Nickel(II) Catalyzed Hydroboration: A Route to Selective Reduction of Aldehydes and N-Allylimines

Article abstract of DOI:10.1002/ejic.202000092

A cationic [(iminophosphine)nickel(allyl)]⁺ complex was found to be sufficiently electrophilic to activate aldehydes and N-allylimines to undergo hydroboration with pinacolborane (HBpin) under mild reaction conditions. The catalyst displayed excellent selectivity toward aldehydes in the presence of ketones. A wide variety of functional groups were tolerated, including halogens, NO₂, CN, OMe, and alkenes for both aldehydes and imines. Electron-rich substrates were found to be significantly more reactive than their electron poor counterparts, a feature that was correlated to their enhanced ability to coordinate to the Lewis acidic nickel center.

Full text of DOI:10.1002/ejic.202000092

European Journal of Inorganic Chemistry
Accepted Article
Title: Nickel(II) Catalyzed Hydroboration: A Route to Selective
Reduction of Aldehydes and N-Allylimines
Authors: Istiak Hossain and Joseph A Schmidt
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To be cited as: Eur. J. Inorg. Chem. 10.1002/ejic.202000092
Link to VoR: https://doi.org/10.1002/ejic.202000092
01/2020

10.1002/ejic.202000092
European Journal of Inorganic Chemistry
FULL PAPER
Nickel(II) Catalyzed Hydroboration: A Route to Selective
Reduction of Aldehydes and N-Allylimines
Istiak Hossain,[a] and Joseph A. R. Schmidt*[a]
[a] Prof. Dr. Joseph A. R. Schmidt
Department of Chemistry and Biochemistry, School of Green Chemistry and Engineering,
College of Natural Sciences and Mathematics, The University of Toledo.
2801 W. Bancroft St. MS 602, Toledo, Ohio, 43606-3390, USA
Phone: (419) 530-1512
Fax: (419) 530-4033
Email: joseph.schmidt@utoledo.edu
Supporting information for this article is given via a link at the end of the document.
Abstract: A cationic [(iminophosphine)nickel(allyl)]+ complex was
found to be sufficiently electrophilic to activate aldehydes and N-
allylimines to undergo hydroboration with pinacolborane (HBpin)
under mild reaction conditions. The catalyst displayed excellent
selectivity toward aldehydes in the presence of ketones. A wide
variety of functional groups were tolerated, including halogens,
NO2, CN, OMe, and alkenes for both aldehydes and imines.
Electron-rich substrates were found to be significantly more
reactive than their electron poor counterparts, a feature that was
correlated to their enhanced ability to coordinate to the Lewis
acidic nickel center.
proceeded with almost equal efficiency for ketones, aldehydes,
and imines. Recently, a couple of reports have also been
published employing nickel for hydroboration of carbon
dioxide[23] and N-heteroarenes.[24]
Inspired by these studies we were intrigued to employ our
recently synthesized cationic nickel(II) allyl complex supported
by an iminophosphine ligand for the hydroboration of carbonyl
and imine compounds. Iminophosphine is
a
bidentate
unsymmetrical ligand having both strong phosphine and weak
imine donor groups (Figure 1). These ligands have proven
successful in several catalytic transformations with nickel.[25]
Herein
we
report
the
utility
of
our
[(iminophosphine)nickel(allyl)]+ (1) complex (Figure 1) as an
efficient catalyst for the hydroboration of aldehydes and N-
allylimines. The catalysis is highly selective towards aldehydes
in the presence of ketones or alkenes. Regarding imines, we
mainly focused on the N-allylimines, to produce N-allylamines,
as they are known to have synthetic utility in organic
synthesis.[26] Also, these substrates were not explored
previously in catalytic hydroboration reactions.
Introduction
Hydroboration is the atom-economic addition of H-B across an
unsaturated bond. This transformation has been used
extensively to produce organo-borates and boranes and as a
means to effect net reduction after basic workup. The resulting
compounds have enormous application in synthetic organic
chemistry.[1] Recently, interest in using hydroboration for the
reduction of carbonyl and imine moieties has increased greatly
due to the mild reaction conditions employed and potential
selectivity observed in multifunctional compounds.[2] The
reduction of carbonyls and imines provides important routes to
alcohols and amines, which are useful compounds both
industrially and in synthetic organic chemistry.[3] Conventional
reducing reagents, such as LiAlH4 and NaBH4, often suffer
from poor yield and low selectivity, especially in the presence
of reducible nitro or cyano groups.[4] Metal-catalyzed
hydrogenation has been studied as an alternative route, but it
requires highly flammable hydrogen gas.[2] In 1939, Brown
reported the utility of diborane (B2H6) as an effective reductant
for carbonyl compounds, but unfortunately diborane also
Figure 1. Iminophosphine ligand and nickel complex (1) utilized in this study.
Results and Discussion
reduces any olefins present.[5] As
a
result catalytic
Initially, an overnight reaction between benzaldehyde and
HBpin was undertaken using 2 mol% of the catalyst 1.
Quantitative formation of the hydroboration product was
hydroboration using less electrophilic boranes has received a
great deal of attention.[2] Known hydroboration catalysts have
been reported using transition metals (Ti,[6] Mo,[7] Fe,[8] Ru,[9]
Co,[10] Ni,[11] Cu[12]), rare-earth metals (La,[13] Yb[14]), main
group elements (Li,[15] Mg,[16] Ca,[17] Zn,[18] Al,[19] Ga,[20] Ge,[21]
Sn[21]), and non-metals.[22] In 2016, Gordon reported nickel-
catalyzed hydroboration,[11] which utilizes a Ni(0) center
supported by a redox active bipyridine ligand. This catalyst
showed high reactivity but poor selectivity as the reaction
1
observed by both H and 11B NMR spectroscopy. Additionally,
we ran a control reaction, in which no catalyst was added. In
this case, less than 10% yield was produced. In order to
optimize the reaction parameters, 4-fluorobenzaldehyde was
chosen as a test compound for ease of monitoring with 19F
NMR spectroscopy (Table 1).
1
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10.1002/ejic.202000092
European Journal of Inorganic Chemistry
FULL PAPER
Table 2. Substrate scope for aldehyde hydroboration[a]
Table 1. Optimization of the Ni(II) catalyzed hydroboration of aldehydes
Entry
Catalyst
(mol%)
Solvent
HBpin
(eq)
1
1
1
1
1
1.1
1.2
1.2
Time
(h)
16
24
24
24
24
6
NMR conv.
(%)a
>99
71
1
2
3
4
5
6
7
8
2
2
2
2
1
1
1
1
Benzene
Chloroform
DCM
ACN
THF
Benzene
Benzene
Toluene
74
42
65
>99
>99
>99
1
1
[a] Conversion measured using in-situ 19F NMR spectroscopy.
A brief search for the optimal reaction solvent was first carried
out. Low yield was observed when using CHCl3 or CH2Cl2
along with significant formation of precipitate. Unsurprisingly,
THF and ACN both did not work well, as we have previously
observed poor efficiency with polar coordinating solvents[25a] in
related hydroamination reactions. With benzene identified as
the best solvent, an increase of HBpin from 1.0 to 1.2
equivalents dramatically increased the efficiency of the
reaction, reducing reaction times and necessary catalyst
loading (entry 7, Table 1). It was also observed that toluene
can serve as a suitable solvent instead of benzene for the
reaction with approximately the same efficiency. Having
identified suitable conditions, a wide range of aldehydes was
subjected to catalytic hydroboration in order to explore
substrate scope (Table 2). Note that for all entries in Table 2,
the time given represents the reaction period necessary to
achieve essentially quantitative conversion, as observed by
NMR spectroscopy. A variety of aromatic aldehydes containing
both electron-withdrawing and donating groups in the different
positions were tested. Each of the electron-rich substrates
proceeded with almost equal efficiency (1a-d). For trans-
cinnamaldehyde, only the aldehyde moiety was reduced,
leaving its C=C bond intact to produce 1e. No significant steric
inhibition effects were observed for ortho-substituted
substrates giving 1g, 1h, and 1i. Additionally, ester, nitrile, and
alkene groups were retained under the reaction conditions to
yield 1h, 1j, and 1m, as shown in Table 2 Furthermore, a furan
ring was also tolerated (1k). In terms of general reactivity, we
were surprised to observe that electron-donating groups
significantly increased the reactivity of the aldehydes in this
transformation. Notably, cyclohexanecarboxaldehyde and 4-
methoxybenzaldehyde were converted to 1a and 1d within 15
min, whereas -F and -CF3 substituted benzaldehydes took
more than an hour to yield 1f and 1l.
[a] Conditions: aldehyde (0.5 mmol), HBpin (1.2 eq), C6D6 (0.8 mL). [b] Yields
were determined by 1H NMR spectroscopy using 1,2,4,5-tetramethylbenzene
as an internal standard. [c] Reaction carried out in THF and isolated yield
reported of the corresponding alcohol.
This finding is in contrast to previous observations with other
transition metals, including cobalt,[10c] iron,[8a] and copper[12b]
catalysts. This sharp contrast in reactivity with other previously
reported systems intrigued us and led us to undertake some
competition experiments with pairs of aldehydes (Table 3).
2
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10.1002/ejic.202000092
European Journal of Inorganic Chemistry
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Table 3. Evaluation of chemoselectivity of carbonyl compounds[a]
reported catalyst that has exhibited better efficiency towards
ketones than aldehydes.[13a] Surprisingly, our catalytic system
is virtually inert toward ketones, making it one of very few
examples where the catalysis is highly chemoselective towards
aldehydes.[8b] For comparison, the more electron rich and more
reactive cyclohexanone, 3c (Table 4), yielded only 40% of the
product after 6 h with 2 mol% catalyst, again demonstrating the
significance of sterics in ketone hydroboration.
Having explored the hydroboration of aldehydes and ketones,
we moved on to a series of imines, especially those with N-allyl
groups, due to their overall synthetic utility. For comparison
with benzaldehyde, the corresponding N-allylbenzaldimine was
tested under the same reaction conditions, and a slower
reaction rate was observed along with significant formation of
precipitate. It was subsequently found that changing solvent
from benzene to the more polar chloroform and increasing to 5
mol% catalyst loading significantly increased the efficiency of
this reaction (Table 5, 2b). The reduction takes place only at
the imine moiety, producing the N-boryl allylamine. Various
substituents on the benzene ring were tested including
halogens, nitro, and cyano groups (Table 5).
Table 5. Substrate scope for N-allylimine hydroboration[a]
[a]
Yields are based on 1H NMR spectroscopy using 1,2,4,5-
tetramethylbenzene as an internal standard.
As we had observed individually, we found a preference for
electron-rich aldehydes: benzaldehyde was preferred over 4-
fluorobenzaldehyde and cyclohexanecarboxaldehyde was in
turn favored over benzaldehyde. Similar competition
experiments carried out by Findlater with Fe(acac)3 displayed
the
opposite
selectivity,
favoring
electron-deficient
substrates.[8a] Selectivity for electron-rich aldehydes in catalytic
hydroboration is very rare; previously published reports either
did not show any particular selectivity or preferred electron
poor substrates. As briefly mentioned earlier, ketones are
inactive towards this reaction, as observed by 1H NMR
spectroscopy. Experimentally, this chemoselectivity between
aldehyde and ketone was confirmed by a competition reaction
between benzaldehyde and acetophenone, in which the ketone
was left untouched (Table 3C). Even under harsher conditions
(2 mol% catalyst and 60 oC), we did not observe any significant
conversion for 3a or 3b (Table 4).
Table 4. Ketone hydroboration substrates[a]
[a] Conditions: N-allylimine (0.5 mmol), HBpin (1.2 eq), CDCl3 (0.8 mL). [b]
[a] 2 mol% of catalyst 1 utilized.
Yield of the hydrolysed products are reported. [c] Reactions carried out at 40
oC.
The overall reactivity followed a similar trend to that of the
aldehydes, displaying the best rates for electron-rich
substrates yielding 2a-e. Though they were slower overall, no
obvious effect was observed based on the position of the
In general, in this and many other reports, ketones are less
reactive than aldehydes due to both steric and electronic
factors, requiring either higher catalyst loading, longer reaction
times, or higher temperatures.[2] La[N(TMS)2]3 is the only
3
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10.1002/ejic.202000092
European Journal of Inorganic Chemistry
FULL PAPER
halogens (2f-i) on the ring. For strong electron-withdrawing
substituents (-CF3, -NO2), the reaction mixture was heated at
40 0C to obtain better rates (2j, 2l). Unlike the ketones,
ketimines showed reasonable reactivity at high temperature
(Table 5, 2m and 2n). Generally speaking, the slower rate of
imine hydroboration most likely reflects the stronger bonding
between the nitrogen donor atom and the nickel center,
hindering catalyst turnover as compared to that observed for
the related oxygen donor atoms from aldehydes.
color or in 31P NMR spectroscopy was observed. However,
with time the intensity of the 31P NMR resonance decreased,
but even after 20 h we can still see the presence of the starting
catalyst 1. As such it seems that this very sluggish reaction
between 1 and HBPin is too slow to be catalytically relevant.
Overall, from these observations, we believe that our catalysis
proceeds through Lewis acidic activation of the substrates via
coordination to the Ni metal center. Therefore, it is no surprise
that steric bulk on the nitrogen inhibits the reaction. This is also
consistent with the observation that electron-rich substrates
are more reactive, as they have an enhanced ability to
coordinate to the Lewis acidic catalyst. Previously Westcott
reported a similar mechanism for the hydroboration of imines
with a cationic gold complex.[27]
To expand the substrate scope and probe the mechanism, we
also tested other imines with different groups on the iminic
nitrogen (Table 6). It was found that imines having aryl groups
on the iminic nitrogen underwent reduction with moderate
efficiency to yield 4a-4d (Table 6). Interestingly, N-butyl imine
showed excellent reactivity to give 4e (84% yield), a very
similar reactivity to 2b (Table 5); however, the related N-tert-
butyl imine inhibited the reaction completely (4f). From these
observations, we conclude that the pendant double bond in the
allyl group of N-allylimines has no significant effect on the
catalysis, but higher steric demands on the nitrogen can
completely inhibit the reaction.
Scheme 1. Stoichiometric reactions related to possible mechanism
Table 6. Additional imines tested[a]
Conclusion
In conclusion, we have developed a new catalytic system for
hydroboration of both aldehydes and N-allylimines using earth
abundant nickel and mild conditions. The catalyst was found to
be fully selective towards aldehydes in the presence of ketones,
nitriles, alkenes, and halides. For N-allylimine hydroboration, a
wide range of functional groups was also tolerated. The key
feature of this catalysis is that electron-rich substrates are
significantly more reactive. Due to its mild conditions and high
selectivity, this catalyst can be useful for synthetic, medicinal,
and fine chemical synthesis.
[a] Conditions: Imine (0.5 mmol), HBpin (1.2 eq), CH2Cl2 (0.8 mL).
[b] Yield of the hydrolysed products are reported. [c] NMR yield.
From a mechanistic point of view, in hydroboration, the catalyst
usually either activates a substrate through a Lewis acidic
interaction (coordination to the metal) or it activates the B-H
bond by forming
a
metal hydride.[2] We ran several
stoichiometric reactions to investigate the mechanism utilized
in our new nickel system. No interaction was observed
between HBpin and N-allylbenzaldimine by NMR spectroscopy
(Scheme 1). When equimolar amounts of the catalyst (1) and
N-allylbenzaldimine were mixed, the iminic C-H proton peak
broadened significantly, indicating coordination to the nickel.
Furthermore, many of the other signals for N-allylbenzaldimine
also shifted and broadened, most notably the CH2 from the allyl
group, which is also quite proximal to the metal center. When
the same stoichiometric reaction was carried out between
catalyst and N-tert-butyl substituted imine, no broadening of
the iminic-proton resonance was observed. We also monitored
an equimolar reaction between catalyst 1 and HBpin overnight
by 1H and 31P{1H} NMR spectroscopy. Initially no change in
Experimental Section
All reactions were carried out under an inert atmosphere either in a
nitrogen filled glove box or using standard dual manifold Schlenk
techniques. Cationic [(3IP)nickel(II)allyl]+ pre-catalyst 1 was synthesized
using the previously published procedure from our lab.[25a] All
substrates and solvents used for this catalysis were dried and
degassed before transferring into the glove box. Deuterated chloroform
and benzene (Cambridge Isotope Laboratories) were dried using
calcium hydride and sodium metal, respectively, and degassed via
three freeze-pump-thaw cycles. These solvents were distilled under
vacuum and stored over activated 4 Å molecular sieves inside the glove
box. Aldehydes and allylamine were purchased either from Alfa Aesar,
AK Scientific, or Acros Organics. All liquid aldehydes were dried over 4
Å molecular sieves and distilled under vacuum before use. Solid
4
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10.1002/ejic.202000092
European Journal of Inorganic Chemistry
FULL PAPER
compounds were dried under vacuum. 2-Acetoxybenzaldehyde[28] and
4-vinylbenzaldehyde[29] were synthesized using published procedures.
Imines were synthesized using Schiff base reactions with the
corresponding aldehydes and amines and their spectroscopic data
matched the reported values.[30] Synthesized imines were dried with
calcium hydride and then distilled off or filtered over celite under
nitrogen. Pinacolborane (HBpin) was purchased from Acros Organics
and used without further purification.
136.9, 129.3, 127.3, 82.7, 66.9, 24.7, 21.1. 11B NMR (128 MHz, C6D6):
23.00
2-(4-Methoxybenzyloxy)pinacolborane (1d).[31] 1H NMR (600 MHz,
C6D6): δ 7.25 (d, 3JHH = 8.5 Hz, 2H), 6.74 (d, 3JHH = 8.5 Hz, 2H), 4.92 (s,
2H), 3.30 (s, 3H), 1.05 (s, 12H). 13C{1H} NMR (151 MHz, C6D6): δ 159.6,
132.1, 128.8, 114.1, 82.7, 66.8, 54.7, 24.4. 11B NMR (128 MHz, C6D6):
22.95.
Characterization: All 1H and 13C{1H} NMR data were collected using a
600 MHz Varian Inova spectrometer at 599.9 MHz and 150.8 MHz,
respectively. 11B NMR data were obtained from a 400 MHz Varian
spectrometer at 128 MHz. 1H NMR spectra were referenced using the
residual proton resonance of the deuterated solvent (7.16 ppm in C6D6,
7.26 ppm in CDCl3). 13C{1H} NMR were also referenced at 128.06 and
77.16 ppm in benzene and chloroform, respectively. 11B NMR were
externally referenced to a BF3·OEt2 standard.
2-(Cinnamyloxy)pinacolborane (1e).[32] 1H NMR (600 MHz, C6D6): δ
3
3
3
7.17 (d, JHH = 7.4 Hz, 2H), 7.08 (t, JHH = 7.4 Hz, 2H), 7.01 (t, JHH
=
=
3
4
3
7.4 Hz, 1H), 6.59 (dt, JHH = 16.0, JHH = 1.8 Hz, 1H), 6.16 (dt, JHH
16.0, 3JHH = 5.2 Hz, 1H), 4.52 (dd, 3JHH = 5.2, 4JHH = 1.8 Hz, 2H), 1.06 (s,
12H). 13C{1H} NMR (151 MHz, C6D6) δ 137.3, 130.8, 128.8, 127.7,
127.5, 126.8, 82.7, 65.5, 24.7. 11B NMR (128 MHz, C6D6): 22.85.
2-(4-Fluorobenzyloxy)pinacolborane (1f).[33] 1H NMR (600 MHz, C6D6):
δ 7.10 – 7.04 (m, 2H), 6.80 – 6.73 (m, 2H), 4.79 (s, 2H), 1.04 (s, 12H).
1
13C{1H} NMR (151 MHz, C6D6): δ 162.6 (d, JCF = 244.6 Hz), 135.8 (d,
Procedure for the Catalytic Hydroboration of Aldehydes: In the
glove box, 31.6 mg (0.05 mmol) of the pre-catalyst (1) was transferred
to a 1.0 mL volumetric flask and C6D6 was added to reach the mark. In
a typical experiment, aldehyde (0.5 mmol) was transferred into a 10 ml
vial followed by 600 µL of deuterated benzene. Then, 100 µL (0.005
mmol) of the pre-catalyst stock solution was added followed by 1,2,4,5-
tetramethylbenzene (0.1 mmol) as an internal standard. The mixture
was transferred to an NMR tube. Finally, HBpin (86 µL, 1.2 eq) was
added and the NMR tube was removed from the glove box. The
reaction was then monitored by 1H NMR spectroscopy. The NMR yields
were calculated using actual masses of the internal standard
transferred. Previously reported boryl esters were characterized using
1H, 13C{1H}, and 11B NMR and matched with the literature data. For new
boryl esters (1h, 1l, and 1m), compounds were hydrolyzed to the
2
4JCF = 3.3 Hz), 128.9 (d, 3JCF = 8.0 Hz), 115.3 (d, JCF = 21.4 Hz), 82.8,
66.2, 24.7. 11B NMR (128 MHz, C6D6): 22.84.
2-(2-Chlorobenzyloxy)pinacolborane (1g).[34] 1H NMR (600 MHz, C6D6):
δ 7.54 (d, 3JHH = 7.8 Hz, 1H), 7.07 (d, 3JHH = 7.8 Hz, 1H), 6.92 (t, 3JHH
7.8 Hz, 1H), 6.78 (t, JHH = 7.8 Hz, 1H), 5.13 (s, 2H), 1.04 (s, 12H).
13C{1H} NMR (600 MHz, C6D6): δ 137.5, 132.2, 129.3, 128.5, 127.9,
127.0, 82.9, 64.4, 24.7. 11B NMR (128 MHz, C6D6): 22.93.
=
3
2-(2-Acetylbenzyloxy)pinacolborane (1h). 1H NMR (600 MHz, C6D6): δ
3
7.54 (d, JHH = 7.2 Hz, 1H), 7.04 – 6.94 (m, 3H), 5.02 (s, 2H), 1.77 (s,
3H), 1.02 (s, 12H). 13C{1H} NMR (151 MHz, C6D6): δ 168.3, 148.7,
131.9, 128.54, 128.52, 126.1, 122.6, 82.9, 62.4, 24.6, 20.3. 11B NMR
(128 MHz, C6D6): 22.88.
corresponding alcohol for characterization.
For hydrolysis, after
completion of the reaction, solvent was removed under vacuum and
then 1 ml of methanol was added and stirred for 30 min at room
temperature. The product was then purified with flash column
chromatography using hexane/ethyl acetate mixture (85/15) as an
eluent. For 1n, the reaction was run in non-deuterated THF and only
the hydrolyzed product is reported.
2-(Hydroxymethyl)phenyl acetate (1h’).[35] Colorless oily liquid (64 mg,
1
77% isolated yield). H NMR (600 MHz, CDCl3): δ 7.80 (s, 1H), 7.32 –
7.25 (m, 2H), 6.98 – 6.89 (m, 2H), 5.13 (s, 2H), 2.12 (s, 3H). 13C{1H}
NMR (151 MHz, C6D6): δ 173.9, 155.7, 132.4, 131.3, 121.7, 120.7,
118.0, 63.4, 21.1.
Procedure for the Catalytic Hydroboration of Imines: In the glove
box, 16 mg (0.025 mmol) of the pre-catalyst was placed in a 10 ml vial.
Imine (0.5 mmol) was added followed by 600 µL of deuterated
chloroform or dichloromethane. Then, HBpin was added (86 µL, 1.2 eq)
using an automatic pipet. The solution was thoroughly mixed and
transferred to an NMR tube and frequently observed via 1H NMR
spectroscopy. After completion (>95%) of the reaction, solvent was
removed under vacuum and then 1 ml of methanol was added and
stirred for 30 min to hydrolyze the compound. The product was then
purified with flash column chromatography using hexane/ethyl
acetate/triethyl amine (80/20/1) as a mobile phase. Also, note that TLC
plates were made basic with 2% Et3N (in hexane) solution to make the
amine compound visible.
2-(2-Bromobenzyloxy)pinacolborane (1i).[33] 1H NMR (600 MHz, C6D6):
δ 7.54 (d, 3JHH = 7.5 Hz, 1H), 7.26 (d, 3JHH = 7.5 Hz, 1H), 6.96 (t, 3JHH
=
3
7.5 Hz, 1H), 6.70 (t, JHH = 7.5 Hz, 1H), 5.09 (s, 2H), 1.04 (s, 12H).
13C{1H} NMR (151 MHz, C6D6): δ 139.0, 132.5, 128.8, 128.0, 127.6,
121.8, 83.0, 66.6, 24.7. 11B NMR (128 MHz, C6D6): 22.92.
2-(4-Cyanobenzyloxy)pinacolborane (1j).[34] 1H NMR (600 MHz, C6D6):
3
δ 7.03 (d, 3JHH = 7.0 Hz, 2H), 6.90 (d, JHH = 7.0 Hz, 2H), 4.67 (s, 2H),
1.05 (s, 12H). 13C{1H} NMR (151 MHz, C6D6): δ 144.6, 133.6, 132.1,
131.4, 126.8, 83.1, 65.8, 24.7. 11B NMR (128 MHz, C6D6): 22.77.
2-(Furfuryloxy)pinacolborane (1k).[31] 1H NMR (600 MHz, C6D6): δ 7.07
– 7.06 (m, 1H), 6.13 (d, 3JHH = 3.3 Hz, 1H), 6.05 – 6.00 (m, 1H), 4.83 (s,
2H), 1.03 (s, 12H).13C{1H} NMR (151 MHz, C6D6): δ 153.3, 142.6, 110.5,
108.5, 82.8, 59.4, 24.7. 11B NMR (128 MHz, C6D6): 22.87.
Characterization of Hydroboration Products
2-(Cyclohexylmethoxy)pinacolborane (1a).[31] 1H NMR (600 MHz,
C6D6): δ 3.75 (d, JHH = 6.5 Hz, 2H), 1.72 – 1.69 (m, 2H), 1.62 – 1.58
(m, 2H), 1.55 – 1.46 (m, 2H), 1.17 – 1.10 (m, 3H), 1.07 (s, 12H), 0.93 –
0.86 (m, 2H). 13C{1H} NMR (151 MHz, C6D6): δ 82.4, 70.6, 39.8, 29.7,
26.8, 26.2, 24.8. 11B NMR (128 MHz, C6D6): 22.63.
3
2-(3-Trifluoromethylbenzyloxy)pinacolborane (1l). 1H NMR (600 MHz,
C6D6): δ 7.56 (s, 1H), 7.24 (d, 3JHH = 7.6 Hz, 1H), 7.20 (d, 3JHH = 7.6 Hz,
3
1H), 6.92 (t, JHH = 7.6 Hz, 1H), 4.75 (s, 2H), 1.04 (s, 12H). 13C{1H}
NMR (151 MHz, C6D6): δ 141.0, 130.8 (q, 2JCF = 32.0 Hz), 130.2, 129.1,
124.9 (q, 1JCF = 271.8 Hz), 124.3 (q, 3JCF = 3.8 Hz), 123.7 (q, 3JCF = 3.8
Hz), 83.1, 66.1, 24.6. 11B NMR (128 MHz, C6D6): 22.87.
2-(Benzyloxy)pinacolborane (1b).[31] 1H NMR (600 MHz, C6D6): δ 7.30
(d, 3JHH = 7.5 Hz, 2H), 7.13 (t, 3JHH = 7.5 Hz, 2H), 7.05 (t, 3JHH = 7.5 Hz,
1H), 4.94 (s, 2H), 1.04 (s, 12H). 13C{1H} NMR (151 MHz, C6D6): δ 140.0,
128.6, 127.6, 127.0, 82.7, 66.9, 24.7. 11B NMR (128 MHz, C6D6): 22.96.
(3-(Trifluoromethyl)phenyl)methanol (1l’).[36] Colorless liquid (76 mg,
86% isolated yield). 1H NMR (600 MHz, CDCl3): δ 7.64 (s, 1H), 7.55-
7.54 (m, 2H), 7.49-7.46 (m, 1H), 4.77 (s, 2H), 1.88 (br s, 1H). 13C{1H}
NMR (151 MHz, CDCl3) δ 141.7, 130.9 (q, 2JCF = 32.2 Hz), 130.0, 129.1,
124.5 (q, 3JCF = 3.8 Hz), 124.1 (q, 1JCF = 272.4 Hz), 123.5 (q, 3JCF = 3.8
Hz), 64.6.
2-(4-Methylbenzyloxy)pinacolborane (1c).[31] 1H NMR (600 MHz, C6D6):
3
δ 7.25 (d, 3JHH = 7.8 Hz, 2H), 6.97 (d, JHH = 7.8 Hz, 2H), 4.95 (s, 2H),
2.09 (s, 3H), 1.05 (s, 12H). 13C{1H} NMR (151 MHz, C6D6): δ 137.1,
5
This article is protected by copyright. All rights reserved.

10.1002/ejic.202000092
European Journal of Inorganic Chemistry
FULL PAPER
2-(4-Vinylbenzyloxy)pinacolborane (1m). 1H NMR (600 MHz, C6D6): δ
N-(4-Fluorobenzyl)prop-2-en-1-amine (2f).[30a] Colorless liquid (71 mg,
7.25 (d, 3JHH = 8.0 Hz, 2H), 7.20 (d, 3JHH = 8.0 Hz, 2H), 6.55 (dd, 3JHH
=
=
86% isolated yield). H NMR (600 MHz, CDCl3): δ 7.32 – 7.27 (m, 2H),
1
3
3
3
3
17.6, JHH = 10.9 Hz, 1H), 5.57 (d, JHH = 17.6 Hz, 1H), 5.05 (d, JHH
7.04 – 6.98 (m, 2H), 5.92 (ddt, JHH = 17.1, 3JHH = 10.2, 3JHH = 5.9 Hz,
10.9 Hz, 1H), 4.93 (s, 2H), 1.04 (s, 12H). 13C{1H} NMR (151 MHz,
C6D6): δ 139.7, 137.09, 137.06, 127.3, 126.6, 113.5, 82.8, 66.7, 24.7.
11B NMR (128 MHz, C6D6): 22.95.
1H), 5.19 (dq, JHH = 17.1, 4JHH = JHH = 1.4 Hz, 1H), 5.12 (dq, JHH
=
=
3
2
3
10.2, 4JHH = 2JHH = 1.4 Hz, 1H), 3.75 (s, 2H), 3.26 (dt, 3JHH = 5.9, 4JHH
1.4 Hz, 2H), 1.42 (br s, 1H). 13C{1H} NMR (151 MHz, CDCl3): δ 162.0 (d,
1JCF = 244.5 Hz), 136.8, 136.1 (d, JCF = 3.1 Hz), 129.8 (d, JCF = 7.9
4
3
Hz), 116.3, 115.3 (d, 2JCF = 21.3 Hz), 52.6, 51.8.
(4-Vinylphenyl)methanol (1m’).[37] Colorless liquid (54 mg, 80% isolated
yield). 1H NMR (600 MHz, CDCl3): δ 7.41 (d, JHH = 8.2 Hz, 2H), 7.33
3
3
3
(d, JHH = 8.2 Hz, 2H), 6.72 (dd, JHH = 17.6, 3JHH = 10.9 Hz, 1H), 5.76
N-(4-Chlorobenzyl)prop-2-en-1-amine (2g).[41] Colorless liquid (80 mg,
(d, 3JHH = 17.6 Hz, 1H), 5.25 (d, JHH = 10.9 Hz, 1H), 4.68 (s, 2H), 1.74
88% isolated yield). H NMR (600 MHz, CDCl3): δ 7.27 – 7.22 (m, 4H),
3
1
(br s, 1H). 13C{1H} NMR (151 MHz, CDCl3): δ 140.5, 137.1, 136.6,
5.88 (ddt, JHH = 17.2, 3JHH = 10.4, JHH = 6.0 Hz, 1H), 5.16 (dq, JHH
=
3
3
3
3
2
127.3, 126.5, 114.1, 65.2.
17.2, 4JHH = 2JHH = 1.4 Hz, 1H), 5.09 (dq, JHH = 10.4, 4JHH = JHH = 1.4
Hz, 1H), 3.73 (s, 2H), 3.23 (dt, 3JHH = 6.0, 4JHH = 1.4 Hz, 2H), 1.41 (br s,
1H). 13C{1H} NMR (151 MHz, CDCl3): δ 138.8, 136.7, 132.7, 129.6,
128.6, 116.3, 52.5, 51.8.
(4-Nitrophenyl)methanol (1n’).[38] Light yellow solid (63 mg, 82%
isolated yield). 1H NMR (600 MHz, CDCl3): δ 8.23 (d, JHH = 8.8 Hz,
3
3
2H), 7.55 (d, JHH = 8.8 Hz, 2H), 4.85 (s, 2H), 1.78 (br s, 1H). 13C{1H}
NMR (151 MHz, CDCl3): δ 148.3, 147.4, 127.1, 123.9, 64.2.
N-(3-Bromobenzyl)prop-2-en-1-amine (2h).[30a] Colorless liquid (94 mg,
84% isolated yield). 1H NMR (600 MHz, CDCl3): δ 7.50 (s, 1H), 7.38 (d,
3
3
3JHH = 7.7 Hz, 1H), 7.25 (d, JHH = 7.7 Hz, 1H), 7.19 (t, JHH = 7.7 Hz,
4,4,5,5-Tetramethyl-2-(pentyloxy)-1,3,2-dioxaborolane (1o).[33] 1H NMR
3
3
3
3
1H), 5.92 (ddt, JHH = 17.0, JHH = 10.4, JHH = 6.0 Hz, 1H), 5.20 (dq,
(600 MHz, C6D6): δ 3.91 (t, JHH = 6.6 Hz, 2H), 1.56 – 1.49 (m, 2H),
3JHH = 17.0, 4JHH = 2JHH = 1.6 Hz, 1H), 5.13 (dq, JHH = 10.4, 4JHH = 2JHH
3
1.28 – 1.16 (m, 4H), 1.07 (s, 12H), 0.80 (t, JHH = 7.2 Hz, 3H). 13C{1H}
3
= 1.6 Hz, 1H), 3.76 (s, 2H), 3.26 (dt, 3JHH = 6.0, 4JHH = 1.6 Hz, 2H), 1.49
(br s, 1H). 13C{1H} NMR (151 MHz, CDCl3): δ 142.8, 136.6, 131.3,
130.2, 130.1, 126.9, 122.6, 116.4, 52.7, 51.8.
NMR (151 MHz, C6D6): δ 82.4, 65.1, 31.7, 28.2, 24.7, 22.7, 14.2. 11B
NMR (128 MHz, C6D6): δ 22.66.
N-(Cyclohexylmethyl)prop-2-en-1-amine (2a).[39] Colorless liquid (58 mg,
76% isolated yield). 1H NMR (600 MHz, CDCl3): δ 5.90 (ddt, 3JHH = 17.0,
N-(2-Bromobenzyl)prop-2-en-1-amine (2i).[42] Colorless liquid (97 mg,
86% isolated yield). H NMR (600 MHz, CDCl3): δ 7.54 (dd, JHH = 7.8,
1
3
3
3
4
3JHH = 10.2, JHH = 6.0 Hz, 1H), 5.16 (dq, JHH = 17.0, JHH
=
2JHH = 1.6
3
4
4JHH = 1.4 Hz, 1H), 7.38 (dd, JHH = 7.8, JHH = 1.4 Hz, 1H), 7.28 (td,
Hz, 1H), 5.07 (dq, 3JHH = 10.2, 4JHH = 2JHH = 1.6 Hz, 1H), 3.22 (dt, 3JHH
=
3JHH = 7.8, JHH = 1.4 Hz, 1H), 7.12 (td, JHH = 7.8, JHH = 1.4 Hz, 1H),
4
3
4
6.0, 4JHH = 1.6 Hz, 2H), 2.43 (d, 3JHH = 6.7 Hz, 2H), 1.77 – 1.62 (m, 5H),
1.49 – 1.40 (m, 1H), 1.29 – 1.10 (m, 4H), 0.95 – 0.83 (m, 2H). 13C{1H}
NMR (151 MHz, CDCl3): δ 137.3, 115.8, 56.4, 52.9, 38.2, 31.6, 26.8,
26.2.
5.94 (ddt, JHH = 17.2, 3JHH = 10.2, 3JHH = 6.0 Hz, 1H), 5.22 (dq, JHH
=
3
3
17.2, 4JHH = 2JHH = 1.6 Hz, 1H), 5.12 (dq, JHH = 10.2, 4JHH = JHH = 1.6
Hz, 1H), 3.86 (s, 2H), 3.27 (dt, 3JHH = 6.0, 4JHH = 1.6 Hz, 2H), 1.64 (br s,
1H). 13C{1H} NMR (151 MHz, CDCl3): δ 139.2, 136.8, 132.9, 130.5,
128.7, 127.5, 124.1, 116.3, 53.2, 51.7.
3
2
N-Benzylprop-2-en-1-amine (2b).[40] Colorless liquid (60 mg, 81%
isolated yield). 1H NMR (600 MHz, CDCl3): δ 7.33 – 7.30 (m, 4H), 7.25
N-(3-(Trifluoromethyl)benzyl)prop-2-en-1-amine (2j).[30a] Colorless liquid
3
3
– 7.22 (m, 1H), 5.92 (ddt, JHH = 17.2, JHH = 10.2, 3JHH = 6.0 Hz, 1H),
(92 mg, 85% isolated yield). 1H NMR (600 MHz, CDCl3): δ 7.60 (s, 1H),
5.19 (dq, JHH = 17.2, 4JHH
=
2JHH = 1.5 Hz, 1H), 5.10 (dq, JHH = 10.2,
3
3
3
7.53 – 7.50 (m, 2H), 7.45 – 7.42 (m, 1H), 5.92 (ddt, JHH = 16.8, 3JHH
=
4JHH
=
2JHH = 1.5 Hz, 1H), 3.78 (s, 2H), 3.27 (dt, JHH = 6.0, JHH = 1.5
3
4
10.2, 3JHH = 6.0 Hz, 1H), 5.21 (dq, 3JHH = 16.8, 4JHH = 2JHH = 1.4 Hz, 1H),
Hz, 2H), 1.47 (br s, 1H). 13C{1H} NMR (151 MHz, CDCl3): δ 140.3,
3
4
5.13 (dq, JHH = 10.2, JHH
=
2JHH = 1.4 Hz, 1H), 3.85 (s, 2H), 3.28 (dt,
136.9, 128.5, 128.3, 127.1, 116.1, 53.4, 51.9.
3JHH = 6.0, 4JHH = 1.4 Hz, 2H), 1.49 (br s, 1H). 13C{1H} NMR (151 MHz,
2
CDCl3): 141.4, 136.6, 131.6, 130.8 (q, JCF = 32.3 Hz), 128.9, 125.0 (q,
N-(4-Methylbenzyl)prop-2-en-1-amine (2c).[30a] Colorless liquid (74 mg,
3JCF = 3.8 Hz), 124.3 (q, 1JCF = 273 Hz), 123.9 (q, 3JCF = 3.8 Hz), 116.5,
3
92% isolated yield). 1H NMR (600 MHz, CDCl3): δ 7.22 (d, JHH = 7.9
52.8, 51.9.
Hz, 2H), 7.15 (d, 3JHH = 7.9 Hz, 2H), 5.94 (ddt, 3JHH = 17.2, 3JHH = 10.2,
3JHH = 6.0 Hz, 1H), 5.20 (dq, 3JHH = 17.2, 4JHH = 2JHH = 1.6 Hz, 1H), 5.12
N-(4-Cyanobenzyl)prop-2-en-1-amine (2k).[30a] Colorless liquid (73 mg,
(dq, 3JHH = 10.2, 4JHH = 2JHH = 1.6 Hz, 1H), 3.76 (s, 2H), 3.28 (dt, 3JHH
=
3
85% isolated yield). 1H NMR (600 MHz, CDCl3): δ 7.61 (d, JHH = 8.0
6.0, 4JHH = 1.6 Hz, 2H), 2.35 (s, 3H), 1.52 (br s, 1H). 13C{1H} NMR (151
MHz, CDCl3): δ 137.2, 136.9, 136.6, 129.2, 128.2, 116.1, 53.1, 51.8,
21.2.
Hz, 2H), 7.45 (d, 3JHH = 8.0 Hz, 2H), 5.93 – 5.83 (m, 1H), 5.20 (dm, 3JHH
3
= 17.2 Hz, 1H), 5.13 (dm, JHH = 10.3 Hz, 1H), 3.83 (s, 2H), 3.26 (dm,
3JHH = 5.8 Hz, 2H), 1.34 (br s, 1H). 13C{1H} NMR (151 MHz, CDCl3): δ
146.1, 136.5, 132.4, 128.8, 119.1, 116.5, 110.8, 52.7, 51.9.
N-(4-Methoxybenzyl)prop-2-en-1-amine (2d).[41] Colorless liquid (81 mg,
3
91% isolated yield). 1H NMR (600 MHz, CDCl3): δ 7.24 (d, JHH = 8.3
N-(4-Nitrobenzyl)prop-2-en-1-amine (2l).[43] Yellow liquid (78 mg, 81%
isolated yield). 1H NMR (600 MHz, CDCl3): δ 8.16 (d, 3JHH = 8.4 Hz, 2H),
Hz, 2H), 6.86 (d, 3JHH = 8.3 Hz, 2H), 5.93 (ddt, 3JHH = 17.3, 3JHH = 10.4,
3JHH = 6.0 Hz, 1H), 5.19 (dq, 3JHH = 17.3, 4JHH = 2JHH = 1.6 Hz, 1H), 5.11
3
3
3
4
(dq, JHH = 10.4, JHH
=
2JHH = 1.6 Hz, 1H), 3.79 (s, 3H), 3.73 (s, 2H),
7.49 (d, JHH = 8.4 Hz, 2H), 5.94 – 5.84 (m, 1H), 5.18 (dm, JHH = 17.2
Hz, 1H), 5.12 (dm, 3JHH = 10.3 Hz, 1H), 3.88 (s, 2H), 3.25 (dt, 3JHH = 6.0,
4JHH = 1.4 Hz, 2H), 1.44 (br s, 1H). 13C{1H} NMR (151 MHz, CDCl3): δ
148.3, 147.3, 136.4, 128.8, 123.8, 116.6, 52.5, 51.9.
3.26 (dt, JHH = 6.0, 4JHH = 1.6 Hz, 2H), 1.45 (br s, 1H). 13C{1H} NMR
(151 MHz, CDCl3): δ 158.7, 136.9, 132.5, 129.5, 116.1, 113.8, 55.4,
52.8, 51.8.
3
N-(1-(4-Methoxyphenyl)ethyl)prop-2-en-1-amine (2m).[30a]
Colorless
N-(4-N,N-Dimethylaminobenzyl)prop-2-en-1-amine (2e).[30a] Pale yellow
liquid (87 mg, 91% isolated yield). 1H NMR (600 MHz, CDCl3): δ 7.20 (d,
liquid (63 mg, 66% isolated yield). 1H NMR (600 MHz, CDCl3): δ 7.23
(d, 3JHH = 8.6 Hz, 2H), 6.87 (d, 3JHH = 8.6 Hz, 2H), 5.88 (ddt, 3JHH = 17.2,
3
3
3JHH = 8.6 Hz, 2H), 6.72 (d, JHH = 8.6 Hz, 2H), 5.94 (ddt, JHH = 16.8,
3
3JHH = 10.2, 3JHH = 6.0 Hz, 1H), 5.12 (dq, JHH = 17.2, 4JHH = 2JHH = 1.6
3
3
4
3JHH = 10.1, JHH = 6.1 Hz, 1H), 5.19 (dq, JHH = 16.8, JHH = 2JHH = 1.6
3
4
2
3
4
Hz, 1H), 5.10 (dq, JHH = 10.1, JHH
=
2JHH = 1.6 Hz, 1H), 3.70 (s, 2H),
Hz, 1H), 5.06 (dq, JHH = 10.2, JHH = JHH = 1.6 Hz, 1H), 3.80 (s, 3H),
3.76 (q, 3JHH = 6.6 Hz, 1H), 3.09 – 3.07 (m, 2H), 1.50 (br s, 1H), 1.34 (d,
3JHH = 6.6 Hz, 3H). 13C{1H} NMR (151 MHz, CDCl3): δ 158.6, 137.6,
137.1, 127.8, 115.9, 113.9, 56.9, 55.4, 50.3, 24.3.
3
4
3.27 (dt, JHH = 6.1, JHH = 1.6 Hz, 2H), 2.94 (s, 6H), 1.38 (br s, 1H).
13C{1H} NMR (151 MHz, CDCl3): δ 149.9, 136.9, 129.2, 128.2, 115.9,
112.7, 52.8, 51.7, 40.8.
6
This article is protected by copyright. All rights reserved.

10.1002/ejic.202000092
European Journal of Inorganic Chemistry
FULL PAPER
N-(1-(4-Chlorophenyl)ethyl)prop-2-en-1-amine (2n).[44] Colorless liquid
2005-2006; c) A. A. Oluyadi, S. Ma, C. N. Muhoro,
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514, 97-102; b) A. Kaithal, B. Chatterjee, C. Gunanathan, J. Org.
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1
(73 mg, 75% isolated yield). H NMR (600 MHz, CDCl3): δ 7.30 – 7.28
[7]
[8]
(m, 2H), 7.26 – 7.24 (m, 2H), 5.87 (ddt, JHH = 17.2, 3JHH = 10.2, 3JHH
=
3
3
4
2
6.0 Hz, 1H), 5.12 (dq, JHH = 17.2, JHH = JHH = 1.6 Hz, 1H), 5.07 (dq,
3JHH = 10.2, 4JHH = 2JHH = 1.6 Hz, 1H), 3.78 (q, JHH = 6.6 Hz, 1H), 3.10
3
– 3.04 (m, 2H), 1.44 (br s, 1H), 1.33 (d, JHH = 6.6 Hz, 3H). 13C{1H}
3
NMR (151 MHz, CDCl3): δ 144.1, 136.8, 132.5, 128.6, 128.1, 115.9,
57.0, 50.3, 24.4
[9]
[10]
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N-(4-Methoxybenzyl)aniline (4a).[45] Light yellow liquid (79 mg, 74%
isolated yield). 1H NMR (600 MHz, CDCl3): δ 7.29 (d, 3JHH = 8.6 Hz, 2H),
3
7.19 – 7.14 (m, 2H), 6.88 (d, JHH = 8.6 Hz, 2H), 6.71 (t, 3JHH = 7.4 Hz,
3
1H), 6.63 (d, JHH = 7.4 Hz, 2H), 4.24 (s, 2H), 3.79 (s, 3H). 13C{1H}
[11]
[12]
[13]
NMR (151 MHz, CDCl3): δ 158.9, 148.3, 131.5, 129.4, 128.9, 117.6,
114.1, 112.9, 55.4, 47.9.
N-Benzyl-4-fluoroaniline (4b).[45] Light yellow liquid (69 mg, 68%
isolated yield). 1H NMR (600 MHz, CDCl3): δ 7.42 – 7.35 (m, 4H), 7.34
– 7.29 (m, 1H), 6.96 – 6.82 (m, 2H), 6.64 – 6.54 (m, 2H), 4.32 (s, 2H).
1
13C{1H} NMR (151 MHz, CDCl3): δ 156.0 (d, JCF = 234.9 Hz), 144.6,
[14]
[15]
2
3
139.3, 128.8, 127.6, 127.5, 115.8 (d, JCF = 22.5 Hz), 113.8 (d, JCF
=
7.3 Hz), 49.1.
N-Cinnamylaniline (4c).[46] Light yellow solid (65 mg, 62% isolated yield).
1H NMR (600 MHz, CDCl3): δ 7.41 (d, 3JHH = 7.5 Hz, 2H), 7.34 (t, 3JHH
7.5 Hz, 2H), 7.28 – 7.21 (m, 3H), 6.76 (t, JHH = 7.4 Hz, 1H), 6.71 (d,
=
[16]
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Cozzi, Angew. Chem. 2003, 115, 5078-5080.
3
3
3
3JHH = 7.4 Hz, 2H), 6.66 (d, JHH = 15.9 Hz, 1H), 6.37 (dt, JHH = 15.9,
[17]
[18]
3JHH = 5.8 Hz, 1H), 3.98 (dd, JHH = 5.8, JHH = 1.5 Hz, 2H). 13C{1H}
NMR (151 MHz, CDCl3): δ 148.2, 137.0, 131.7, 129.4, 128.7, 127.7,
127.2, 126.5, 117.8, 113.2, 46.4.
3
4
[19]
[20]
[21]
[22]
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3857.
Dibenzylamine (4d).[47] Light yellow liquid (81 mg, 82% isolated yield).
1H NMR (600 MHz, CDCl3): δ 7.36 – 7.30 (m, 8H), 7.27 – 7.23 (m, 2H),
3.80 (s, 4H). 13C{1H} NMR (151 MHz, CDCl3): δ 140.4, 128.5, 128.3,
127.1, 53.3.
N-Benzylbutan-1-amine (4e).[48] Colorless liquid (69 mg, 84% isolated
yield). 1H NMR (600 MHz, CDCl3): δ 7.32 – 7.28 (m, 4H), 7.24 – 7.21
3
(m, 1H), 3.77 (s, 2H), 2.65 – 2.57 (m, 2H), 1.48 (p, JHH = 7.4 Hz, 2H),
1.36 – 1.29 (m, 2H), 0.89 (t, 3JHH = 7.4 Hz, 3H). 13C{1H} NMR (151 MHz,
CDCl3): δ 133.4, 129.3, 128.9, 128.6, 52.2, 47.3, 29.3, 19.9, 13.4.
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This work was supported by The University of Toledo via a
Summer Research Award.
Keywords: Aldehyde • Hydroboration • Imine • Nickel •
Reduction
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Entry for the Table of Contents
Catalytic Hydroboration
The hydroboration activity of a cationic [(iminophosphine)nickel(allyl)]+ complex towards aldehydes and imines has been reported.
The catalyst showed excellent functional group tolerance toward alkenes, nitriles, and halides. Its reactivity was greatest for
aldehydes and moderate for imines, while it was virtually unreactive with ketones.
9
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