Performance of SCS palladium pincer complexes in borylation of allylic alcohols. Control of the regioselectivity in the one-pot borylation-allylation process

Article abstract of DOI:10.1021/jo9008673

(Chemical Equation Presented) One-pot borylation-allylation reactions of aldehydes and allylic alcohols were performed under various reaction conditions. The borylation of allylic alcohols was performed using a very efficient SCS palladium pincer-complex catalyst. The regioselectivity of the allylation depends on the applied solvent. The reaction in CHCl₃ gave the linear allylic product; however, when MeOH was added to the reaction mixture, the branched allylic product was formed.

Full text of DOI:10.1021/jo9008673

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Supporting Information
Performance of SCS Palladium Pincer-Complexes in Borylation of Allylic Alcohols.
Control of the Regioselectivity in the One-Pot Borylation-Allylation Process
Nicklas Selander and Kálmán J. Szabó*
Stockholm University, Arrhenius Laboratory, Department of Organic Chemistry
SE-106 91 Stockholm, Sweden. E-mail: kalman@organ.su.se. Fax: +46-8-15 49 08
Contents:
1. General Information
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2. Experimental Procedures and Spectral Data for 2a-c, 3a-e, 8a-c and 9a-c S2-S9
3. References
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4. 1H, 13C, 11B and 19F NMR spectra of 2a-c, 3a-e, 8a-c and 9a-c
S11-S47

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1. General Information
All reactions were performed in freshly distilled solvents under ambient atmosphere.
The palladium pincer-complex 1, was prepared according to literature procedure.1
All other chemicals were obtained from commercial sources and used as received.
1H NMR, 13C NMR, 11B NMR, and 19F NMR spectra were recorded in CDCl3
1
(internal standard: 7.26 ppm, H; 77.00 ppm, 13C), acetone-d6 (internal standard:
1
1
2.05 ppm, H; 29.84 ppm, 13C) or methanol-d4 (internal standard: 3.31 ppm, H;
13
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49.00 ppm, C) using Bruker 400 and 500 MHz spectrometers. B NMR chemical
shifts were referenced to external bis(pinacolato)diboron (30.70 ppm). 19F NMR
chemical shifts were referenced to external α,α,α-trifluorotoluene (-63.73 ppm). Due
to quadrupolar relaxation, the carbon atoms attached to boron atoms were not
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detected in C NMR. High resolution mass data (HRMS) were obtained using ESI
technique. For column chromatography, Merck silica gel 60 (230-400 mesh) was
used.
2. Experimental Procedures and Spectral Data
General Procedure A: Allylation of Aldehydes (Table 1). The corresponding
allylic alcohol 4 (0.15 mmol) was dissolved in chloroform (0.4 mL) or a mixture of
methanol and chloroform (0.2 mL/0.2 mL) (see Table 1), followed by addition of
bis(pinacolato)diboron (6) (0.18 mmol), pincer complex 1 (0.0075 mmol, 5 mol %),
p-toluenesulfonic acid (7) (0.0075 mmol, 5 mol %) and aldehyde 5 (0.18 mmol).
Then, this reaction mixture was stirred at 50 oC for the allotted times listed in Table
1. After evaporation of the solvent, the products 2a-c and 3a-e were purified by
silica gel chromatography.

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OH
Ph
1,2-Diphenyl-3-buten-1-ol (2a). Prepared in a mixture of methanol
and chloroform (0.2 mL/0.2 mL) according to General Procedure A.
Ph
Product 2a was isolated in 72% yield (24.2 mg) using CH2Cl2 as eluent for silica gel
chromatography. The NMR data obtained for 2a are in agreement with previously
reported literature values.2 1H NMR (400 MHz, CDCl3): δ 7.24-7.12 (m, 8H), 7.09-
7.04 (m, 2H), 6.26 (ddd, J = 8.3, 10.3, 17.1 Hz, 1H), 5.28 (d, J = 10.3 Hz, 1H), 5.23
(d, J = 17.1 Hz, 1H), 4.86 (dd, J = 2.2, 8.3 Hz, 1H), 3.56 (t, J = 8.3 Hz, 1H), 2.32 (d,
J = 2.2 Hz, 1H); 13C NMR (101 MHz, CDCl3): δ 141.8, 140.6, 137.8, 128.33,
128.30, 127.9, 127.4, 126.64, 126.58, 118.4, 77.2, 59.2; HRMS (pos. ESI) m/z:
calcd for C16H16NaO [M+Na]+ 247.1093, found 247.1097.
OH
1-(4-Nitrophenyl)-2-phenyl-3-buten-1-ol (2b). Prepared in
chloroform (0.4 mL) according to General Procedure A.
Ph
NO2
Product 2b was isolated in 74% yield (29.9 mg) using
CH2Cl2 as eluent for silica gel chromatography. The NMR data obtained for 2b are
in agreement with previously reported literature values.3 1H NMR (400 MHz,
CDCl3): δ 8.07-8.03 (m, 2H), 7.30-7.18 (m, 5H), 7.06-7.02 (m, 2H), 6.23 (ddd,
J = 9.1, 10.1, 17.1 Hz, 1H), 5.32 (d, J = 10.1 Hz, 1H), 5.27 (d, J = 17.1 Hz, 1H), 4.93
13
(d, J = 7.8 Hz, 1H), 3.47 (t, J = 8.5 Hz, 1H), 2.49 (br s, 1H); C NMR (101 MHz,
CDCl3): δ 149.1, 147.2, 139.5, 136.8, 128.7, 128.1, 127.4, 127.2, 123.1, 119.5, 76.4,
59.5; HRMS (pos. ESI) m/z: calcd for C16H15NNaO3 [M+Na]+ 292.0944, found
292.0941.
OH
3-Phenyl-1-nonen-4-ol (2c). Prepared in a mixture of methanol
C5H11
and chloroform (0.2 mL/0.2 mL) according to General Procedure
Ph

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A, except that 0.30 mmol of aldehyde 5c was used. Product 2c was isolated in 78%
yield (26.0 mg) using pentane/diethyl ether (5:1 ratio) as eluent for silica gel
chromatography. The NMR data obtained for 2c are in agreement with previously
reported literature values.2 1H NMR (400 MHz, CDCl3): δ 7.35-7.29 (m, 2H), 7.25-
7.18 (m, 3H), 6.13 (ddd, J = 9.0, 10.3, 17.0 Hz, 1H), 5.23 (d, J = 10.3 Hz, 1H), 5.20
(d, J = 17.0 Hz, 1H), 3.79 (dt, J = 3.8, 7.4 Hz, 1H), 3.25 (dd, J = 7.4, 9.0 Hz, 1H),
13
1.71 (br s, 1H), 1.52-1.14 (m, 8H), 0.85 (t, J = 7.0 Hz, 3H); C NMR (101 MHz,
CDCl3): δ 141.7, 138.4, 128.7, 128.0, 126.6, 117.8, 74.0, 57.4, 34.4, 31.8, 25.4, 22.6,
14.0; HRMS (pos. ESI) m/z: calcd for C15H22NaO [M+Na]+ 241.1563, found
241.1558.
OH
(3E)-1,4-Diphenyl-3-buten-1-ol (3a). Prepared in chloroform
Ph
Ph
(0.4 mL) according to General Procedure A. Product 3a was
isolated in 73% yield (24.6 mg) using CH2Cl2 as eluent for silica gel
chromatography. The NMR data obtained for 3a are in agreement with previously
reported literature values.4 1H NMR (400 MHz, CDCl3): δ 7.42-7.20 (m, 10H), 6.51
(d, J = 15.8 Hz, 1H), 6.22 (td, J = 7.4, 15.8 Hz, 1H), 4.82 (br t, J = 6.3 Hz, 1H),
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2.71-2.64 (m, 2H), 2.12 (br s 1H); C NMR (101 MHz, CDCl3): δ 143.9, 137.2,
133.4, 128.50, 128.45, 127.6, 127.3, 126.1, 125.9, 125.8, 73.7, 43.1; HRMS (pos.
ESI) m/z: calcd for C16H16NaO [M+Na]+ 247.1093, found 247.1085.
OH
(1E)-1-Phenyl-1-nonen-4-ol (3b). Prepared in chloroform
Ph
C5H11
(0.4 mL) according to General Procedure A. Product 3b was
isolated in 60% yield (19.7 mg) using CH2Cl2 as eluent for silica gel
chromatography. The NMR data obtained for 3b are in agreement with previously

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reported literature values.5 1H NMR (400 MHz, CDCl3): δ 7.39-7.19 (m, 5H), 6.49
(d, J = 15.8 Hz, 1H), 6.24 (ddd, J = 7.0, 7.7, 15.8 Hz, 1H), 3.77-3.69 (m, 1H), 2.50-
2.25 (m, 2H), 1.60 (br s, 1H), 1.56-1.23 (m, 8H), 0.90 (t, J = 6.5 Hz, 3H); 13C NMR
(101 MHz, CDCl3): δ 137.3, 133.1, 128.5, 127.2, 126.4, 126.1, 71.2, 41.2, 36.9,
31.9, 25.4, 22.6, 14.0; HRMS (pos. ESI) m/z: calcd for C15H22NaO [M+Na]+
241.1563, found 241.1564.
OH
(3E)-1-Phenyl-3-nonen-1-ol (3c). Prepared in chloroform (0.4
C5H11
Ph
mL) according to General Procedure A. Product 3c was
isolated in 74% yield (24.1 mg) using CH2Cl2 as eluent for silica gel
chromatography. The NMR data obtained for 3c are in agreement with previously
reported literature values.6 1H NMR (400 MHz, CDCl3): δ 7.37-7.24 (m, 5H), 5.58
(td, J = 6.7, 15.2 Hz, 1H), 5.44-5.35 (m, 1H), 4.70-4.66 (m, 1H), 2.51-2.35 (m, 2H),
2.04 (br s, 1H), 2.01 (q, J = 7.1 Hz, 2H), 1.40-1.20 (m, 6H), 0.88 (t, J = 6.8 Hz, 3H);
13C NMR (101 MHz, CDCl3): δ 144.0, 135.3, 128.3, 127.4, 125.8, 125.3, 73.4, 42.9,
32.6, 31.3, 29.1, 22.5, 14.0; HRMS (pos. ESI) m/z: calcd for C15H22NaO [M+Na]+
241.1563, found 241.1560.
OH
(E)-8-Tetradecen-6-ol (3d). Prepared in chloroform (0.4
C5H11
C5H11
mL) according to General Procedure A, except that 0.45
mmol of aldehyde 5c and 10 mol % p-toluenesulfonic acid (7) was used. Product 3d
was isolated in 72% yield (23.0 mg) using CH2Cl2 as eluent for silica gel
1
chromatography. H NMR (400 MHz, CDCl3): δ 5.54 (td, J = 6.7, 15.2 Hz, 1H),
5.45-5.36 (m, 1H), 3.61-3.54 (m, 1H), 2.27-2.20 (m, 1H), 2.10-1.98 (m, 3H), 1.57
(br s, 1H), 1.48-1.23 (m, 14H), 0.89 (t, J = 6.9 Hz, 3H), 0.88 (t, J = 6.9 Hz, 3H);

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13C NMR (101 MHz, CDCl3): δ 134.8, 125.8, 70.9, 40.7, 36.7, 32.6, 31.9, 31.4,
29.2, 25.4, 22.6, 22.5, 14.0; HRMS (pos. ESI) m/z: calcd for C14H28NaO [M+Na]+
235.2032, found 235.2035.
OH
(3E)-1-Phenyl-3,6-heptadien-1-ol
(3e).
Prepared
in
Ph
chloroform (0.4 mL) according to General Procedure A.
Product 3e was isolated in 63% yield (17.7 mg) using CH2Cl2 as eluent for silica gel
chromatography. The NMR data obtained for 3e are in agreement with previously
reported literature values.7 1H NMR (400 MHz, CDCl3): δ 7.37-7.25 (m, 5H), 5.81
(tdd, J = 6.4, 10.2, 16.8 Hz, 1H), 5.64-5.42 (m, 2H), 5.04-4.97 (m, 2H), 4.70 (dd,
J = 5.0, 7.8 Hz, 1H), 2.78 (t, J = 6.4 Hz, 2H), 2.54-2.40 (m, 2H), 1.96 (br s, 1H);
13C NMR (101 MHz, CDCl3): δ 144.0, 136.7, 132.2, 128.4, 127.5, 126.9, 125.8,
115.2, 73.5, 42.7, 36.7; HRMS (pos. ESI) m/z: calcd for C13H16NaO [M+Na]+
211.1093, found 211.1094.
General Procedure B: Preparation of Pinacolboronates 8a-c and Potassium
Trifluoroborates 9a-c (Table 2). The corresponding allylic alcohol 4 (1.00 mmol)
was dissolved in chloroform (2.0 mL) followed by addition of
bis(pinacolato)diboron (6) (1.20 mmol) and pincer complex 1 (0.05 mmol, 5 mol %).
o
This reaction mixture was then stirred at 50 C for the allotted times listed in Table
2. Thereafter, 2.0 mL of pentane was added followed by flash chromatography using
pentane/diethyl ether (95:5 ratio) as eluent to yield analytically pure allylboronates
8a-c. Potassium Trifluoroborates from Pinacolboronates. To the purified
allylboronates, 6.0 equiv of KHF2 in water/methanol (2.0 mL/2.0 mL) was added
and this mixture was stirred at room temperature for 2 h. Thereafter, the precipitate

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was separated and the filtrate containing the crude potassium trifluoroborates was
evaporated. The remaining solid was extracted with acetone and filtered through
cotton. Subsequently, the solvent was evaporated and the potassium trifluoroborates
9a-c were recrystallized from acetone/diethyl ether.
(E)-2-(3-Phenyl-2-propenyl)-4,4,5,5-tetramethyl-1,3,2-
Ph
Bpin
dioxaborolane (8a). Prepared according to General Procedure B. Compound 8a was
isolated in 79% yield (192.0 mg) using pentane/diethyl ether (95:5 ratio) as eluent
for silica gel chromatography. The NMR data obtained for 8a are in agreement with
previously reported literature values.8 1H NMR (400 MHz, CDCl3): δ 7.35-7.14 (m,
5H), 6.37 (d, J = 15.8 Hz, 1H), 6.29 (td, J = 7.1, 15.8 Hz, 1H), 1.88 (d, J = 7.1 Hz,
2H), 1.26 (s, 12H); 13C NMR (101 MHz, CDCl3): δ 138.2, 130.2, 128.3, 126.5,
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126.3, 125.8, 83.4, 24.8; B NMR (128 MHz, CDCl3): δ 32.9; HRMS (pos. ESI)
m/z: calcd for C15H21BNaO2 [M+Na]+ 267.1530, found 267.1527.
(E)-2-(2-Octenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane
C5H11
Bpin
(8b). Prepared according to General Procedure B. Compound 8b was isolated in
73% yield (174.3 mg) using pentane/diethyl ether (95:5 ratio) as eluent for silica gel
1
chromatography. H NMR (500 MHz, CDCl3): δ 5.46-5.33 (m, 2H), 1.98-1.92 (m,
2H), 1.62 (d, J = 6.4 Hz, 2H), 1.34-1.20 (m, 6H), 1.24 (s, 12H), 0.86 (t, J = 6.8 Hz,
3H); 13C NMR (126 MHz, CDCl3): δ 131.0, 124.6, 83.1, 32.7, 31.3, 29.3, 24.7, 22.5,
14.1; 11B NMR (161 MHz, CDCl3): δ 33.0; HRMS (pos. ESI) m/z: calcd for
C14H27BNaO2 [M+Na]+ 261.1999, found 261.1991.

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(E)-2-(2-Butenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (8c).
Bpin
Prepared according to General Procedure B. Compound 8c was isolated in 73% yield
(132.6 mg) using pentane/diethyl ether (95:5 ratio) as eluent for silica gel
chromatography. The NMR data obtained for 8c are in agreement with previously
reported literature values.9 1H NMR (400 MHz, CDCl3): δ 5.49-5.33 (m, 2H), 1.63-
1.60 (m, 5H), 1.23 (s, 12H); 13C NMR (101 MHz, CDCl3): δ 125.8, 125.3, 83.1,
11
24.7, 18.0; B NMR (128 MHz, CDCl3): δ 33.1; HRMS (pos. ESI) m/z: calcd for
C10H19BNaO2 [M+Na]+ 205.1372, found 205.1370.
Potassium (E)-Trifluoro(3-phenyl-2-propenyl)borate (9a).
Ph
BF3K
Prepared according to General Procedure B. Compound 9a was isolated in 77%
yield (171.9 mg) calculated from allylic alcohol 4a. The NMR data obtained for 9a
are in agreement with previously reported literature values.10 1H NMR (400 MHz,
acetone-d6): δ 7.26 (d, J = 7.9 Hz, 2H), 7.19 (t, J = 7.9 Hz, 2H), 7.02 (t, J = 7.9 Hz,
1H), 6.51 (td, J = 7.8 Hz, 15.8 Hz, 1H), 6.08 (d, J = 15.8 Hz, 1H), 1.25 (br s, 2H);
13C NMR (101 MHz, acetone-d6): δ 140.8, 136.4, 129.0, 126.4, 126.0, 125.9;
11B NMR (128 MHz, acetone-d6): δ 4.5; 19F NMR (377 MHz, acetone-d6): δ -139.9;
HRMS (neg. ESI) m/z: calcd for C9H9BF3 [M-K]- 185.0757, found 185.0754.
Potassium (E)-Trifluoro(2-octenyl)borate (9b). Prepared
C5H11
BF3K
according to General Procedure B. Compound 9b was isolated in 72% yield (158.0
mg) calculated from allylic alcohol 4b. The NMR data obtained for 9b are in
agreement with previously reported literature values.10 1H NMR (500 MHz,
methanol-d4): δ 5.51 (td, J = 7.6 Hz, 15.0 Hz, 1H), 5.14 (td, J = 6.7, 15.0 Hz, 1H),
1.92 (q, J = 6.7 Hz, 2H), 1.36-1.23 (m, 6H), 1.05 (br s, 2H), 0.89 (t, J = 6.7 Hz, 3H);

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13C NMR (126 MHz, methanol-d4): δ 133.0, 127.3, 34.2, 32.7, 31.1, 23.7, 14.4;
11B NMR (161 MHz, methanol-d4): δ 4.9; 19F NMR (377 MHz, methanol-d4):
δ -142.5; HRMS (neg. ESI) m/z: calcd for C8H15BF3 [M-K]- 179.1226, found
179.1220.
Potassium (E)-Trifluoro(2-butenyl)borate (9c). Prepared
BF3K
according to General Procedure B. Compound 9c was isolated in 60% yield (96.4
mg) calculated from allylic alcohol 4d. The NMR data obtained for 9c are in
agreement with previously reported literature values.11 1H NMR (400 MHz,
acetone-d6): δ 5.58-5.49 (m, 1H), 5.11-5.01 (m, 1H), 1.53 (qd, J = 1.4, 6.4 Hz, 3H),
13
11
1.00 (br s, 2H); C NMR (101 MHz, acetone-d6): δ 135.2, 119.7, 18.4; B NMR
19
(128 MHz, acetone-d6): δ 4.7; F NMR (377 MHz, acetone-d6): δ -140.6; HRMS
(neg. ESI) m/z: calcd for C4H7BF3 [M-K]- 123.0599, found 123.0601.
Monitoring the One-pot Transformation of Cinnamyl Alcohol (4a) by 1H NMR
Spectroscopy (Figure 1). In an NMR tube, cinnamyl alcohol 4a (0.15 mmol) was
dissolved in CDCl3 (0.4 mL) followed by addition of bis(pinacolato)diboron 6 (0.18
mmol), p-toluenesulfonic acid (7) (5 mol %), aldehyde 5a (0.18 mmol) and
palladium catalyst 1 (5 mol%). The reaction was conducted in the NMR tube at 50
°C for 12 h. The progress of the reaction was monitored using 1H NMR spectroscopy
(400 MHz), by measuring the integrals for the corresponding peaks of 2a, 3a, 4a, 5a
and 8a. Due to different relaxation times and partial overlap of certain peaks, the
estimated error of this measuring method is about 10-15 %.

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3. References:
(1) Aydin, J.; Kumar, K. S.; Eriksson, L.; Szabó, K. J. Adv. Synth. Catal. 2007, 349,
2585.
(2) Selander, N.; Kipke, A.; Sebelius, S.; Szabó, K. J. J. Am. Chem. Soc. 2007, 129,
13723.
(3) Wallner, O. A.; Szabó, K. J. J. Org. Chem. 2003, 68, 2934.
(4) Sumida, S.; Ohga, M.; Mitani, J.; Nokami, J. J. Am. Chem. Soc. 2000, 122, 1310.
(5) Loh, T.-P.; Tan, K.-T.; Hu, Q.-Y. Angew. Chem. Int. Ed. 2001, 40, 2921.
(6) Katritzky, A. R.; Wu, H.; Xie, L. J. Org. Chem. 1996, 61, 4035.
(7) Braddock, D. C.; Badine, D. M.; Gottschalk, T.; Matsuno, A.; Rodriguez-Lenz,
M. Synlett 2003, 345.
(8) Dutheuil, G.; Selander, N.; Szabó, K. J.; Aggarwal, V. K. Synthesis 2008, 2293.
(9) Keck, G. E.; Giles, R. L.; Cee, V. J.; Wager, C. A.; Yu, T.; Kraft, M. B. J. Org.
Chem. 2008, 73, 9675.
(10) Olsson, V. J.; Sebelius, S.; Selander, N.; Szabó, K. J. J. Am. Chem. Soc. 2006,
128, 4588.
(11) Batey, R. A.; Thadani, A. N.; Smil, D. V.; Lough, A. J. Synthesis 2000, 990.

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4. NMR spectra

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