10.1002/chem.201902681
Chemistry - A European Journal
FULL PAPER
6.6 Hz, HiBuCH3, 3H), 1.37 (d, 3JHH = 6.6 Hz, HiBuCH3, 3H), 1.34 (d, 3JHH = 6.6
Hz, HiBuCH3, 3H), 1.29 (d, 3JHH = 6.5 Hz, HiBuCH3, 3H), 1.29 (d, 3JHH = 6.5 Hz,
HiBuCH3, 3H), 1.28 (d, 3JHH = 6.5 Hz, HiBuCH3, 3H), 1.14 (dd, 2JHH = 14.2 Hz,
Experimental Section
All operations were conducted under a dry argon atmosphere using
standard Schlenk and glovebox techniques. Solvents were dried rigorously
and degassed before use. Me3P=CH2,[24] iBu2BCl[25] and LiP(tBu)2[26] were
synthesized according to literature procedures. The chemical shifts are
expressed in parts per millions and 1H and 13C signals are given relative
to TMS. Coupling constants J are given in Hertz as positive values
regardless of their real individual signs. The multiplicity of the signals is
indicated as s, d, q, sept or m for singlets, doublets, quartets, septets or
multiplets, respectively. The assignments were confirmed as necessary
with the use of 2D NMR correlation experiments. Mass spectrometry
measurements were performed on an Advion expressionL CMS mass
spectrometer under atomic pressure chemical ionization (APCI). IR
spectra were measured with a Bruker Alpha spectrometer using the
attenuated total reflection (ATR) technique on powdered samples, and the
data are quoted in wavenumbers (cm–1). The intensity of the absorption
band is indicated as vw (very weak), w (weak), m (medium), s (strong), vs.
(very strong) and br (broad). Melting points were measured with a Thermo
Fischer melting point apparatus and are not corrected. Elemental analyses
were carried out in the institutional technical laboratories of the Karlsruhe
Institute of Technology (KIT).
3JHH = 7.5 Hz, HiBuCH2, 1H), 1.08 (dd, 2JHH = 13.7 Hz, 3JHH = 5.5 Hz, HiBuCH2
1H), 1.00 (d, 2JPH = 12.5 Hz, HBCPMe3, 9H), 0.92 (dd, 2JHH = 12.5 Hz, 3JHH
,
=
5.1 Hz, HiBuCH2, 1H), 0.85 (dd, 2JHH = 12.9 Hz, 3JHH = 6.1 Hz, HiBuCH2, 1H),
0.89 (d, 2JPH = 13.5 Hz, HCCPMe3, 9H), 0.63 (dd, 2JHH = 14.1 Hz, 3JHH = 3.7
Hz, HiBuCH2, 1H), 0.54 (dd, 2JHH = 14.2 Hz, 3JHH = 4.7 Hz, HiBuCH2, 1H), 0.36
2
3
2
(dd, JHH = 12.8 Hz, JHH = 5.0 Hz, HiBuCH2, 1H), 0.32 (d, JPH = 22.8 Hz,
HBC(H)P,1H), 0.31 (dd, 2JHH = 12.2 Hz, 3JHH = 5.1 Hz, HiBuCH2, 1H); 11B NMR
(96 MHz, C6D6, ppm): δ = 7.2 (bs), –9.4 (s); 13C{1H} NMR (75 MHz, C6D6,
ppm): δ = 231.9 (bs, CCO), 59.3 (d, 1JCP = 88.2 Hz, CPCC), 40.2 (bs, CiBuCH2),
29.6 (s, CiBuCH3), 29.1 (s, CiBuCH3), 29.0 (s, CiBuCH3), 28.9 (s, CiBuCH3), 28.6
(s, s, CiBuCH), 28.6 (s, CiBuCH3), 27.7 (s, CiBuCH3), 27.0 (s, CiBuCH), 27.0 (s,
1
CiBuCH), 26.9 (s, CiBuCH3), 15.4 (d, JPC = 52.1 Hz, CBCPMe), 14.6 (bs, CBCP
)
12.4 (d, 1JPC = 58.0 Hz, CCCPMe); 31P{1H} NMR (121 MHz, C6D6, ppm): δ =
22.8 (s,Pdiastereomer1_BCP), 22.7 (s, Pdiastereomer2_BCP), -4.23 (s, PCCP); APCI-
MS: decomposition; melting point: 181° C; elemental analysis:
C25H56B2OP2 calc. C 65.81; H 12.37; found. C 65.64; H 12.32; IR (ATR,
cm-1): ῦ = 2936 (m), 1893 (w), 2850 (s), 2802 (w), 1451 (m), 1437 (s), 1356
(vw), 1331 (w), 1311 (w), 1288 (m), 1242 (w), 1159 (w), 1132 (w), 1107
(m), 1077 (m), 970 (s), 944 (vs), 907 (s), 861 (s), 823 (m), 748 (vs), 718
(s), 691(vs),648 (m), 620 (m), 602 (m), 574 (m), 546 (s), 525 (vs), 497 (s),
485 (s), 469 (m), 459 (m), 449 (m), 440 (m), 430 (s), 421 (s), 410 (m), 401
(m), 392 (m), 382 (m).
Synthesis of 1. To a solution of iBu2BCl (7.67 g, 47.8 mmol) in 200 ml
pentane was slowly added a suspension of LiP(tBu)2 (7.61 g, 50.0 mmol)
in 200 ml pentane at –50 °C. After stirring the suspension at –40 °C for 48
hours the suspension was filtered in the cold and washed with cold
pentane. The residue was extracted with cold toluene. At –50 °C to this
solution was added a solution of Me3P=CH2 (1.85 g, 20.5 mmol) in 50 ml
pentane. White precipitate formed. After cold filtration the precipitate was
washed with cold pentane. (From this precipitate, the NMR spectra of
Me2P(CH2)2B(iBu)2 were measured.) At room temperature, the solid turned
4: A solution of 700 mg (3.27 mmol) of 1 in 10 ml toluene was degassed
with two freeze-pump-thaw cycles and subsequently purged with 1.1 bar
CO2. The solution was stirred and heated to 90 °C overnight. The solvent
and all volatile compounds were evaporated in high vacuum. After
removing all volatiles, the crude product was only slightly soluble in toluene.
Crude 4 was recrystallized in toluene, yielding after removal of the
supernatant layer and drying in high vacuum 538 mg (0.657 mmol, 60 %)
colourless crystalline 4. Crystals suitable for X-ray diffraction were
obtained by solving a small amount of 4 in hot toluene and cooling the
solution very slowly to room temperature: 1H NMR (300 MHz, THF-d8,
liquid. Distillation at high vacuum (p = 3 · 10-6 bar) at 20 °C yields 1 (2.01
g, 9.39 mmol, 52%): 1H NMR (300 MHz, C6D6, ppm): δ = 2.36 (d, JPH
=
2
3
12.1 Hz, Hylid, 1H), 2.26 (nonet, JHH = 6.7 Hz, HiBuCH, 2H), 2.21 (nonet,
3JHH = 6.7 Hz, HiBuCH, 2H), 1.28 (d, 3JHH = 6.8 Hz, HiBuCH2, 2H), 1.27 (d, 3JHH
2
2
ppm): δ = 2.03 (d, JPH = 15.2 Hz, HPMe3, 12H), 1.80 (d, JPH = 14.1 Hz,
= 6.5 Hz, HiBuCH3, 6H), 1.16 (d, 3JHH = 6.5 Hz, HiBuCH3, 6H), 1.12 (d, 3JHH
=
=
3
HPMe4, 18H), 1.76 – 1.65 (m, HiBuCH_ring, 4H) ,1.59 (sept, JHH = 6.5 Hz,
3
2
7.2 Hz, HiBuCH2, 1H), 1.12 (d, JHH = 7.2 Hz, HiBuCH2, 1H), 0.86 (d, JPH
HiBuCH_bridge, 2H), 0.86 (d, J = 6.5 Hz, HiBuCH3_ring, 24H), 0.84 (d, J = 6.5 Hz,
HiBuCH3_bridge, 12H), 0.66 (d, J = 6.9 Hz, HiBuCH2_bridge, 4H) 0.28 (bs,
HiBuCH2_ring, 8H). 11B NMR (96 MHz, THF-d8, ppm): δ = –14.9 (bs); 13C{1H}-
NMR (101 MHz, THF-d8, ppm): δ = 174.0 (bs, CCO2), 171.8 (bs, CCO2), 57.5
(d, 1JPC = 128 Hz, CPCCO) 35.2 (bs, CiBuCH2_ring), 32.6 (bs, CiBuCH2_bridge), 27.9
(s, CiBuCH3_ring), 27.0 (s, CiBuCH3_bridge), 27.0 (s, CiBuCH_bridge), 26.5 (s,
CiBuCH_ring), 13.9 (d, JPC = 62.0 Hz, CPMe3), 9.9 (d, JPC = 44.8 Hz, CPMe4);
31P{1H} NMR (121 MHz, THF-d8, ppm): δ = 25.7 (s, PMe4), 9.9 (s, Pylid);
APCI-MS: decomposition; melting point: 174 °C (decomp.); elemental
analysis (%): C40H84B3O8P3 calc. C, 58.70, H, 10.35 found C, 58.34, H,
10.73; IR (ATR, cm-1): ῦ = 2983 (vw), 2937 (w), 2854 (w), 2792 (vw), 1592
(m), 1579 (m), 1490 (vs), 1452 (vs), 1407 (m), 1373 (vw), 1356 (vw), 1318
(m), 1291 (w), 1245 (m), 1179 (w), 1100 (m), 1058 (w), 982 (s), 964 (s),
947 (s), 898 (w), 865 (w), 840 (m), 816 (w), 789 (m), 756 (m), 729 (vw),
681 (m), 629 (vw), 585 (w), 534 (vw), 506 (vw), 464 (w), 419 (vw), 404 (vw).
12.6 Hz, HPMe3, 9H); 11B-NMR (96 MHz, C6D6, ppm): δ = 54.7 (s); 13C{1H}
NMR (75 MHz, C6D6, ppm): δ = 48.5 (bs, Cylid), 37.2 (bs, CiBuCH2), 36.0 (bs,
CiBuCH2), 27.3 (s, CiBuCH1), 27.3 (s, CiBuCH1), 26.7 (s, CiBuCH3), 26.7 (s,
1
CiBuCH2), 17.6 (d, JPC = 56.2 Hz, CPMe3); 31P{1H} NMR (121 MHz, C6D6,
ppm): δ = 2.03 (s); EI-MS: 214.20214, C12H2811BP, calc. 214.20216;
elemental analysis (%): C12H28BP calc. P, 14.46, B, 5.05 found P, 14.40,
B, 5.08; cryoscopy (benzene, g mol–1): calc. 214.14, found 212.0; IR (ATR,
cm-1): ῦ = 2944 (m), 2891 (w), 2860 (m), 1461 (w), 1419 (w), 1375 (m),
1347 (vs), 1315 (s), 1289 (m), 1250 (w), 1207 (vw), 1155 (w), 1091 (vw),
1056 (vw), 1034 (vw), 980 (s), 936 (s), 890 (w), 858 (w), 816 (w), 750 (w),
731 (m), 697 (w), 647 (vw), 577 (vw), 500 (vw), 412 (vw).
1
1
Synthesis of 3: A Schlenk tube with a solution of 0.864 g (1.00 ml, 4.03
mmol) 1 in 10 ml toluene was degassed with two freeze-pump-thaw cycles
and subsequently purged with CO. The reaction mixture was stirred and
heated to 70 °C for three hours. The solution was evaporated to dryness.
Pentane (20 ml) was added to the residue, yielding a thin suspension. The
suspension was filtered. The filtrate was reduced until crude 3 precipitates.
Recrystallisation in boiling pentane, taking of the supernatant layer and
drying in high vacuum yielded 250 mg (0.548 mmol, 14 %) pure 3 (both
diastereomers) as colourless crystals. Suitable crystals for X-ray diffraction
were obtained by solving 3 in a small amount of boiling hexane and cooling
5: A solution of 500 mg 1 in 8 ml hexane and a solution of 258 mg (2.16
mmol) PhNCO in 8 ml hexane were combined under stirring at room
temperature. Stirring was discontinued and crude 5 crystallised. After one
hour reaction time, the supernatant layer was taken off and the colourless
crystals were dried in high vacuum. The crude product was solved in
benzene and filtered. Evaporation of the solvent and drying in high vacuum
yielded 282 mg (0.846 mg, 39 %) pure 5. Crystals suitable for X-ray
diffraction were obtained by slow solvent evaporation of a benzene
the solution very slowly to room temperature: 1H NMR (signal assignment
2
where necessary with 1H{11B}) (300 MHz, C6D6, ppm): δ = 3.54 (d, JPH
=
,
solution of 5: 1H NMR (300 MHz, C6D6, ppm): δ = 7.28 – 7.26 (m, Hortho/meta
,
2
32.1 Hz, Hdiastereomer1_C=C, 0.5H), 3.53 (d, JPH = 32.1 Hz, Hdiastereomer2_C=C
2
4H), 6.92 – 6.83 (m, Hpara, 1H), 2.62 (d, JPH = 18.2 Hz, Hylide, 1H), 2.15
0.5H), 2.35-2.17 (m, HiBuCH1, 2H), 2.04-1.82 (m, HiBuCH1, 2H), 1.46 (d, 3JHH
= 6.5 Hz, HiBuCH3, 3H) , 1.43 (d, 3JHH = 6.6 Hz, HiBuCH3, 3H), 1.37 (d, 3JHH
(sept, 3JHH = 6.6 Hz, HiBuCH, 2H), 1.29 (d, 3JHH = 6.6 Hz, HiBuCH3, 12H), 1.16
=
(d, JHH = 6.6 Hz, HiBuCH2, 4H), 0.75 (d, JPH = 13.6 Hz, 9H); 11B NMR (96
3
2
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