5-fluoro-2- (4,4,5,5, - tetramethyl-1,3,2-dioxaborolan-2-yl) benzaldehyde

 

5-fluoro-2- (4,4,5,5, - tetramethyl-1,3,2-dioxaborolan-2-yl) benzaldehyde

SYNTHESIS 94)

2-bromo-5-fluorobenzaldehyde 26.1g (129mmol), 4,4,4 ', 4', 5,5,5 ', 5'- octamethyl-2,2'-bi-1,3,2- dioxaborolane 39.2g (154mmol), N of potassium acetate 25.2g (257mmol) and [1,1'-bis (diphenylphosphino) ferrocene] dichloro palladium (II) dichloromethane adduct 5.25g (6.43mmol), It was stirred for 16 hours at 100 ℃ the N- dimethylformamide (200mL) solution.Water was added to the reaction mixture and extracted with ethyl acetate. The organic layer was dried over anhydrous magnesium sulfate, the crude product obtained was concentrated and purified by silica gel chromatography (5% -25% ethyl acetate / hexanes), the title compound 16.6g of (52%) pale yellow crystals It was obtained as a. ¹ H-NMR (300MHz, CDCl₃₎ ^δ1.38 (12H, s), 7.27 (1H, td, J = 2.7,8.1Hz), 7.65 (1H, dd, J = 2. 7,9.3Hz), 7.92 (1H, dd, J = 6.3,8.1Hz), 10.62 (1H, d, J = 3.3Hz), melting point 55-58 ℃. Starting materials

2-Bromo-5-fluorobenzaldehyde

• CAS Number 94569-84-3

 

Bis(pinacolato)diboron

4,4,4',4',5,5,5',5'-octamethyl-2,2'-Bi-(1,3,2-dioxaborolane

Identifiers
CAS Registry Number	73183-34-3
Jmol-3D images	Image
PubChem	2733548
Properties
Chemical formula	C12H24B2O4
Molar mass	253.94 g·mol−1
Melting point	137 to 140 °C (279 to 284 °F; 410 to 413 K)

  Bis(pinacolato)diboron is a boron containing two pinacolato ligands. With the formula [(CH₃)₄C₂O₂B]₂, it is a colourless solid that is soluble in organic solvents. It is a commercially available reagent for making pinacol boronic esters for organic synthesis.

Preparation and structure

This compound may be prepared by reacting tetrakis(dimethylamino)diboron with pinacol in acidic conditions.^[1] The B-B bond distance is 1.711(6) Å.^[2]

References

1. Tatsuo Ishiyama, Miki Murata, Taka-aki Ahiko, and Norio Miyaura (2004). "Bis(pinacolato)diboron". Org. Synth.; Coll. Vol. 10, p. 115
2. C.Kleeberg, A.G.Crawford, A.S.Batsanov, P.Hodgkinson, D.C.Apperley, Man Sing Cheung, Zhenyang Lin, T.B.Marder "Spectroscopic and Structural Characterization of the CyNHC Adduct of B₂pin₂ in Solution and in the Solid State" J. Org. Chem 2012, vol. 77, pp. 785.doi:10.1021/jo202127c
3. Xinyu Liu "Bis(pinacolato)diboron" Synlett 2003, pp 2442–2443. doi:10.1055/s-2003-43344
4. http://www.google.fr/patents/WO2010110400A1?cl=en&hl=fr

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////////////5-fluoro-2- (4,4,5,5, - tetramethyl-1,3,2-dioxaborolan-2-yl) benzaldehyde