Zinc Borohydride

使用zinc borohydride is unique because of the better coordination ability of Zn2+, which imparts selectivity in hydridetransferring reactions. Zinc borohydride is moderately stable in ethereal solution and has many applications in organic synthesis. Zinc borohydride, as a nonconventional hydride transferring agent, has been reported as an efficient chemo-, regio- and stereoselective reducing agent in several complex substrates. It can be used in a range of aprotic solvents such as, THF, Et2O and DME. Several combination reducing systems of Zn(BH4)2 such as Zn(BH4)2/TMEDA, Zn(BH4)2/Me3SiCl, Zn(BH4)2/ TFA/DME, Zn(BH4 ) 2 /H2O, 1Zn(BH4 ) 2 /Al 2O3 , and Zn(BH4)2/C are interesting and have been used for different reduction purposes.

製造方法Zinc borohydride (Zn(BH4)2) needs to be prepared by in situ reaction, anhydrous zinc chloride is reacted with sodium borohydride in anhydrous ether solvent.

The preparation steps of Zinc Borohydride are as follows[1]:step 1: commercially available anhydrous Zinc Chloride (ca. 10 g) in a 200 mL flask was fused three or four times under reduced pressure and then anhydrous ether (ca. 100 mL) was added.step 2: The mixture was refluxed for 1–2 h under argon and allowed to stand at 23 °C.step 3: The supernatant sat. solution of ZnCl2 (0.69 M) in ether (80 mL; 55 mmol) was added to a stirred suspension of Sodium Borohydride (4 g; 106 mmol) in anhydrous ether (300 mL).step 4: The mixture was stirred for 2 d and stored at rt under argon. The supernatant solution was used for reduction.