, J=5.0 Hz, 1H;
NH), 6.30 (d, J=9.3 Hz, 1H; CH=C), 4.40 (d, J=5.4 Hz, 2H; CH2Ph),
3.42 (dd, J1 =10.1 Hz, J2 =5.9 Hz, 1H; COCH), 2.58–2.43 (m, 1H; CH),
2.02–1.88 (m, 1H; CHH), 1.82–1.53 (m, 6H; 3ꢂCH2), 1.41–1.02 (m, 21H;
Preparation of (Z)-N-benzyl-2-butyl-3-(4,4,5,5-tetramethyl-1,3,2-dioxabor-
olan-2-yl)hept-3-(Z)-enamide (Z-2c): The reaction of bis(pinacolato)di-
boron (152.4 mg, 0.60 mmol), P(p-MeOC6H4)3 (10.6 mg, 0.03 mmol),
CuCl (2.5 mg, 0.025 mmol), K2CO3 (13.8 mg, 0.10 mmol), 1c (136.0 mg,
0.50 mmol), iPrOH (78 mL, d=0.784 gmLÀ1, 60.1 mg, 1.00 mmol), and
Et2O (2 mL) afforded Z-2c (180.1 mg, 90%) after purification (petrole-
um ether/ethyl acetate=10:1) as a liquid. 1H NMR (300 MHz, CDCl3):
d=7.35–7.19 (m, 5H; Ar-H), 6.81 (brs, 1H; NH), 6.50 (t, J=7.2 Hz, 1H;
CH=C), 4.39 (d, J=5.7 Hz, 2H; CH2Ph), 3.42 (dd, J1 =9.8 Hz, J2 =5.9 Hz,
1H; COCH), 2.28–2.16 (m, 2H; CH2), 2.03–1.87 (m, 1H; CHH), 1.83–
4ꢂCH2 and CH and
BACTHNGUTRENU(NG pin)), 0.87 ppm (t, J=7.1 Hz, 3H; CH3);
13C NMR (75.4 MHz, CDCl3): d=174.7, 155.8, 138.7, 128.3, 127.6, 127.0,
83.4, 48.3, 43.4, 37.4, 32.4, 32.3, 31.2, 30.0, 25.8, 25.52, 25.49, 24.7, 24.0,
22.5, 13.9 ppm; IR (neat): n˜ =3370, 2924, 2852, 1655, 1536, 1452, 1404,
1372, 1344, 1304, 1271, 1228, 1141 cmÀ1; MS (70 eV, EI): m/z (%): 439
(13.88) [M]+, 91 (100); HRMS: m/z calcd for C27H42BNO3: 439.3258
[M]+; found: 439.3260.
Preparation of (Z)-N-benzyl-2-octanyl-3-(4,4,5,5-tetramethyl-1,3,2-dioxa-
borolan-2-yl)non-3-(Z)-enamide (Z-2g): The reaction of bis(pinacolato)-
diboron (153.0 mg, 0.60 mmol), P(p-MeOC6H4)3 (10.7 mg, 0.03 mmol),
CuCl (2.4 mg, 0.025 mmol), K2CO3 (13.9 mg, 0.10 mmol), 1g (177.5 mg,
0.50 mmol), iPrOH (78 mL, d=0.784 gmLÀ1, 60.1 mg, 1.00 mmol), and
Et2O (2 mL) afforded Z-2g (207.6 mg, 86%) after purification (petrole-
um ether/ethyl acetate=10:1) as a liquid. 1H NMR (300 MHz, CDCl3):
d=7.34–7.18 (m, 5H; Ar-H), 6.81 (t, J=5.3 Hz, 1H; NH), 6.51 (t, J=
7.2 Hz, 1H; CH=C), 4.39 (d, J=5.1 Hz, 2H; CH2Ph), 3.42 (dd, J1 =
9.9 Hz, J2 =6.0 Hz, 1H; COCH), 2.38–2.13 (m, 2H; CH2), 2.05–1.85 (m,
1H; CHH), 1.83–1.65 (m, 1H; CHH), 1.48–1.18 (m, 18H; 9ꢂCH2), 1.16
1.68 (m, 1H; CHH), 1.52–1.06 (m, 18H; 3ꢂCH2 and BACTHNUTRGENU(GN pin)), 0.96–
0.82 ppm (m, 6H; 2ꢂCH3); 13C NMR (75.4 MHz, CDCl3): d=174.5,
150.4, 138.7, 128.4, 127.6, 127.1, 83.5, 48.2, 43.4, 31.2, 30.9, 30.0, 24.7, 24.0,
22.5, 22.1, 13.91, 13.88 ppm; IR (neat): n˜ =3370, 2958, 2929, 2871, 1656,
1535, 1455, 1405, 1373, 1349, 1304, 1216, 1140 cmÀ1; MS (70 eV, EI): m/z
(%): 399 (13.40) [M]+, 91 (100); HRMS: m/z calcd for C24H38BNO3:
399.2945 [M]+; found: 399.2946.
Preparation of (Z)-N-benzyl-2-butyl-5-methyl-3-(4,4,5,5-tetramethyl-1,3,2-
dioxaborolan-2-yl)hex-3-(Z)-enamide (Z-2d): The reaction of bis(pinaco-
lato)diboron
0.03 mmol), CuCl (2.5 mg, 0.025 mmol), K2CO3 (13.9 mg, 0.10 mmol), 1d
(135.7 mg, 0.50 mmol), iPrOH (78 mL, d=0.784 gmLÀ1
60.1 mg,
(153.0 mg,
0.60 mmol),
P(p-MeOC6H4)3
(10.6 mg,
(s, 6H; B
ACHUTGTNRNEUG(N pin)), 1.11 (s, 6H; BACHTUTGNREN(NUNG pin)), 0.87 ppm (t, J=6.8 Hz, 6H; 2ꢂ
,
CH3); 13C NMR (75.4 MHz, CDCl3): d=174.4, 150.6, 138.6, 128.3, 127.6,
7198
www.chemeurj.org
ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2013, 19, 7193 – 7202

Borylcupration of Allenes
FULL PAPER
127.0, 83.4, 48.0, 43.4, 31.7, 31.5, 31.4, 29.34, 29.32, 29.1, 28.8, 28.6, 27.7,
24.6, 24.0, 22.5, 22.4, 14.0, 13.8 ppm; IR (neat): n˜ =3371, 2956, 2925, 2856,
1658, 1529, 1456, 1405, 1374, 1349, 1305, 1215, 1140, 1109, 1030 cmÀ1; MS
(70 eV, EI): m/z (%): 483 (17.45) [M]+, 91 (100); HRMS: m/z calcd for
C30H50BNO3: 483.3884 [M]+; found: 483.3885.
COCH), 2.12–1.97 (m, 1H; CHH), 1.96–1.80 (m, 1H; CHH), 1.37–1.08
(m, 16H; 2ꢂCH2 and
BACTHNGUTRENU(NG pin)), 0.84 ppm (t, J=6.8 Hz, 3H; CH3);
13C NMR (75.4 MHz, CDCl3): d=173.6, 139.2, 138.4, 137.5, 130.7, 128.3,
127.6, 127.29, 127.26, 127.0, 83.8, 49.1, 43.5, 31.7, 29.9, 24.7, 24.0, 22.4,
13.8 ppm; IR (neat): n˜ =3374, 2930, 2860, 1666, 1588, 1508, 1369, 1341,
1312, 1216, 1141 cmÀ1; MS (70 eV, EI): m/z (%): 439 (17.52) [M]+, 91
(100); HRMS: m/z calcd for C25H34BNO3S: 439.2352 [M]+; found:
439.2354.
Preparation of (Z)-N-benzyl-2-butyl-4-benzyl-3-(4,4,5,5-tetramethyl-1,3,2-
dioxaborolan-2-yl)butyl-3-(Z)-enamide (Z-2h): The reaction of bis(pina-
colato)diboron (151.0 mg, 0.60 mmol), P(p-MeOC6H4)3 (10.5 mg,
0.03 mmol), CuCl (2.4 mg, 0.025 mmol), K2CO3 (13.9 mg, 0.10 mmol), 1h
Preparation of (Z)-N-benzyl-2-tosyl-3-(4,4,5,5-tetramethyl-1,3,2-dioxabor-
olan-2-yl)pent-3-(Z)-enamide (Z-2l): The reaction of bis(pinacolato)di-
boron (152.4 mg, 0.60 mmol), P(p-MeOC6H4)3 (10.6 mg, 0.03 mmol),
CuCl (2.4 mg, 0.025 mmol), K2CO3 (13.9 mg, 0.10 mmol), 1l (138.6 mg,
0.50 mmol), iPrOH (78 mL, d=0.784 gmLÀ1, 60.1 mg, 1.00 mmol), and
Et2O (2 mL) afforded Z-2l (134.7 mg, 67%) after purification (petroleum
ether/ethyl acetate=10:1) as a liquid. 1H NMR (300 MHz, CDCl3): d=
7.33–7.18 (m, 7H; Ar-H), 7.21 (d, J=8.1 Hz, 2H; Ar-H), 6.68–6.58 (m,
2H; CH=C and NH), 4.74 (s, 1H; COCH), 4.55 (dd, J1 =15.2 Hz, J2 =
6.2 Hz, 1H; CHHPh), 4.37 (dd, J1 =14.9 Hz, J2 =5.0 Hz, 1H; CHHPh),
2.29 (s, 3H; PhCH3), 1.80 (d, J=6.6 Hz, 3H; =CCH3), 1.10 ppm (s, 12H;
(158.0 mg, 0.50 mmol), iPrOH (78 mL, d=0.784 gmLÀ1
,
60.1 mg,
1.00 mmol), and Et2O (2 mL) afforded Z-2h (190.3 mg, 87%) after puri-
fication (petroleum ether/ethyl acetate=10:1) as a white solid; m.p. 75–
768C (n-hexane/ethyl ether); 1H NMR (300 MHz, CDCl3): d=7.34–7.13
(m, 10H; Ar-H), 6.80 (t, J=5.0 Hz, 1H; NH), 6.63 (t, J=7.2 Hz, 1H;
CH=C), 4.48–4.34 (m, 2H; CH2Ph), 3.63–3.38 (m, 3H; COCH and =
CCH2), 2.08–1.93 (m, 1H; CHH), 1.88–1.73 (m, 1H; CHH), 1.40–1.22
(m, 4H; 2ꢂCH2), 1.14 (s, 6H; BACTHNUTRGENNU(G pin)), 1.09 (s, 6H; BACHTUNGTNER(NUGN pin)), 0.88 ppm (t,
J=7.1 Hz, 3H; CH3); 13C NMR (75.4 MHz, CDCl3): d=174.2, 148.1,
139.7, 138.6, 128.7, 128.43, 128.42, 127.6, 127.1, 126.0, 83.6, 48.3, 43.5,
35.2, 31.2, 30.0, 24.7, 24.1, 22.5, 13.9 ppm; IR (neat): n˜ =3270, 2974, 2930,
1644, 1559, 1454, 1372, 1299, 1222, 1142, 1028 cmÀ1; MS (70 eV, EI): m/z
(%): 447 (15.39) [M]+, 91 (100); elemental analysis calcd (%) for
C28H38BNO3: C 75.16, H 8.56, N 3.13; found: C 75.29, H 8.31, N 3.01.
BACTHNUTRGNEUNG
(pin)); 13C NMR (75.4 MHz, CDCl3): d=173.1, 143.2, 138.5, 136.8,
136.1, 129.1, 128.3, 128.2, 127.5, 127.0, 83.5, 52.6, 43.6, 24.6, 24.2, 20.9,
14.6 ppm; IR (neat): n˜ =3350, 2977, 1656, 1513, 1381, 1335, 1307, 1146,
1133 cmÀ1; MS (70 eV, EI): m/z (%): 405 (15.41) [M]+, 91 (100); HRMS:
m/z calcd for C25H32BNO3: 405.2475 [M]+; found: 405.2477.
Preparation of (Z)-N-benzyl-2-methyl-4-phenyl-3-(4,4,5,5-tetra-methyl-
1,3,2-dioxaborolan-2-yl)butyl-3-(Z)-enamide (Z-2i): The reaction of bis-
ACHTUNGTRENNUNG
Preparation of (Z)-N-benzyl-3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-
yl)pent-3-(Z)-enamide (Z-2m): The reaction of bis(pinacolato)diboron
(152.6 mg, 0.60 mmol), P(p-MeOC6H4)3 (10.6 mg, 0.03 mmol), CuCl
(2.4 mg, 0.025 mmol), K2CO3 (13.9 mg, 0.10 mmol), 1m (94.0 mg,
0.50 mmol), iPrOH (78 mL, d=0.784 gmLÀ1, 60.1 mg, 1.00 mmol), and
THF (2 mL) afforded Z-2m (142.3 mg, 90%) after purification (petrole-
um ether/ethyl acetate=5:1) as a liquid. 1H NMR (300 MHz, CDCl3):
d=7.35–7.21 (m, 5H; Ar-H), 6.65 (q, J=6.9 Hz, 1H; =CH), 6.37 (brs,
1H; NH), 4.40 (d, J=5.4 Hz, 2H; CH2Ph), 3.16 (s, 2H; COCH2), 1.84 (d,
,
a
(300 MHz, CDCl3): d=7.45–7.21 (m, 11H; Ar-H and CH=C), 6.73 (s,
1H; NH), 4.53–4.35 (m, 2H; CH2Ph), 3.79 (q, J=7.2 Hz, 1H; COCH),
1.40 (d, J=7.2 Hz, 3H; CH3), 1.23 (s, 6H; BCAHTUNGTREN(NUNG pin)), 1.19 ppm (s, 6H;
B
A
J=6.6 Hz, 3H; =CCH3), 1.16 ppm (s, 12H;
BACTHNGUTERNNUG
(pin)); 13C NMR
129.1, 128.4, 128.2, 127.72, 127.69, 127.2, 83.8, 43.6, 42.0, 24.8, 24.2,
17.8 ppm; IR (neat): n˜ =3367, 2977, 2932, 1658, 1495, 1451, 1364, 1313,
1264, 1132 cmÀ1; MS (70 eV, EI): m/z (%): 391 (20.42) [M]+, 91 (100);
HRMS: m/z calcd for C24H30BNO3: 391.2319 [M]+; found: 391.2318.
(75.4 MHz, CDCl3): d=171.2, 145.5, 138.5, 128.5, 127.7, 127.2, 83.7, 43.5,
36.4, 24.6, 14.8 ppm; IR (neat): n˜ =3378, 2978, 1654, 1533, 1386, 1370,
1336, 1306, 1143, 1110, 1030 cmÀ1; MS (70 eV, EI): m/z (%): 315 (20.21)
[M]+, 91 (100); HRMS: m/z calcd for C18H26BNO3: 315.2006 [M]+;
found: 315.2008.
Preparation of (Z)-N-benzyl-2-octanyl-4-p-methoxyphenyl-3-(4,4,5,5-tetra-
methyl-1,3,2-dioxaborolan-2-yl)butyl-3-(Z)-enamide (Z-2j): The reaction
of bis(pinacolato)diboron (153.5 mg, 0.60 mmol), P(p-MeOC6H4)3
(10.4 mg, 0.03 mmol), CuCl (2.5 mg, 0.025 mmol), K2CO3 (13.5 mg,
Preparation of N-benzyl-4-methyl-3-(4,4,5,5-tetramethyl-1,3,2-dioxaboro-
lan-2-yl)pent-3-enamide (2n): The reaction of bis(pinacolato)diboron
(154.0 mg, 0.60 mmol), P(p-MeOC6H4)3 (10.7 mg, 0.03 mmol), CuCl
(2.5 mg, 0.025 mmol), K2CO3 (13.9 mg, 0.10 mmol), 1n (100.7 mg,
0.50 mmol), iPrOH (78 mL, d=0.784 gmLÀ1, 60.1 mg, 1.00 mmol), and
Et2O (2 mL) afforded 2n (159.7 mg, 97%) after purification (petroleum
ether/ethyl acetate=7:1) as a white solid; m.p. 77–788C (petroleum
ether/ethyl ether); 1H NMR (300 MHz, CDCl3): d=7.34–7.20 (m, 5H;
Ar-H), 6.44 (brs, 1H; NH), 4.40 (d, J=5.7 Hz, 2H; CH2Ph), 3.13 (s, 2H;
COCH2), 2.05 (s, 3H; =CCH3), 1.86 (s, 3H; =CCH3), 1.18 ppm (s, 12H;
0.10 mmol), 1j (198.1 mg, 0.50 mmol), iPrOH (78 mL, d=0.784 gmLÀ1
,
60.1 mg, 1.00 mmol), and Et2O (2 mL) afforded Z-2j (215.2 mg, 82%)
after purification (petroleum ether/ethyl acetate=10:1) as a white solid;
m.p. 81–828C (n-hexane/ethyl ether); 1H NMR (300 MHz, CDCl3): d=
7.50 (d, J=8.7 Hz, 2H; Ar-H), 7.40 (s, 1H; Ar-H), 7.35–7.21 (m, 6H; Ar-
H), 6.94–6.88 (m, 2H; CH=C and NH), 4.54–4.39 (m, 2H; CH2Ph), 3.81
(s, 3H; OMe), 3.66 (dd, J1 =9.3 Hz, J2 =6.6 Hz, 1H; COCH), 1.98–1.68
(m, 2H; CH2), 1.32–1.00 (m, 24H; 6ꢂCH2 and B
N
BACTHNGUTERNNUG
(pin)); 13C NMR (75.4 MHz, CDCl3): d=172.1, 154.6, 138.6, 128.4,
6.8 Hz, 3H; CH3); 13C NMR (75.4 MHz, CDCl3): d=174.9, 159.2, 146.3,
138.6, 131.1, 129.1, 128.5, 127.8, 127.2, 113.6, 83.8, 55.1, 48.8, 43.6, 32.6,
31.7, 29.3, 29.1, 27.7, 24.8, 24.1, 22.6, 14.0 ppm; IR (neat): n˜ =3335, 2924,
2851, 1639, 1604, 1509, 1455, 1379, 1344, 1312, 1285, 1250, 1209, 1175,
1133, 1037 cmÀ1; MS (70 eV, EI): m/z (%): 519 (3.34) [M]+, 91 (100); ele-
mental analysis calcd (%) for C32H46BNO4: C 73.98, H 8.92, N 2.70;
found: C 73.96, H 9.05, N 2.75.
127.5, 127.1, 83.2, 43.3, 38.9, 24.62, 24.59, 22.0 ppm; IR (neat): n˜ =3232,
2978, 2929, 2858, 1640, 1522, 1371, 1351, 1143, 1070 cmÀ1; MS (70 eV, EI):
m/z (%): 329 (19.62) [M]+, 91 (100); elemental analysis calcd (%) for
C19H28BNO3: C 69.31, H 8.57, N 4.25; found: C 69.44, H 8.45, N 4.17.
Preparation of N-phenyl-4-methyl-3-(4,4,5,5-tetramethyl-1,3,2-dioxaboro-
lan-2-yl)pent-3-enamide (2o): The reaction of bis(pinacolato)diboron
(153.0 mg, 0.60 mmol), P(p-MeOC6H4)3 (10.8 mg, 0.03 mmol), CuCl
(2.4 mg, 0.025 mmol), K2CO3 (13.8 mg, 0.10 mmol), 1o (94.0 mg,
0.50 mmol), iPrOH (78 mL, d=0.784 gmLÀ1, 60.1 mg, 1.00 mmol), and
Et2O (2 mL) afforded 2o (157.7 mg, 100%) after purification (petroleum
ether/ethyl acetate=7:1) as a white solid; m.p. 99–1008C (n-hexane/ethyl
ether); 1H NMR (300 MHz, CDCl3): d=8.25 (brs, 1H; NH), 7.50 (d, J=
7.8 Hz, 2H; Ar-H), 7.33–7.24 (m, 2H; Ar-H), 7.08–7.01 (m, 1H; Ar-H),
3.20 (s, 2H; COCH2), 2.07 (s, 3H; =CCH3), 1.93 (s, 3H; =CCH3),
Preparation of (Z)-N-benzyl-2-butyl-4-thenyl-3-(4,4,5,5-tetramethyl-1,3,2-
dioxaborolan-2-yl)butyl-3-(Z)-enamide (Z-2k): The reaction of bis(pina-
colato)diboron (153.0 mg, 0.60 mmol), P(p-MeOC6H4)3 (10.8 mg,
0.03 mmol), CuCl (2.6 mg, 0.025 mmol), K2CO3 (13.7 mg, 0.10 mmol), 1k
(154.6 mg, 0.50 mmol), iPrOH (78 mL, d=0.784 gmLÀ1
,
60.1 mg,
1.00 mmol), and Et2O (2 mL) afforded Z-2k (140.5 mg, 64%) after puri-
fication (petroleum ether/ethyl acetate=15:1) as
liquid. 1H NMR
a
(300 MHz, CDCl3): d=7.48–7.43 (m, 2H; Ar-H), 7.36–7.18 (m, 6H; Ar-
H), 7.04 (dd, J1 =5.0 Hz, J2 =3.8 Hz, 1H; CH=C), 6.92 (t, J=5.3 Hz, 1H;
NH), 4.48 (dd, J1 =14.7 Hz, J2 =5.4 Hz, 1H; CHHPh), 4.37 (dd, J1 =
14.7 Hz, J2 =5.1 Hz, 1H; CHHPh), 3.92 (dd, J1 =9.5 Hz, J2 =5.9 Hz, 1H;
(pin)); 13C NMR (75.4 MHz, CDCl3): d=170.5,
1.32 ppm (s, 12H; BACHTUNTGNRUEGN
155.6, 138.7, 128.8, 123.4, 119.1, 83.5, 40.3, 24.8, 24.6, 22.1 ppm; IR (neat):
n˜ =3293, 2930, 2856, 1734, 1661, 1638, 1599, 1532, 1441, 1370, 1296, 1252,
1145, 1031, 1004 cmÀ1; MS (70 eV, EI): m/z (%): 315 (85.49) [M]+, 77
Chem. Eur. J. 2013, 19, 7193 – 7202
ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
7199

X. Zhang, S. Ma et al.
(100); elemental analysis calcd (%) for C18H26BNO3: C 68.59, H 8.31, N
4.44; found: C 68.74, H 8.25, N 4.33.
bar were added sequentially CuCl2 (81.0 mg, 0.60 mmol), Z-2d (80.4 mg,
0.20 mmol), MeOH (1 mL), and H2O (1 mL). The mixture was stirred at
808C for 2.5 h and monitored by TLC. Upon completion, Et2O (5 mL)
was added to the resulting mixture, then the aqueous phase was extracted
with Et2O (3ꢂ5 mL). The combined organic layer was dried over anhy-
drous Na2SO4. Filtration, evaporation, and chromatography on silica gel
(petroleum ether/ethyl acetate=7:1) afforded 3 (55.6 mg, 90%) as a
liquid. 1H NMR (300 MHz, CDCl3): d=7.37–7.22 (m, 5H; Ar-H), 6.14
(brs, 1H; NH), 5.72 (d, J=10.2 Hz, 1H; CH=C), 4.53–4.39 (m, 2H;
CH2Ph), 3.58 (dd, J1 =10.2 Hz, J2 =4.8 Hz, 1H; COCH), 2.68–2.50 (m,
1H; CH), 2.08–1.93 (m, 1H; CHH), 1.88–1.71 (m, 1H; CHH), 1.43–1.10
(m, 4H; 2ꢂCH2), 1.00 (d, J=6.6 Hz, 3H; CH3), 0.99 (d, J=6.6 Hz, 3H;
CH3), 0.91 ppm (t, J=7.1 Hz, 3H; CH3); 13C NMR (75.4 MHz, CDCl3):
d=170.4, 140.4, 138.1, 129.5, 128.6, 127.4, 127.3, 49.3, 43.6, 29.2, 28.6,
28.5, 22.8, 22.7, 22.4, 13.9 ppm; IR (neat): n˜ =3304, 2959, 2928, 2870,
1651, 1542, 1455, 1362, 1220, 1173, 1029 cmÀ1; MS (70 eV, EI): m/z (%):
Preparation of N-butyl-4-methyl-3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-
2-yl)pent-3-enamide (2p): The reaction of bis(pinacolato)diboron
(152.4 mg, 0.60 mmol), P(p-MeOC6H4)3 (10.6 mg, 0.03 mmol), CuCl
(2.6 mg, 0.025 mmol), K2CO3 (13.9 mg, 0.10 mmol), 1p (83.8 mg,
0.50 mmol), iPrOH (78 mL, d=0.784 gmLÀ1, 60.1 mg, 1.00 mmol), and
Et2O (2 mL) afforded 2p (144.9 mg, 98%) after purification (petroleum
ether/ethyl acetate=7:1) as a liquid. 1H NMR (300 MHz, CDCl3): d=
6.01 (brs, 1H; NH), 3.24–3.15 (m, 2H; CH2), 3.06 (s, 2H; COCH2), 2.05
(s, 3H; =CCH3), 1.83 (s, 3H; =CCH3), 1.50–1.23 (m, 16H; 2ꢂCH2 and B-
ACHTUNGTRENNUNG
(pin)), 0.91 ppm (t, J=7.2 Hz, 3H; CH3); 13C NMR (75.4 MHz, CDCl3):
d=172.0, 153.9, 83.1, 38.8, 31.5, 24.6, 24.5, 21.7, 19.8, 13.6 ppm; IR (neat):
n˜ =3307, 2976, 2930, 2873, 1647, 1541, 1372, 1354, 1294, 1221, 1145,
1063 cmÀ1 MS (70 eV, EI): m/z (%): 295 (35.12) [M]+, 139 (100);
;
HRMS: m/z calcd for C16H30BNO3: 295.2319 [M]+; found: 295.2320.
309 (0.87) [MACTHNUTRGENNUG ACHTUGNTRENNUGN
(37Cl)]+, 307 (2.73) [M(35Cl)]+, 91 (100); HRMS: m/z calcd
Preparation of (Z)-N-benzyl-4-methyl-5,5-dimethyl-3-(4,4,5,5-tetramethyl-
1,3,2-dioxaborolan-2-yl)hex-3-(Z)-enamide (Z-2q): The reaction of bis-
for C18H2635ClNO: 307.1703 [M]+; found: 307.1701.
Preparation of (E)-N-benzyl-2-butyl-3-boromide-5-methyl-hex-3-(E)-en-
amide (4): The reaction of CuBr2 (135.0 mg, 0.60 mmol), Z-2d (79.0 mg,
0.20 mmol), MeOH (1 mL), and H2O (1 mL) afforded 4 (56.3 mg, 81%)
ACHTUNGTRENNUNG
,
after purification (petroleum ether/ethyl acetate=7:1) as
a liquid.
1.00 mmol), and Et2O (2 mL) afforded Z-2q (130.2 mg, 70%) after puri-
fication (petroleum ether/ethyl acetate=7:1) as a pale-yellow solid; m.p.
108–1098C (n-hexane/ethyl ether); H NMR (300 MHz, CDCl3): d=7.34–
1H NMR (300 MHz, CDCl3): d=7.37–7.23 (m, 5H; Ar-H), 6.11 (brs, 1H;
NH), 6.00 (d, J=9.9 Hz, 1H; CH=C), 4.53–4.39 (m, 2H; CH2Ph), 3.52
(dd, J1 =10.2 Hz, J2 =4.5 Hz, 1H; COCH), 2.72–2.53 (m, 1H; CH), 2.09–
1.93 (m, 1H; CHH), 1.82–1.68 (m, 1H; CHH), 1.43–1.09 (m, 4H; 2ꢂ
CH2), 1.00 (d, J=6.6 Hz, 3H; CH3), 0.98 (d, J=6.9 Hz, 3H; CH3),
0.91 ppm (t, J=7.2 Hz, 3H; CH3); 13C NMR (75.4 MHz, CDCl3): d=
170.4, 144.8, 138.1, 128.6, 127.45, 127.36, 122.0, 50.0, 43.7, 29.8, 29.5, 29.2,
22.6, 22.5, 22.4, 13.9 ppm; IR (neat): n˜ =3306, 2958, 2928, 2869, 1651,
1538, 1455, 1362, 1218, 1168, 1153, 1029 cmÀ1; MS (70 eV, EI): m/z (%):
1
7.21 (m, 5H; Ar-H), 6.35 (brs, 1H; NH), 4.44 (d, J=5.4 Hz, 2H;
CH2Ph), 3.36 (s, 2H; COCH2), 1.93 (s, 3H; =CCH3), 1.21 (s, 12H;
BACHTUNGTRENNUNG
(pin)), 1.15 ppm (s, 9H;=(CH3)3); 13C NMR (75.4 MHz, CDCl3): d=
172.0, 158.9, 138.3, 128.3, 127.6, 127.0, 83.2, 43.3, 39.4, 37.4, 30.2, 24.5,
22.4 ppm; IR (neat): n˜ =3264, 2974, 2906, 1648, 1546, 1475, 1455, 1366,
1348, 1288, 1231, 1142, 1063, 1040, 1008 cmÀ1; MS (70 eV, EI): m/z (%):
371 (11.26) [M]+, 91 (100); elemental analysis calcd (%) for
C22H34BNO3: C 71.16, H 9.23, N 3.77; found: C 71.13, H 9.28, N 3.78.
353 (1.24) [MACTHNUTRGENNUG ACHTUGNTRENNUGN
(81Br)]+, 351 (1.12) [M(79Br)]+, 91 (100); HRMS: m/z calcd
for C18H2679BrNO: 351.1198 [M]+; found: 351.1196.
Preparation of (Z)-N-benzyl-4-phenyl-3-(4,4,5,5-tetramethyl-1,3,2-dioxa-
borolan-2-yl)pent-3-(Z)-enamide (Z-2r): The reaction of bis(pinacolato)-
diboron (153.0 mg, 0.60 mmol), P(p-MeOC6H4)3 (10.5 mg, 0.03 mmol),
CuCl (2.6 mg, 0.025 mmol), K2CO3 (13.9 mg, 0.10 mmol), 1r (132.0 mg,
0.50 mmol), iPrOH (78 mL, d=0.784 gmLÀ1, 60.1 mg, 1.00 mmol), and
Et2O (2 mL) afforded Z-2r (148.6 mg, 76%) after purification (petrole-
um ether/ethyl acetate=7:1) as a white solid; m.p. 105–1068C (n-hexane/
ethyl ether); 1H NMR (300 MHz, CDCl3): d=7.34–7.18 (m, 8H; Ar-H),
7.10 (d, J=7.5 Hz, 2H; Ar-H), 6.08 (brs, 1H; NH), 4.37 (d, J=6.0 Hz,
2H; CH2), 2.97 (s, 2H; COCH2), 2.29 (s, 3H; =CCH3), 1.25 ppm (s, 12H;
Preparation of N-benzyl-2-butyl-5-methyl-3-oxohexanamide (5): To an
oven-dried Schlenk tube equipped with a magnetic stirring bar were
added Z-2d (79.9 mg, 0.20 mmol) and THF (1 mL), then NaOH (1 mL,
C=3m) and H2O2 (1 mL, 30% aq.) were added dropwise at 08C within
10 and 5 min, respectively, and the resulting mixture was stirred at RT.
Upon completion, the reaction was quenched with saturated Na2S2O3
(1 mL) and NaOH (1 mL, C=1m), extracted with ethyl acetate (3ꢂ
10 mL), washed with brine, and dried over Na2SO4. Filtration, evapora-
tion, and chromatography on silica gel (petroleum ether/ethyl acetate=
7:1) afforded 5 (47.1 mg, 81%) as a white solid; m.p. 96–978C (n-hexane/
ethyl ether); 1H NMR (300 MHz, CDCl3): d=7.36–7.18 (m, 5H; Ar-H),
6.76 (brs, 1H; NH), 4.51–4.33 (m, 2H; CH2Ph), 3.40 (t, J=7.4 Hz, 1H;
COCHCO), 2.51–2.32 (m, 2H; CH2), 2.13 (hept, J=6.6 Hz, 1H; CH),
1.89–1.72 (m, 2H; CH2), 1.40–1.18 (m, 4H; 2ꢂCH2), 0.93–0.82 ppm (m,
9H; 3ꢂCH3); 13C NMR (75.4 MHz, CDCl3): d=209.4, 168.5, 138.0, 128.6,
127.5, 127.4, 61.0, 51.5, 43.5, 30.6, 29.5, 23.8, 22.4, 22.3, 13.7 ppm; IR
(neat): n˜ =3291, 2956, 2928, 2862, 1707, 1667, 1641, 1558, 1523, 1496,
1456, 1405, 1365, 1344, 1293, 1244, 1219, 1145, 1082, 1042, 1030,
1016 cmÀ1; MS (70 eV, EI): m/z (%): 289 (12.87) [M]+, 91 (100); elemen-
tal analysis calcd (%) for C18H27NO2: C 74.70, H 9.40, N 4.84; found: C
74.37, H 9.53, N 4.75.
BACHTUNGTRENNUNG
(pin)); 13C NMR (75.4 MHz, CDCl3): d=171.9, 154.7, 143.5, 138.4,
128.3, 128.1, 127.6, 127.1, 126.9, 126.7, 83.3, 43.3, 39.9, 24.9, 24.6 ppm; IR
(neat): n˜ =3309, 2983, 2932, 1640, 1526, 1445, 1398, 1362, 1340, 1306,
1205, 1145, 1119, 1040 cmÀ1; MS (70 eV, EI): m/z (%): 391 (15.35) [M]+,
91 (100); elemental analysis calcd (%) for C24H30BNO3: C 73.66, H 7.73,
N 3.58; found: C 73.40, H 7.73, N 3.50.
Preparation of N-benzyl-2,4-dimethyl-5,5-dimethyl-3-(4,4,5,5-tetramethyl-
1,3,2-dioxaborolan-2-yl)pent-3-enamide (2s): The reaction of bis(pinaco-
lato)diboron
0.03 mmol), CuCl (2.6 mg, 0.025 mmol), K2CO3 (13.9 mg, 0.10 mmol), 1s
(108.0 mg, 0.50 mmol), iPrOH (78 mL, d=0.784 gmLÀ1
60.1 mg,
(152.4 mg,
0.60 mmol),
P(p-MeOC6H4)3
(10.4 mg,
,
1.00 mmol), and Et2O (2 mL) afforded 2s (150.5 mg, 87%) after purifica-
tion (petroleum ether/ethyl acetate=10:1) as a white solid; m.p. 112–
1138C (n-hexane/ethyl ether); 1H NMR (300 MHz, CDCl3): d=7.38–7.18
(m, 5H; Ar-H), 6.54 (brs, 1H; NH), 4.48 (dd, J1 =14.7 Hz, J2 =5.7 Hz,
1H; CHH), 4.35 (dd, J1 =15.0 Hz, J2 =5.1 Hz, 1H; CHH), 3.44 (q, J=
7.2 Hz, 1H; COCH), 1.93 (s, 3H; =CCH3), 1.76 (s, 3H; =CCH3), 1.46–
Preparation of (Z)-N-benzyl-2-butyl-3-phenyl-5-methyl-hex-3-(Z)-enamide
(6): To an oven-dried Schlenk tube equipped with a magnetic stirring bar
were added sequentially [PdACTHNUTRGEN(UNG PPh3)4] (11.7 mg, 0.01 mmol), K3PO4
(127.4 mg, 0.6 mmol), Z-2d (79.5 mg, 0.20 mmol), toluene (1 mL), and
PhI (81.8 mg, 0.4 mmol) under argon. The resulting mixture was stirred
at 858C for 24 h and monitored by TLC. Upon completion, the resulting
mixture was filtered through a short column of silica gel eluting with
Et2O (3ꢂ20 mL) and concentrated. The residue was purified by chroma-
tography on silica gel (petroleum ether/ethyl acetate=10:1) to afford 6
(67.2 mg, 96%) as a liquid. 1H NMR (300 MHz, CDCl3): d=7.33–7.17
(m, 10H; Ar-H), 6.23 (t, J=5.1 Hz, 1H; NH), 5.69 (d, J=9.9 Hz, 1H; =
CH), 4.51 (dd, J1 =14.6 Hz, J2 =5.9 Hz, 1H; CHHPh), 4.40 (dd, J1 =
14.4 Hz, J2 =5.4 Hz, 1H; CHHPh), 3.61 (dd, J1 =10.1 Hz, J2 =4.7 Hz, 1H;
COCH), 2.81–2.63 (m, 1H; CH), 2.22–2.07 (m, 1H; CHH), 1.56–1.40 (m,
1.10 ppm (m, 15H; CH3 and BACHTNUTGRNEUNG
(pin)); 13C NMR (75.4 MHz, CDCl3): d=
175.3, 147.5, 138.6, 128.2, 127.4, 126.9, 83.3, 43.3, 43.2, 25.0, 24.8, 24.5,
20.8, 17.3 ppm; IR (neat): n˜ =3317, 2976, 2926, 2870, 1655, 1542, 1456,
1388, 1370, 1333, 1268, 1228, 1214, 1142, 1094 cmÀ1; MS (70 eV, EI): m/z
(%): 343 (27.23) [M]+, 91 (100); elemental analysis calcd (%) for
C20H30BNO3: C 69.98, H 8.81, N 4.08; found: C 70.24, H 8.86, N 3.92.
Synthetic applications of borylated product Z-2d
Preparation of (E)-N-benzyl-2-butyl-3-chloride-5-methyl-hex-3-(E)-enam-
ide (3): To an oven-dried Schlenk tube equipped with a magnetic stirring
7200
www.chemeurj.org
ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2013, 19, 7193 – 7202

Borylcupration of Allenes
FULL PAPER
1H; CHH), 1.32–1.07 (m, 4H; 2ꢂCH2), 1.02 (d, J=6.3 Hz, 3H; CH3),
0.99 (d, J=6.6 Hz, 3H; CH3), 0.78 ppm (t, J=6.9 Hz, 3H; CH3);
13C NMR (75.4 MHz, CDCl3): d=172.8, 142.0, 140.8, 138.2, 136.5, 128.6,
128.1, 127.8, 127.4, 127.2, 127.0, 47.2, 43.9, 29.9, 28.2, 27.9, 23.0, 22.9, 22.4,
13.9 cmÀ1; IR (neat): n˜ =3337, 2956, 2927, 2867, 1654, 1508, 1455, 1361,
1252, 1029 cmÀ1; MS (70 eV, EI): m/z (%): 349 (4.84) [M]+, 292 (100);
HRMS: m/z calcd for C24H31NO: 349.2406 [M]+; found: 349.2407.
Rong Zeng in this group for reproducing the results of Table 2 (entries 3
and 13) and Scheme 2 (Z-2r) presented in this study.
[1] For reviews, see: a) J. Tsuji, Palladium Reagents and Catalysts,
Wiley, Chichester, England, 2004, pp. 218–227; b) D. S. Matteson,
Chem. Rev. 1989, 89, 1535; c) D. S. Matteson, Acc. Chem. Res. 1988,
Mechanistic study
Preparation of N-benzyl-2-deutero-4-methyl-3-(4,4,5,5-tetramethyl-1,3,2-di-
oxaborolan-2-yl)pent-3-enamide ([D]-2n): The reaction of bis(pinacola-
to)diboron (152.6 mg, 0.60 mmol), P(p-MeOC6H4)3 (10.7 mg, 0.03 mmol),
CuCl (2.5 mg, 0.025 mmol), K2CO3 (13.8 mg, 0.10 mmol), 1n (100.6 mg,
0.50 mmol), iPrOD (69.0 mg, 1.00 mmol), and Et2O (2 mL) afforded 2n-d
(155.8 mg, 94%, D%=50%) after purification (petroleum ether/ethyl
acetate=7:1) as a white solid; m.p. 78–798C (petroleum ether/ethyl
ether); 1H NMR (300 MHz, CDCl3): d=7.35–7.21 (m, 5H; Ar-H), 6.42
(brs, 1H; NH), 4.41 (d, J=5.7 Hz, 2H; CH2), 3.13 (d, J=5.4 Hz, 1H;
COCHD), 2.05 (s, 3H; =CCH3), 1.86 (s, 3H; =CCH3), 1.18 ppm (s, 12H;
À
21, 294; for applications of vinylboronates in C C bond formation,
see: d) M. Tobisu, N. Chatani, Angew. Chem. 2009, 121, 3617;
Angew. Chem. Int. Ed. 2009, 48, 3565; e) S. Kotha, K. Lahiri, D. Ka-
shinath, Tetrahedron 2002, 58, 9633.
[2] For reviews, see: a) N. Miyaura, A. Suzuki, Chem. Rev. 1995, 95,
2457; b) A. Suzuki, J. Organomet. Chem. 1999, 576, 147.
[3] a) T. Ohishi, M. Nishiura, Z. Hou, Angew. Chem. 2008, 120, 5876;
Angew. Chem. Int. Ed. 2008, 47, 5792; b) R. Shintani, M. Takeda,
Y.-T. Soh, T. Ito, T. Hayashi, Org. Lett. 2011, 13, 2977; c) J. Takaya,
S. Tadami, K. Ukai, N. Iwasawa, Org. Lett. 2008, 10, 2697.
BACHTUNGTRENNUNG
(pin)); 13C NMR (75.4 MHz, CDCl3): d=172.1, 154.65, 138.6, 128.4,
127.5, 127.1, 83.2, 43.3, 38.6 (t, J=20.3 Hz), 24.6, 22.0; peaks at d=154.70
and 38.9 ppm arise from undeuterated product; IR (neat): n˜ =3257, 3085,
2976, 2927, 1637, 1561, 1496, 1454, 1370, 1352, 1333, 1295, 1273, 1220,
1146, 1110, 1070, 1046, 1026 cmÀ1; MS (70 eV, EI): m/z (%): 330 (10.37)
[4] a) M. Sakai, H. Hayashi, N. Miyaura, Organometallics 1997, 16,
4229; b) S. Sakuma, M. Sakai, R. Itooka, N. Miyaura, J. Org. Chem.
2000, 65, 5951.
[5] For hydroboration of alkenes and alkynes with pinacolborane, see:
a) Y. D. Wang, G. Kimball, A. S. Prashad, Y. Wang, Tetrahedron
Lett. 2005, 46, 8777; b) S. Pereira, M. Srebnik, Organometallics 1995,
14, 3127; c) S. Pereira, M. Srebnik, Tetrahedron Lett. 1996, 37, 3283;
for diboration of alkynes or alkenes, see: d) T. Ishiyama, N. Matsu-
da, N. Miyaura, A. Suzuki, J. Am. Chem. Soc. 1993, 115, 11018; e) T.
Ishiyama, M. Yamamoto, N. Miyaura, Chem. Commun. 1997, 689.
ACTHNUTRGNEUNG
[M(2D)]+, 329 (10.28) [M(1 H)]+, 91 (100); elemental analysis calcd (%)
for C19H27DBNO3: C 69.10, H 8.85, N 4.24; found: C 69.32, H 8.61, N
4.17.
Preparation of N-diethyl-4-methyl-3-(4,4,5,5-tetramethyl-1,3,2-dioxaboro-
lan-2-yl)pent-3-enamide (2t): The reaction of bis(pinacolato)diboron
(153.0 mg, 0.60 mmol), P(p-MeOC6H4)3 (10.6 mg, 0.03 mmol), CuCl
(2.5 mg, 0.025 mmol), K2CO3 (13.8 mg, 0.10 mmol), 1t (83.5 mg,
0.50 mmol), iPrOH (78 mL, d=0.784 gmLÀ1, 60.1 mg, 1.00 mmol), and
Et2O (2 mL) afforded 2t (105.5 mg, 72%) after purification (petroleum
ether/ethyl acetate=3:1) as a white solid; m.p. 46–478C (n-hexane/ethyl
ether); 1H NMR (300 MHz, CDCl3): d=3.43–3.28 (m, 4H; 2ꢂCH2), 3.20
(s, 2H; COCH2), 1.98 (s, 3H; =CCH3), 1.70 (s, 3H; =CCH3), 1.27 (s,
[6] For Cu-catalyzed hydroboration of alkynes with B2ACHTNUTRGNE(UNG pin)2, see: a) J.-
E. Lee, J. Kwon, J. Yun, Chem. Commun. 2008, 733; b) H. R. Kim,
Gu. Jung II, K. Yoo, K. Jang, E. S. Lee, J. Yun, S. U. Son, Chem.
Commun. 2010, 46, 758; c) H. R. Kim, J. Yun, Chem. Commun.
2011, 47, 2943; d) H. Jang, A. R. Zhugralin, Y. Lee, A. H. Hoveyda,
J. Am. Chem. Soc. 2011, 133, 7859; e) A. L. Moure, R. G. Arrayꢃs,
D. J. Cꢃrdenas, I. Alonso, J. C. Carretero, J. Am. Chem. Soc. 2012,
134, 7219; for hydroboration of alkynes promoted by stoichiometric
amouts of a Cu complex, see: f) K. Takahashi, T. Ishiyama, N.
Miyaura, Chem. Lett. 2000, 982; g) K. Takahashi, T. Ishiyama, N.
Miyaura, J. Organomet. Chem. 2001, 625, 47.
12H; BACHTUNGTRENNUNG(pin)), 1.19 (t, J=7.1 Hz, 3H; CH3), 1.12 ppm (t, J=7.1 Hz, 3H;
CH3); 13C NMR (75.4 MHz, CDCl3): d=172.9, 143.9, 81.9, 42.1, 40.6,
35.9, 25.3, 23.9, 21.7, 14.0, 13.0; IR (neat): n˜ =2974, 2930, 2873, 1724,
1627, 1460, 1445, 1430, 1372, 1353, 1319, 1286, 1272, 1255, 1220, 1147,
1136, 1066 cmÀ1; MS (70 eV, EI): m/z (%): 295 (41.01) [M]+, 100 (100);
elemental analysis calcd (%) for C16H30BNO3: C 65.09, H 10.24, N 4.74;
found: C 64.93, H 10.34, N 4.68.
[7] For Pd-catalyzed silaboration of allenes, see: a) M. Suginome, Y.
Ohmori, Y. Ito, Synlett 1999, 1567; b) M. Suginome, Y. Ohmori, Y.
Ito, J. Organomet. Chem. 2000, 611, 403; c) S. Onozawa, Y. Hatana-
ka, M. Tanaka, Chem. Commun. 1999, 1863; d) M. Suginome, T.
Ohmura, Y. Miyake, S. Mitani, Y. Ito, M. Murakami, J. Am. Chem.
Soc. 2003, 125, 11174; e) T. Ohmura, H. Taniguchi, M. Suginome, J.
Am. Chem. Soc. 2006, 128, 13682.
Preparation of N-diethyl-2-deuter-4-methyl-3-(4,4,5,5-tetramethyl-1,3,2-di-
oxaborolan-2-yl)pent-3-enamide ([D]-2t): The reaction of bis(pinacola-
to)diboron (150.0 mg, 0.60 mmol), P(p-MeOC6H4)3 (10.5 mg, 0.03 mmol),
CuCl (2.5 mg, 0.025 mmol), K2CO3 (13.7 mg, 0.10 mmol), 1t (81.4 mg,
0.50 mmol), iPrOD (69.0 mg, 1.00 mmol), and Et2O (2 mL) afforded 2t-d
(102.0 mg, 71%, D%=84%) after purification (petroleum ether/ethyl
acetate=3:1) as a white solid; m.p. 47–488C (n-hexane/ethyl ether);
1H NMR (300 MHz, CDCl3): d=3.43–3.28 (m, 4H; 2ꢂCH2), 3.18 (d, J=
5.7 Hz, 1H; COCHD), 1.98 (s, 3H; =CCH3), 1.71 (s, 3H; =CCH3), 1.27
[8] For transition-metal-catalyzed diboration of allenes, see: a) T. Ish-
iyama, T. Kitano, N. Miyaura, Tetrahedron Lett. 1998, 39, 2357;
b) F.-Y. Yang, C.-H. Cheng, J. Am. Chem. Soc. 2001, 123, 761.
[9] For Pd-catalyzed enantioselective diboration of simple allenes occur-
ring at the more substituted C=C bond in allenes, see: a) N. F. Pelz,
A. R. Woodward, H. E. Burks, J. D. Sieber, J. P. Morken, J. Am.
Chem. Soc. 2004, 126, 16328; b) A. R. Woodward, H. E. Burks,
L. M. Chan, J. P. Morken, Org. Lett. 2005, 7, 5505; c) N. F. Pelz, J. P.
Morken, Org. Lett. 2006, 8, 4557; d) H. E. Burks, S. Liu, J. P.
Morken, J. Am. Chem. Soc. 2007, 129, 8766; for theoretical studies
on the reaction mechanism of Pt-catalyzed diboration of allenes,
see: e) M. Wang, L. Cheng, Z. Wu, Organometallics 2008, 27, 6464.
[10] For uncatalyzed hydroboration of allenes, see: a) R. H. Fish, J. Am.
Chem. Soc. 1968, 90, 4435; b) D. S. Sethi, G. C. Joshi, D. Devaprab-
hakara, Can. J. Chem. 1969, 47, 1083; c) H. C. Brown, R. Liotta,
G. W. Kramer, J. Am. Chem. Soc. 1979, 101, 2966; d) J. Kister, A. C.
DeBaillie, R. Lira, W. R. Roush, J. Am. Chem. Soc. 2009, 131,
14174; e) D. H. Ess, J. Kister, M. Chen, W. R. Roush, Org. Lett.
2009, 11, 5538.
(s, 12H; BACHTUNGTRENNUNG(pin)), 1.19 (t, J=7.1 Hz, 3H; CH3), 1.12 ppm (t, J=7.1 Hz,
3H; CH3); 13C NMR (75.4 MHz, CDCl3): d=172.78, 144.08, 81.81, 42.0,
40.5, 35.4 (t, J=19.1 Hz), 25.2, 23.9, 21.6, 13.9, 12.9 ppm; the peaks at d=
172.84, 144.03, 81.77, 35.8 ppm arise from undeuterated product; IR
(neat): n˜ =2976, 2930, 1626, 1477, 1460, 1443, 1429, 1371, 1352, 1286,
1218, 1147, 1072 cmÀ1; MS (70 eV, EI): m/z (%): 296 (53.20) [M(2D)]+,
295 (49.34) [MACHTUNGTRENNUNG
(1 H)]+, 72 (100); elemental analysis calcd (%) for
C16H29DBNO3: C 64.87, H 10.55, N 4.73; found: C 65.10, H 10.39, N 4.67.
Acknowledgements
Financial support from the National Basic Research Program of China
(No. 2011CB808700) and the National Natural Science Foundation of
China (No. 21232006 and 21102164) is greatly appreciated. We thank Mr
[11] For Pt-catalyzed hydroboration of monosubstituted allenes with
B CHTUNGTREN(NNUG pin)2, see: Y. Yamamoto, R. Fujikawa, A. Yamada, N. Miyaura,
2A
Chem. Lett. 1999, 28, 1069.
Chem. Eur. J. 2013, 19, 7193 – 7202
ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
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X. Zhang, S. Ma et al.
[12] For Cu-catalyzed hydroboration of allenoates by a preactivated di-
boron, see: S. B. Thorpe, X. Guo, W. L. Santos, Chem. Commun.
2011, 47, 424.
[21] The other two transition structures associated with TS1B, which are
denoted as TS1B_1 and TS1B_2, are both higher in free energy (and
electronic energy) than TS1A_Z and TS1A_E. The relative free ener-
gies and electronic energies (in parentheses) of the four transition
structures are shown in kcalmolÀ1. For the details see the Supporting
Information.
[13] W. Yuan, S. Ma, Adv. Synth. Catal. 2012, 354, 1867.
[14] B. Jung, A. H. Hoveyda, J. Am. Chem. Soc. 2012, 134, 1490.
[15] X-ray crystal data for compound Z-2q: C22H34BNO3; Mr =371.31;
monoclinic space group P21/c; final R indices [I>2s(I)], R1=
0.0731, wR2=0.1831, R indices (all data) R1=0.1207, wR2=0.2091;
a=11.7244(7) ꢁ, b=16.4532(10) ꢁ, c=23.5845(15) ꢁ, a=908, b=
938, g=908; V=4542.8(5) ꢁ3; T=293(2) K; Z=8; reflections col-
lected/unique 26217/8454 [RACTHUNRTGNEUNG(int)=0.0468], number of observations
[I>2s(I)] 5100, parameters: 587. CCDC-881471 contains the supple-
mentary crystallographic data for this paper. These data can be ob-
tained free of charge from The Cambridge Crystallographic Data
Centre via www.ccdc.cam.ac.uk/data_request/cif.
[16] DFT calculations were performed to investigate why the degree of
regiocontrol achieved with the amide derivative substrate was supe-
rior to that of the ester derivative substrate. For details see the Sup-
porting Information.
[17] J. M. Murphy, X. Liao, J. F. Hartwig, J. Am. Chem. Soc. 2007, 129,
15434.
[18] T. Ohe, N. Miyaura, A. Suzuki, J. Org. Chem. 1993, 58, 2201.
[19] All calculations were performed with the Gaussian 09 package of
programs. The calculations were carried out with the B3LYP func-
tional, by using 6–31G[d] basis set for C, H, O, N, B, and P, and
LANL2TZ pseudopotential for Cu. Computational details and refer-
ences are given in the Supporting Information.
[20] The relative free energies and relative electronic energies are similar
in cases in which the number of reactant and product molecules are
equal, but differ significantly for the two-to-one or one-to-two trans-
formations because of entropic contributions. In this paper, relative
free energies are used to analyze the reaction mechanism.
Received: August 8, 2012
Revised: December 12, 2012
Published online: April 4, 2013
7202
www.chemeurj.org
ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2013, 19, 7193 – 7202