Mild and Simple Preparation of Ketophosphine-boranes through Uncatalysed Hydrophosphination of Enones

Abstract

An efficient and simple method for the synthesis of γ-ketophosphines is reported. This method is based on the atom efficient hydrophosphination reaction using secondary phosphine-boranes as precursors. Different examples with various substrates and phosphine precursors are described. The reaction occurs without any ­catalyst upon simple thermal activation (50-80 °C). Reduction of a γ-ketophosphine yields in good yield and with an excellent dia­stereoselectivity a new hydroxyphosphine.

enones - phosphorus - boron - γ-ketophosphines - hydrophosphination

References

See for example:

1a Braunstein P. Naud F. Angew. Chem. Int. Ed.  2001,  40:  680 

1b Slone CS. Mirkin CS. Yap GPA. Guzei IA. Rheingold AL. J. Am. Chem. Soc.  1997,  119:  10743 

2a Johansson MH. Andersson C. Oskarsson Å. J. Mol. Struct.  2002,  606:  51 

2b Demerseman B. Eur. J. Inorg. Chem.  2001,  2347 

2c Andrews CD. Burrows AD. Lynam JM. Mahon MF. Palmer MT. New J. Chem.  2001,  25:  824 

2d Andrieu J. Braunstein P. Naud F. Adams RD. J. Organomet. Chem.  2000,  601:  43 

2e Braunstein P. Chauvin Y. Nähring J. DeCian A. Fischer J. Tiripicchio A. Ugozolli F. Organometallics  1996,  15:  5551 

2f Rasley BT. Rapta M. Kulawiec RJ. Organometallics  1996,  15:  2852 

3 Gilheany DG. Mitchell CM. The Chemistry of Organophosphorus Compounds   Vol. 1:  Hartley FR. J. Wiley and Sons Ltd; New-York: 1990.  p.151-190  

4 Issleib K. Jasche K. Chem. Ber.  1967,  100:  3343 

5a Kashman Y. Ronen H. Tetrahedron  1973,  29:  4275 

5b Kashman Y. Benary E. Tetrahedron  1972,  28:  4091 

5c Kashman Y. Awerbouch O. Tetrahedron  1970,  26:  4213 

6 Imamoto T. Oshiki T. Onozawa T. Kusumoto T. Sato K. J. Am. Chem. Soc.  1990,  112:  5244 

7 Zabotina EY. de Kanter FJJ. Bickelhaupt F. Wife RL. Tetrahedron  2001,  57:  10177 

8 Hashimoto T. Maeta H. Matsumoto T. Morooka M. Ohba S. Suzuki K. Synlett  1992,  340 

9 Gaumont A.-C. Carboni B. Science of Synthesis (Houben-Weyl)   Vol 6:  Kaufmann DE. Matesson DS. Georg Thieme Verlag; Stuttgart, New York: 2005.  p.485-512  

10a Mimeau D. Delacroix O. Join B. Gaumont A.-C. C. R. Chimie  2004,  7:  845 

10b Mimeau D. Delacroix O. Gaumont A.-C. Chem. Commun.  2003,  2928 

10c Mimeau D. Gaumont A.-C. J. Org. Chem.  2003,  68:  7016 

11a Pican S. Gaumont A.-C. Chem. Commun.  2005,  2393 

11b Denis J.-M. Forintos H. Szelke H. Toupet L. Pham TN. Madec P.-J. Gaumont A.-C. Chem. Commun.  2003,  54 

11c Gaumont A.-C. Hursthouse MB. Coles SJ. Brown JM. Chem. Commun.  1999,  63 

12a McKinstry L. Livinghouse T. Tetrahedron Lett.  1995,  36:  9319 

12b Brisset H. Gourdel Y. Pellon P. Le Corre M. Tetrahedron Lett.  1993,  34:  4523 

13 Bourumeau K. Gaumont A.-C. Denis J.-M. J. Organomet. Chem.  1997,  529:  205 

14

All compounds gave satisfactory NMR spectra and HRMS analyses. Solid compounds were also characterised by elemental analysis.

15 Bourumeau K. Gaumont A.-C. Denis J.-M. Tetrahedron Lett.  1997,  38:  1923 

16

Typical Procedure for Microwave Reaction.
A quartz reactor was charged with phosphine-borane 4 (50 mg, 0.24 mmol) and an excess of methylvinylketone (97 µL, 1.20 mmol). The reactor was placed into the microwaves device and the mixture was stirred for 30 min at 80 °C. Then the solution was cooled to r.t. The crude product was directly purified on silica gel chromatography (CH₂Cl₂). The product was dried under oil pump vacuum, affording phosphine-borane 8 as a white powder in 53% yield (36 mg). Mp 71 °C. ³¹P NMR (101.25 MHz, CDCl₃): δ = 26.68 (qm, ¹ J _PB = 73.9 Hz). ¹H NMR (250.13 MHz, CDCl₃): δ = 2.65 (dt, 2 H, ³ J _HH = 7.5 Hz, ³ J _HP = 8.2 Hz), 2.11 (s, 3 H), 1.90-1.65 (m, 14 H), 1.40-1.15 (m, 10 H), 0.24 (q, 3 H, ¹ J _BH = 72.5 Hz). ¹³C NMR (100.61 MHz, CDCl₃): δ = 207.31 (d, ³ J _CP = 10.9 Hz), 38.30 (s), 32.30 (d, ¹ J _CP = 33.0 Hz), 30.20 (s), 27.19 (d, ³ J _CP = 10.9 Hz), 27.17 (s), 26.87 (d, ⁴ J _CP = 2.3 Hz), 26.30 (s), 12.42 (d, ¹ J _CP = 33.9 Hz). ¹¹B NMR (128.38 MHz, C₆D₆): δ = -39.8 (dq, ¹ J _BP = 73.9 Hz, ¹ J _BH = 72.5 Hz). HRMS: m/z calcd for [M - H]⁺ = 281.22056; found: 281.2220; m/z calcd for [M - BH₃]⁺ = 268.19560; found: 268.1967. Anal. Calcd (%) for C₁₆H₃₂BOP: C, 68.10; H, 11.43. Found: C, 67.88; H, 11.77.

17

Typical Procedure for Oil Bath Reaction.
An oven-dried schlenk tube was charged with phosphine-borane precursor 1 (1 g, 5 mmol). After three cycles of oil pump vacuum/nitrogen, cyclopent-2-enone (504 µL,
6 mmol) was added under nitrogen flow. At last, toluene (1 mL) was added to the solution. The mixture was stirred for 24 h at 50 °C, then cooled to r.t. and directly purified on silica gel chromatography (CH₂Cl₂-EtOAc, 95:5). The product was dried under oil pump vacuum, affording phosphine-borane 11 as a white solid in 74% yield (1.044 g). Mp 97 °C. ³¹P NMR (161.98 MHz, CDCl₃): δ = 22.9 (qm, ¹ J _PB = 65.9 Hz). ¹H NMR (400.13 MHz, CDCl₃): δ = 7.83-7.66 (m, 4 H), 7.60-7.40 (m, 6 H), 3.20-3.14 (m, 1 H), 2.60-2.00 (m, 6 H), 0.93 (q, 3 H, ¹ J _HB = 91.8 Hz). ¹³C NMR (62.90 MHz, CDCl₃): δ = 215.77 (d, ³ J _CP = 12.6 Hz), 132.48 (d, ² J _CP = 8.8 Hz), 132.28 (d, ² J _CP = 8.8 Hz), 131.61 (d, ⁴ J _CP = 1.9 Hz), 129.02 (d, ³ J _CP = 10.1 Hz), 128.22 (d, ¹ J _CP = 54.7 Hz), 127.82 (d, ¹ J _CP = 54.7 Hz), 39.77 (d, ² J _CP = 2.5 Hz), 38.05 (d, ³ J _CP = 5.7 Hz), 31.64 (d, ¹ J _CP = 40.2 Hz), 24.21 (d, ² J _CP = 2.5 Hz). ¹¹B NMR (128.38 MHz, CDCl₃): δ = -39.59 (dq, ¹ J _BP = 69.5 Hz, ¹ J _BH = 91.8 Hz). HRMS: m/z calcd for [M - H]⁺ = 281.12666; found: 281.1246; m/z calcd for [M - BH₃]⁺ = 268.1017; found: 268.1001. Anal. Calcd (%) for C₁₇H₂₀BOP: C, 72.37; H, 7.17. Found: C, 72.19; H, 7.17.