Cobalt- and Iron-Catalyzed Isomerization-Hydroboration of Branched Alkenes: Terminal Hydroboration with Pinacolborane and 1,3,2-Diazaborolanes

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1 Cobalt- and Iron-Catalyzed Isomerization-Hydroboration of Branched Alkenes: Terminal Hydroboration with Pinacolborane and 1,3,2-Diazaborolanes Takahiko Ogawa, a Adam J. Ruddy, a Orson L. Sydora, *,b Mark Stradiotto, *,a and Laura Turculet *,a a Department of Chemistry, Dalhousie University, 6274 Coburg Road, P.O , Halifax, Nova Scotia B3H 4R2, Canada b Research and Technology, Chevron Phillips Chemical LP, 1862 Kingwood Drive, Kingwood, Texas 77339, USA Supporting Information A. General Considerations (S2) B. N-Phosphinoamidine Ligand Syntheses (S2) C. Characterization of Hydroboration Products (S5) D. NMR Spectroscopic Data (S7) E. Table S1. Summary of Bond Lengths (Å) and Angles (deg.) for C1-C7 (S31) F. References (S32) S1

2 A. General Considerations. Unless stated, all manipulations were carried out under an atmosphere of purified nitrogen gas within a glovebox or by use of standard Schlenk techniques, employing dry, deoxygenated solvents; benzene and pentane were deoxygenated and dried by sparging with nitrogen and subsequent passage through a double-column solvent purification system featuring one column packed with activated alumina and one column packed with activated Q5, whereas tetrahydrofuran was dried over sodium/benzophenone and distilled under nitrogen. Procedures conducted under air made use of solvents or reagents that were used as received without further purification. In some cases fewer than expected 13 C NMR signals were observed, especially boron-c units, despite prolonged acquisition times. B. N-Phosphinoamidine Ligand Syntheses Scheme S1. Synthesis of HL tbu, HL otol, and HL Ad. Synthesis of HL otol. HL otol was prepared as outlined in Scheme S1 according to published literature procedures analogous to those employed in the synthesis of HL tbu. S1 A Schlenk flask was charged with a magnetic stir bar, N-(2,6-diisopropylphenyl)benzamidine (5.00 g, 17.8 mmol), and THF (100 ml); the flask was cooled to -78 C and magnetic stirring was initiated, followed by the dropwise addition of nbuli (11.2 ml of a 1.6 M solution in hexanes, 17.8 mmol). After addition of the nbuli was completed, the mixture was allowed to warm to room temperature under the influence of magnetic stirring, followed by the addition of (o-tol) 2 PCl (4.43 g, 17.8 mmol). The reaction mixture was then heated at 60 C for approximately 18 h, after which the reaction mixture was cooled and the volatiles were removed in vacuo. The residue was extracted by using benzene (50 ml) and was filtered through Celite. The filtrate was concentrated in vacuo and was washed with pentane (50 ml) S2

3 to yield HL otol as a white powder (6.26 g, 10.6 mmol, 72 %); this compound exists as a tautomeric mixture in some cases exhibited broadened NMR signals, as has been observed in related compounds. S2 1 H NMR (500 MHz, in C 6 D 6 ): δ 1.03 (2H), 1.15 (6H), 1.28 (4H), 2.08 (4H), 2.52 (2H), 3.26 (2H), 4.72, 5.22 (1H, NH), (13H), 7.97 (1H). 31 P{ 1 H} NMR (202 MHz, in C 6 D 6 ): δ 11.9 (minor tautomer, 29 %), 13.5 (major tautomer, 71 %). 13 C{ 1 H} NMR (125 MHz, in C 6 D 6 ) δ 20.9, 21.1, 22.8, 23.0, 24.3, 29.3, 123.6, 124.0, 124.5, 127.1, (overlapped with solvent), 129.4, 129.9, 130.4, 130.6, 131.1, 138.4, FT-IR (thin film, cm 1 ): 3312 (N-H), 1630 (C=N). HRMS (ESI): [M + H] + calcd for C 33 H 38 N 2 P , found Synthesis of HL Ad. HL Ad was synthesized using same procedure of HL otol using (1-adamantyl) 2 PCl instead of (o-tol) 2 PCl (colorless crystals, 93 % yield); this compound exists as a tautomeric mixture, as has been observed in related compounds. S2 1 H NMR (300 MHz, in C 6 D 6 ): δ (m, 44H, adamantyl and isopropyl), 3.43 (m, 2H, CH), 5.27 (d, J = 9.0 Hz, 1H, NH), 7.22 (m, 2H, Ar-H overlapped with solvent), 7.29 (m, 4H, Ar-H), 7.96 (m, 2H, Ar-H). 31 P{ 1 H} NMR (121 MHz, in C 6 D 6 ): δ 54.9 (minor tautomer, 12 %), 59.1 (major tautomer, 88 %). 13 C{ 1 H} NMR (75 MHz, in C 6 D 6 ): δ 21.9, 24.0, 28.5, 28.6, 29.3, 37.0, 38.4, 38.7, 39.3, 39.5, 123.3, 123.7, 128.8, 130.1, 137.5, 138.6, 144.6, 156.5, FT-IR (thin film, cm 1 ): 3315 (N-H), 1624 (C=N). HRMS (ESI): [M + H] + calcd for C 39 H 54 N 2 P , found Scheme S2. Synthesis of HL ArF. Synthesis of HL 35FAr. Ligand precursor N'-(2,6-diisopropylphenyl)-3,5-difluorobenzamidine (S1, Scheme S2) was synthesized by using the same procedure employed in the synthesis of N'-(2,6-diisopropylphenyl)benzamidine; S2 HL 35FAr in turn was prepared from S1 and tbu 2 PCl using the same procedure employed in the synthesis of HL otol (colorless crystals, yields 67 %). 1 H NMR S3

4 (500 MHz, in C 6 D 6 ): δ 0.78 (d, J = 12.0 Hz, 18H, tbu), 1.27 (d, J = 7.0 Hz, 6H, (CH 3 ) 2 CH-), 1.32 (d, J = 6.5 Hz, 6H, (CH 3 ) 2 CH-), 3.18 (m, 2H, (CH 3 ) 2 CH-), 5.14 (d, J = 8 Hz, 1H, NH), 6.50 (m, 1H, Ar-H), 7.90 (m, 1H, Ar-H), 7.20 (m, 2H, Ar-H), 7.54 (m, 2H, Ar-H). 31 P{ 1 H} NMR (121 MHz, in C 6 D 6 ): δ C{ 1 H} NMR (125 MHz, in C 6 D 6 ) δ 22.3, 24.8, 28.3 (J = 15.0 Hz), 29.6, 34.6 (J = 23.8 Hz), (m), (m), 124.2, 125.0, 139.3, 140.8, 144.2, (m), (m), (m). 19 F{ 1 H} NMR (471 MHz, in C 6 D 6 ): δ FT-IR (thin film, cm -1 ): 3314 (N-H), 1615 (C=N). HRMS (ESI): [M + H] + calcd for C 27 H 40 F 2 N 2 P , found Scheme S3. Synthesis of HL guan. Generation of S3 and synthesis of S4. Based on a literature procedure (Scheme S3), S3 in air a 100 ml single-neck flask was charged with a magnetic stir bar, N-(2,6-diisopropylphenyl)thiourea S2 S4 (3.2 g, 13.5 mmol), H 2 O (10 ml), sodium chloride (0.500 g, 8.56 mmol), and sodium molybdate dihydrate (0.100 g, mmol); the flask was cooled to 0 C and magnetic stirring was initiated. H 2 O 2 (10 ml) was added dropwise to the cooled suspension. After the addition was completed, the reaction mixture was stirred for 3 h. The precipitated product S3 was collected by filtration, and was then washed with acetonitrile (5 ml). A solution of piperidine (1.52 g, 17.9 mmol, 1.3 eq.) in acetonitrile (5 ml) was added slowly to a suspension of S3 (3.90 g, 13.7 mmol) in acetonitrile (20 ml) at room temperature. The reaction mixture was stirred magnetically for 18 h, after which the precipitate that had formed was removed by filtration. The reaction is worked up by adjusting the ph to the range of with 3 N NaOH. The reaction mixture was extracted with CH 2 Cl 2 (20 ml), dried over MgSO 4, and concentrated in vacuo. The desired guanidine S4 was obtained as a white solid (1.86 g, 6.47 mmol, 47 %). 1 H NMR (500 MHz, in CDCl 3 ): δ 1.22 (m, 12H, CHCH 3 ), 1.59 (m, 2H, -NCH 2 CH 2 CH 2 -), 1.77 (m, 4H, -NCH 2 CH 2 CH 2 -), 3.08 (m, 2H, CHCH 3 ), 3.16 (m, 4H, -NCH 2 CH 2 CH 2 -), 5.81 (br, NH 2 ), 7.19 (overlapped, 3H, Ar-H). 13 C{ 1 H} NMR (125 MHz, in CDCl 3 ): δ 22.6, 22.8, 24.0, 24.8, 28.2, 45.1, 124.3, 124.8, 125.6, 140.7, S4

5 Synthesis of HL guan. HL guan was prepared from S4 and tbu 2 PCl using the same procedure employed in the synthesis of HL otol (colorless crystals, 68 % yield); this compound exists as a tautomeric mixture, as has been observed in related compounds. S2 1 H NMR (300 MHz, in C 6 D 6 ): δ 0.93 (d, J = 19.0 Hz, 18H, tbu), (m, 12H, (CH 3 ) 2 CH-), 1.44 (m, 2H, CH 2 ), 1.65 (m, 4H, CH 2 ), 3.27 (m, 2H, CH), 3.46 (m, 4H, CH 2 ), 4.39 (d, J = 9.9 Hz, 1H, NH), (m, 3H, Ar-H), 7.23 (d, 2H, m-ar). 31 P{ 1 H} NMR (121 MHz, in C 6 D 6 ): δ 64.2 (s, major tautomer 97 %), 68.4 (s, minor tautomer 3 %). 13 C{ 1 H} NMR (75 MHz, in C 6 D 6 ): δ 22.1, , 26.4, 28.5 (J = 26.3 Hz), 29.3, 34.5 (J = 42.5 Hz), 51.1, 51.2, 123.7, 140.1, 145.3, FT-IR (thin film, cm 1 ) 3332 (N-H), 1616 (C=N). HRMS (ESI): [M + H] + calcd for C 26 H 47 N 3 P , found C. Characterization of Hydroboration Products. 2-(2-Methylpentyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane, 3. S5 The title compound was isolated as a colorless oil (84 %). 1 H NMR (300 MHz, in CDCl 3 ): δ 0.65 (dd, J = 8.4, 15.3 Hz, 1H), (m, 7H), 0.91 (m, 16H), 1.69 (m, 1H). 13 C{ 1 H} NMR (75 MHz, in CDCl 3 ): δ 14.3, 20.3, 22.3, 24.8, 24.8, 29.2, 42.0, (2,5-Dimethylhexyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane, 4. S6 The title compound was isolated as a colorless oil (66 %). 1 H NMR (500 MHz, in CDCl 3 ): δ 0.69 (dd, J = 8.1, 15.1 Hz, 1H), (m, 10H, overlapped), 1.18 (m, 4H), 1.27 (s, 12H), 1.51 (m, 1H), 1.68 (m, 1H). 13 C{ 1 H} NMR (125 MHz, in CDCl 3 ): δ 22.9, 23.1, 23.2, 25.2, 25.3, 28.7, 30.2, 37.1, 37.8, (Cyclohexylmethyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane, 5. S7 The title compound was isolated as a colorless oil (78 %). 1 H NMR (500 MHz, in CDCl 3 ): δ 0.72 (d, J = 7.0 Hz, 2H), (m, 2H), 1.15 (m, 1H), (m, 14H), (m, 1H), (m, 5H). 13 C{ 1 H} NMR (125 MHz, in CDCl 3 ): δ 25.3, 26.8, 27.0, 34.4, 36.7, (2-Cyclohexylethyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane, 6. S8 The title compound was isolated as a colorless oil (58 %). 1 H NMR (500 MHz, in CDCl 3 ): δ 0.78 (t, J = 8.3 Hz, 2H), 0.87 (m, 2H), (m, 18H), 1.64 (m, 5H). 13 C{ 1 H}-NMR (125 MHz, in CDCl 3 ): δ 25.3, 26.9, 27.2, 31.9, 33.6, 40.4, (2,3-Dimethylbutyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane, 7. S6 The title compound was isolated as a colorless oil (41 %). 1 H NMR (300 MHz, in CDCl 3 ): δ 0.62 (dd, J = 9.3, 15 Hz, 1H), S5

6 (m, 10H), 1.25 (s, 12H), (m, 2H). 13 C{ 1 H} NMR (75 MHz, in CDCl 3 ): δ 18.5, 18.6, 19.7, 24.7, 24.9, 34.2, H and 13 C NMR data agree with previously reported data. S6 Alcohols 9 and 10a,b. 1 H and 13 C NMR data are in agreement with data obtained from commercial samples. 2-Octyl-1,3,2-benzodiazaborolane, 12. The title product was isolated as a white solid (yield 92% from 1-octene, 1a; 95 % from trans-4-octene, 1c). 1 H NMR (300 MHz, in CDCl 3 ) δ 0.89 (t, J = 6.9 Hz, 3H, CH 3 ), 1.14 (m, 2H, CH 2 ), 1.29 (m, 10H, CH 2 ), 1.52 (m, 2H, CH 2 ), 6.23 (br, 2H, NH), 6.90 (m, 2H, Ar-H), 6.95 (m, 2H, Ar-H). 13 C{ 1 H} NMR (75 MHz, in CDCl 3 ) δ 14.2, 22.8, 26.1, 29.4, 29.7, 32.1, 32.8, 110.6, 118.8, B NMR (96 MHz, in CDCl 3 ) δ HRMS (ESI): C 14 H 22 B 1 N 2 (M-H) requires , found: (4-Methylpentyl)-1,3,2-benzodiazaborolane, 13b. The title product was isolated as a white solid (90 % from 2-methyl-1-pentene, 1d; 95 % from 2-methyl-2-pentene, 1e; 95 % from 4-methyl-1-pentene, 1j). 1 H NMR (300 MHz, in CDCl 3 ) δ 0.89 (d, J = 6.6 Hz, 6H, (CH 3 ) 2 CH-), 1.35 (m, 2H, CH 2 ), 1.27 (m, 2H, CH 2 ), (overlapped, 3H, CH and CH 2 ), 6.25 (br, 2H, NH), 6.90 (m, 2H, Ar-H), 6.96 (m, 2H, Ar-H). 13 C{ 1 H} NMR (75 MHz, in CDCl 3 ) δ 22.8, 23.9, 28.0, 42.3, 110.6, 118.8, B NMR (96 MHz, in CDCl 3 ) δ HRMS (ESI): C 12 H 18 B 1 N 2 (M-H) requires , found: (3-Methylpentyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane 14a,b. S10 The title products were isolated as a colorless oil (92 % from 2-ethyl-1-butene; ratio 14a : 14b = 2 : 1). 13 C{ 1 H} NMR (14a) δ 11.1, 18.7, 24.8, 29.0, 30.5, 36.6, 82.7; (14b) δ 11.1, 24.8, , B NMR (96 MHz, in CDCl 3 ) δ (3-Methylpentyl)-1,3,2-benzodiazaborolane, 15. The title product was isolated as a white solid (93 % from 2-ethyl-1-butene, 1k). 1 H NMR (300 MHz, in CDCl 3 ) δ 0.95 (m, 6H, CH 3 CH 2 - and CH 3 CH-), (m, 6H, CH 2 ), 1.60 (m, 1H, CH), 6.34 (br, 2H, NH), 6.90 (m, 2H, Ar-H), 7.03 (m, 2H, Ar-H). 13 C{ 1 H} NMR (75 MHz, in CDCl 3 ) δ 11.5, 18.9, 29.2, 32.7, 36.7, 110.5, 118.8, B-NMR (96 MHz, in CDCl 3 ) δ HRMS (ESI): C 12 H 18 B 1 N 2 (M-H) requires , found: S6

7 D. NMR Spectroscopic Data. Figure S1. 1 H-NMR of HL otol (500 MHz, in C 6 D 6 ) S7

8 Figure S2. 31 P{ 1 H}-NMR of HL otol (202 MHz, in C 6 D 6 ) S8

9 Figure S3. 13 C{ 1 H}-NMR of HL otol (125 MHz, in C 6 D 6 ) S9

10 Figure S4. 1 H-NMR of HL Ad (300 MHz, in C 6 D 6 ) S10

11 Figure S5. 31 P{ 1 H}-NMR of HL Ad (122 MHz, in C 6 D 6 ) S11

12 Figure S6. 13 C{ 1 H}-NMR of HL Ad (75 MHz, in C 6 D 6 ) S12

13 Figure S7. 1 H-NMR of HL 35FAr (500 MHz, in C 6 D 6 ) S13

14 Figure S8. 31 P{ 1 H}-NMR of HL 35FAr (202 MHz, in C 6 D 6 ) S14

15 Figure S9. 13 C{ 1 H}-NMR of HL 35FAr (125 MHz, in C 6 D 6 ) S15

16 Figure S F{ 1 H}-NMR of HL 35FAr (471 MHz, in C 6 D 6 ) S16

17 Figure S11. 1 H-NMR of N'-(2,6-diisopropylphenyl)piperidine-1-carboximidamide, S4 (500 MHz, in CDCl 3 ) S17

18 Figure S C{ 1 H}-NMR of N'-(2,6-diisopropylphenyl)piperidine-1-carboximidamide, S4 (125 MHz, in CDCl 3 ) S18

19 Figure S13. 1 H-NMR of HL guan (300 MHz, in C 6 D 6 ) S19

20 Figure S P{ 1 H}-NMR of HL guan (122 MHz, in C 6 D 6 ) S20

21 Figure S C{ 1 H}-NMR of HL guan (75 MHz, in C 6 D 6 ) S21

22 Figure S16. 1 H-NMR of C2 (300 MHz, in C 6 D 6 ) S22

23 Figure S17. 1 H-NMR of C3 (300 MHz, in C 6 D 6 ) S23

24 Figure S18. 1 H-NMR of C4 (300 MHz, in C 6 D 6 ) S24

25 Figure S19. 1 H-NMR of C5 (300 MHz, in C 6 D 6 ) S25

26 Figure S20. 1 H-NMR of C6 (300 MHz, in C 6 D 6 ) S26

27 Figure S21. 1 H-NMR of C7 (300 MHz, in C 6 D 6 ) S27

28 Figure S22. 1 H-NMR of 2-octyl-1,3,2-benzodiazaborolane, 12 (300 MHz, in CDCl 3 ) Figure S C{ 1 H}deptq-NMR of 2-octyl-1,3,2-benzodiazaborolane, 12 (75 MHz, in CDCl 3 ) S28

29 Figure S24. 1 H-NMR of 2-(4-methylpentyl)-1,3,2-benzodiazaborolane, 13b (300 MHz, CDCl 3 ; C 6 H 6 at 7.36 ppm) Figure S C{ 1 H}deptq-NMR of 2-(4-methylpentyl)-1,3,2-benzodiazaborolane, 13b (75 MHz, CDCl 3 ; C 6 H 6 at 128 ppm) S29

30 Figure S26. 1 H-NMR of 2-(3-methylpentyl)-1,3,2-benzodiazaborolane, 15 (300 MHz, in CDCl 3 ) Figure S C{ 1 H}deptq-NMR of 2-(3-methylpentyl)-1,3,2-benzodiazaborolane, 15 (75 MHz, in CDCl 3 ) S30

31 E. Table S1. Summary of Bond Lengths (Å) and Angles (deg.) for C1-C7 C1 S9 C2 C3 C4 C5 C6 C7 Co P (7) (7) (4) (8) (9) (7) (3) (4) Co N (18) (13) (11) (14) (13) (18) (9) (11) Co N3 (amide) (19) (13) (11) (16) (13) (19) (10) - P N (2) (14) (11) (14) (13) 1.675(2) (10) (12) N1 C (3) (19) (16) 1.354(2) (17) 1.350(3) (15) (16) N2 C (3) 1.319(2) (16) 1.317(2) (17) 1.321(3) (15) (17) P Co N (6) 82.42(4) 80.94(3) 82.37(5) 82.04(4) 81.23(5) 82.99(3) 83.56(3) P Co N3 (amide) (6) (4) (4) (5) (4) (7) (3) - N1 Co N3 (amide) (8) (6) (5) (6) (5) (8) (5) - Co P N (7) 97.47(5) 99.58(4) 97.94(6) 98.78(5) 99.15(7) (4) (4) Co N1 C (15) (10) (8) (10) (8) (15) (7) (8) N1 C1 N (2) (13) (12) (13) (11) 123.0(2) (10) (12) P1 N2 C (16) (11) (9) (11) (10) (16) (8) (9) Co C (16) Co C (13) Co C (16) Co H S31

32 F. References S1. Ruddy, A. J.; Kelly, C. M.; Crawford, S. M.; Wheaton, C. A.; Sydora, O. L.; Small, B. L.; Stradiotto, M.; Turculet, L. Organometallics 2013, 32, S2. Sydora, O. L.; Jones, T. C.; Small, B. L.; Nett, A. J.; Fischer, A. A.; Carney, M. J. ACS Catal. 2012, 2, S3. Maryanoff, C. A.; Stanzione, R. C.; Plampin, J. N.; Mills, J. E. J. Org. Chem. 1986, 51, S4. (a) Loev, B.; Bender, P. E.; Bowman, H.; Helt, A.; McLean, R.; Jen, T. J. Med. Chem. 1972, 15, (b) Walter, W.; Rueß K.-P. Liebigs Ann. Chem. 1974, S5. Lata, C. J.; Crudden, C. M. J. Am. Chem. Soc. 2010, 132, S6. Obligacion, J. V.; Chirik, P. J. J. Am. Chem. Soc. 2013, 135, S7. Li, H.; Wang, L.; Zhang, Y.; Wang, J. Angew. Chem. Int. Ed. 2012, 51, S8. Zhang, L.; Peng, D.; Leng, X.; Huang, Z. Angew. Chem. Int. Ed. 2013, 52, S9. Ruddy, A. J.; Sydora, O. L.; Small, B. L.; Stradiotto, M.; Turculet, L. Chem. Eur. J. 2014, 20, S10. Li, Q.; Liskey, C. W.; Hartwig, J. F. J. Am. Chem. Soc., 2014, 136, S32