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H. Hopfl et al.rJournal of Organometallic Chemistry 553 1998 221–239
235
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H NMR 270 MHz, CDCl3 : ds1.52–1.62 6H, br, H-6, H-7, H-8 , 2.56 1H, br, H-9 , 2.66 3H, s, H-10 , 2.93
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1H, br, H-9 , 3.16 1H, br, H-5 , 4.06–4.32 2H, br, d, H-4 , 7.15 2H, t, H-p , 7.26 4H, t, m-H , 7.75 4H, d, o-H ,
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C NMR 67.8 MHz, DMSO-d6 : Ts273 K: ds17.97, 19.15 br, C-6, C-7, C-8 , 40.06 br, C-10 , 51.64 br, C-9 ,
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61.11 br, C-5 , 64.29 br, C-4 , 126.16 p , 127.18 m , 132.72 o , Ts213 K: ds16.93 C-7 , 18.42 and 18.54
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C-6, C-8 , 40.27 C-10 , 50.78 C-9 , 60.25 C-5 , 63.82 C-4 , 125.83 p , 126.08 p , 127.24 m , 127.83 m ,
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131.30 o , 133.34 o , 147.1 br, i , 147.6 br, i , B NMR 28.9 MHz, DMSO-d6 : ds10 br ppm.
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IR KBr n cm : 3457 br, m , 3068 m , 3044 m , 2992 m , 2978 m , 2952 m , 2872 m , 1654 m , 1638
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1026 m .
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m , 1560 m , 1542 w , 1534 w , 1468 s , 1430 s , 1200 m , 1178 m , 1160 m , 1136 m , 1096 s , 1086 s ,
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MS EI, 70 eV, DIP mrz: 293 M , 1 , 292 M-H, 1 , 216 M -C6 H5, 15 , 165 4 , 98 C6 H12 N , 100 , 77
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C6 H5 , 4 , 42 C2 H4 N , 13 .
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4.2.5. Preparation of N™B -diphenyl 2- 2-piperidyl ethoxy borane 5
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0.90 g 6.97 mmol of 2-piperidineethanol were dissolved in methanol and the solution was cooled to y788C.
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Diphenylborinic acid prepared from 1.80 g 8.00 mmol of 2-aminoethyldiphenylborinate was added and the solvent
was slowly evaporated at 08C. The colourless product was washed with diethylether, filtered and dried to obtain 1.57
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g 5.35 mmol of 5. The reaction was also performed at room temperature in THF. After evaporation of the solvent
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the product was precipitated with hexane 1.56 g, 4.64 mmol .
Crystals suitable for X-ray crystallography were obtained after recrystallization in benzenerhexane.
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C19 H24 BNO MWs293.21 g mol , m.p. 169–1718C, yield 77% 67% .
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H NMR 500 MHz, DMSO-d6 : ds1.04 1H, d, H-5 , 1.38–1.60 4H, m, H-7, H-8, H-9 , 1.71 1H, m, H-9 ,
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1.88 1H, m, H-7 , 2.29 2H, m, H-5 , H-10 , 2.90 1H, dd, H-10 , 3.50 1H, d, H-6 , 3.68–3.80 2H, m, H-4 , 5.98
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1H, d, H-1 , 6.93 1H, t, p-H , 7.01 1H, t, p -H , 7.04 2H, t, m-H , 7.16 2H, t, m -H , 7.36 2H, d, o-H , 7.52 2H,
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d, o -H , JH-10 s15 Hz, JH-5 s15 Hz, C NMR 125.8 MHz, DMSO-d6 : ds17.02 C-8 , 23.15 C-9 , 25.16
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C-5 , 28.93 C-7 , 39.82 C-10 , 51.34 C-6 , 59.71 C-4 , 124.28 p , 124.51 p , 126.40 m , 126.98 m , 131.37
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o, o , 133.6 br, i ,151.2 br, i , B NMR 28.9 MHz, CDCl3 :ds1 br , B NMR 28.9 MHz, DMSO-d6 :
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ds5 br ppm.
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IR KBr n cm : 3438 br, m , 3230 m , 3066 m , 2998 s , 2944 m , 1636 s , 1560 w , 1540 w , 1508
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w , 1458 w , 1430 m , 1368 w , 1262 m , 1230 s , 1196 s , 1065 w , 1030 w , 1025 w .
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MS EI, 70 eV, DIP mrz: 293 M , 6 , 292 M -H, 11 , 216 M -C6 H5, 100 , 84 C5H10 N , 81 , 77 C6 H5 ,
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24 , 55 28 , 42 C2 H4 N , 13 .
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4.2.6. Preparation of N™B -diphenyl 3-piperidyloxy borane 6
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1.00 g 7.27 mmol of 3-hydroxypiperidine hydrochloride was dissolved in 5 ml H2O and 0.29 g 7.25 mmol of
solid NaOH were added. After addition of 25 ml benzene the solution was refluxed for 30 min, whereby the water in
the reaction solution was separated by a Dean-Stark trap. After addition of diphenylborinic acid prepared from 1.80 g
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8.00 mmol of 2-aminoethyldiphenylborinate a white precipitate of 6 formed that was separated, washed with
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diethylether and dried 0.75 g, 2.83 mmol . A higher yield could be obtained by the following method: The
3-hydroxypiperidine hydrochloride was dissolved in 5 ml of methanol and solid NaOH was added. After filtration the
solution was cooled to y788C and the diphenylborinic acid was added. Evaporation of the solvent under cooling and
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workup provided 1.10 g 4.15 mmol of 6.
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C17 H20 BNO MWs265.16 g mol , m.p. 216–2188C, yield 39% 57% .
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H NMR 270 MHz, DMSO-d6 : ds1.12 1H, dd, H-7 , 1.42 1H, m, H-8 , 1.67 1H, dd, H-8 , 1.80 1H, m,
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H-7 , 2.70–2.98 4H, m, H-5, H-6 , 4.39 1H, t, H-4 , 6.85 1H, s, H-1 , 6.98 2H, m, p-H , 7.12 4H, m, m-H , 7.51
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2H, d, o-H , 7.58 2H, d, o -H , C NMR 67.8 MHz, DMSO-d6 : ds17.17 C-7 , 30.66 C-8 , 46.81 C-6 , 53.51
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C-5 , 68.85 C-4 , 124.59 p , 126.61 m , 130.74 o , 130.90 o , 151.1 br, i , 153.6 br, i , B NMR 86.6
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MHz, DMSO-d6 : ds6 h1r2 s619 Hz ppm.
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IR KBr n cm : 3276 br, m , 3064 m , 3022 m , 2998 m , 2968 m , 2944 s , 2904 s , 1638 s , 1470 s ,
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1454 m , 1430 s , 1316 w , 1294 m , 1238 s , 1210 s , 1176 m , 1136 s , 1108 s , 1056 m , 1040 s .
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MS EI, 70 eV, DIP mrz: 265 M , 10 , 264 M -H, 12 , 188 M -C6 H5, 100 , 113 13 , 104 40 , 91 42 , 84
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C5H10 N , 67 , 77 C6 H5 , 32 , 44 C2 H6 N , 100 .
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4.2.7. Preparation of N™B -diphenyl 1-methyl-3-piperidyloxy borane 7
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0.25 g 2.22 mmol of 1-methyl-3-hydroxypiperidine were dissolved in THF and diphenylborinic acid prepared
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from 0.54 g 2.40 mmol of 2-aminoethyldiphenylborinate was added. After 4 h of reflux the solvent was slowly
evaporated. The colourless product was washed with diethylether and hexane, filtered and dried to obtain 0.40 g 1.43
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mmol of 7.