4
Tetrahedron
ACCEPTED MANUSCRIPT
4. Experimental section
In a N2 filled glovebox, NaBHEt3 (5 µL, 1 M in THF, 5 µmol,
0.02 mol%) was added to a mixture of B2pin2 (25 mmol) and
complex 1 (1.1 mg, 2.5 µmol, 0.01 mol%) in Et2O (12 mL) at 25
ºC in a 100 mL tube equipped with a magnetic stir bar. After the
mixture was stirred for minutes, the color was changed from
colorless to purple. The reaction tube was then placed in an
autoclave. The autoclave was closed, purged three times with D2
(less than the pressure needed). The reaction mixture was stirred
at 25 ºC under D2 atmosphere (15 bar) for 9 h. After release part
of gas, an autoclave was opened in a N2 filled glovebox. The
reaction mixture was transferred to a 100 mL flask equipped with
a magnetic stir bar. The Et2O solvent was removed via distillation
under 1 atm of argon. Pure DBpin was obtained by vacuum
transfer (4.77 g, 74%) as a clear, colorless liquid into an oven-
Unless otherwise noted, all reagents were purchased from
commercial suppliers and used without further purification. All
manipulations were carried out using standard Schlenk, high-
vacuum and glovebox techniques. Ethyl ether (Et2O), pentane,
tetrahydrofuran (THF), toluene were distilled from sodium
benzophenone ketyl prior to use. Alkenes and alkynes are were
purchased from TCI, J&K, Aldrich and Alfa and were used as
received. (tBuPNN)CoCl2 was synthesized according to our
previously reported procedure.11c
NMR spectra were recorded on Agilent 400 MHz or Bruker
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400 MHz or Agilent 600 MHz. H NMR chemical shifts were
referenced to residual protio solvent peaks or tetramethylsilane
signal (0 ppm), and 13C NMR chemical shifts were referenced to
the solvent resonance. Data for 1H NMR are recorded as follows:
chemical shift (δ, ppm), multiplicity (s = singlet, d = doublet, t =
triplet, m = multiplet or unresolved, coupling constant (s) in Hz,
integration). Data for 13C NMR are reported in terms of chemical
shift (δ, ppm). The carbon bearing the boron is missing for all
hydroboration products in the 13C NMR spectra. GC analysis was
acquired on Agilent 7820A gas chromatograph equipped with a
flame-ionization detector. Elemental analyses and high resolution
mass spectrometer (HR-MS) were carried out by the Analytical
Laboratory of Shanghai Institute of Organic Chemistry (CAS).
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dried, 50 mL flask. The rate of deuteration was obtained by H
1
NMR spectroscopy. D>99%. H NMR (400 MHz, C6D6) δ 1.01
(s, 12H). 13C NMR (101 MHz, C6D6) δ 83.14, 24.95. 11B NMR
(128 MHz, C6D6) δ 28.36 (s). 2H NMR (92 MHz, CH2Cl2) δ 4.03
(d, J = 30.8 Hz). HRMS-EI (m/z): Calcd for [C6H12DBO2]+:
128.1108; found: 128.1112.
4.4. General procedure for deuteroboration of alkynes with
DBpin
In a N2 filled glovebox, DBpin (0.5 mmol, 1 equiv) and 11
(0.55 mmol, 1.1 equiv) were added successively to a solution of
complex 1 (4.4 mg, 10 µmol, 2 mol%) and NaBHEt3 (20 µL, 1 M
in THF, 20 µmol, 4 mol%) in toluene (1 mL) at 25 ºC in a 10 mL
vial equipped with a magnetic stir bar. The reaction mixture was
stirred at 25 ºC for 12 h and then was quenched by exposing the
reaction mixture to air. The resulting mixture was filtered with
short silica gel column and concentrated in vacuum. Yields were
4.1. General procedure for hydrogenolysis of diboron
compounds
In a N2 filled glovebox, NaBHEt3 (5 µL, 1 M in THF, 5 µmol,
0.02 mol%) was added to a mixture of diboron compound (25
mmol) and complex 1 (1.1 mg, 2.5 µmol, 0.01 mol%) in Et2O (10
mL) at 25 ºC in a 100 mL tube equipped with a magnetic stir bar.
After the mixture was stirred for minutes, the color was changed
from colorless to purple. The reaction tube was then placed in an
autoclave. The autoclave was closed, purged three times with
hydrogen (less than the pressure needed). The reaction mixture
was stirred at 25 ºC under H2 atmosphere (15 bar) for 9 h. After
part of hydrogen was released, the autoclave was opened in a N2
filled glovebox. The reaction mixture was transferred to a 100
mL flask equipped with a magnetic stir bar. The Et2O solvent
was removed via distillation under 1 atm of argon and the desired
hydroborane was obtained by vacuum transfer as a clear,
colorless liquid into an oven-dried, 50 mL flask.
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determined by H NMR spectroscopy using mesitylene as an
internal standard. Then the residue was purified by
chromatography on silica gel eluting with ethyl acetate/n-hexane
(1:50) to give the product 12-d. The isolated yields were also
obtained. The rate of deuterium incorporation was determined by
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comparing H NMR spectroscopy with that of the corresponding
hydroboration products [14].
4.5. General procedure for one-pot synthesis of deuterated
vinylboronates
In a N2 filled glovebox, NaBHEt3 (20 µL, 1 M in THF, 20
µmol, 4 mol%) was added to a solution of B2pin2 (0.25 mmol, 0.5
equiv) and complex 1 (4.4 mg, 10 µmol, 2 mol%) in toluene (1
mL) at 25 ºC in a 10 mL tube equipped with a magnetic stir bar.
After the mixture was stirred for minutes, the color was changed
to from colorless to black. The reaction tube was then placed in
an autoclave. The autoclave was closed, purged three times with
D2 (less than the pressure needed). The reaction mixture was
stirred at 25 ºC under D2 atmosphere (5 bar) for 1 h. After release
part of gas, the autoclave was opened in a nitrogen glovebox.
Then 11 (0.55 mmol, 1.1 equiv) was added to the mixture. The
reaction mixture was stirred for another 12 h and then was
quenched by exposing the reaction mixture to air. The resulting
solution was filtered with short silica gel column and
4.2. General procedure for one-pot synthesis of alkyl boronates
In a N2 filled glovebox, NaBHEt3 (5 µL, 1 M in THF, 5 µmol,
1 mol%) was added to a mixture of B2pin2 (0.375 mmol, 0.75
equiv) and complex 1 (1.1 mg, 2.5 µmol, 0.5 mol%) in THF (1
mL) at 25 ºC in a 10 mL tube equipped with a magnetic stir bar.
After the mixture was stirred for minutes, the color was changed
from colorless to black. The reaction tube was then placed in an
autoclave. The autoclave was closed, purged three times with
hydrogen (less than the pressure needed). The reaction mixture
was stirred at 25 ºC under H2 atmosphere (5 bar) for 1 h. After
release part of hydrogen, the autoclave was opened in a nitrogen
glovebox. Then 8 (0.5 mmol, 1 equiv) was added to the mixture.
The reaction mixture was stirred for another 2 h and then was
quenched by exposing the reaction mixture to air. The resulting
solution was concentrated in vacuum and the residue was
purified by chromatography on silica gel eluting with ethyl
acetate/n-hexane (1:50) to give the product 9.
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concentrated in vacuum. Yields were determined by H NMR
spectroscopy using mesitylene as an internal standard. Then the
residue was purified by chromatography on silica gel eluting with
ethyl acetate/n-hexane (1:50) to give the product 12-d. The
isolated yields were also obtained. The rate of deuterium
incorporation was determined by comparing 1H NMR
spectroscopy with that of the corresponding hydroboration
products.
4.3. Procedure for deuterogenolysis of B2pin2