(Pyridine)(tetrahydroborato)zinc Complex, [Zn(BH4)2(py)], as a New Stable, Efficient and Chemoselective Reducing Agent for Reduction of Carbonyl Compounds
Bull. Korean Chem. Soc. 24(4), 453-459 (2003) (http://journal.kcsnet.or.kr/publi/bul/bu03n4/453.pdf)
(http://journal.kcsnet.or.kr/publi/bul/bu03n4/453.pdf)
Abstract
(Pyridine)(tetrahydroborato)zinc complex, [Zn(BH4)2(py)], as a stable white solid, was prepared quantitatively by complexation of an equimolar amount of zinc tetrahydroborate and pyridine at room temperature. This reagent can easily reduce variety of carbonyl compounds such as aldehydes, ketones, acyloins, (https://www.thevespiary.org/rhodium/Rhodium/hive/hiveboard/picproxie_docs/000435007-file_lwwo.gif)-diketones and (https://www.thevespiary.org/rhodium/Rhodium/hive/hiveboard/picproxie_docs/000435007-file_lwwo.gif),(https://www.thevespiary.org/rhodium/Rhodium/hive/hiveboard/picproxie_docs/000435007-file_feqa.gif)-unsaturated carbonyl compounds to their corresponding alcohols in good to excellent yields. Reduction reactions were performed in ether or THF at room temperature or under reflux conditions. In addition, the chemoselective reduction of aldehydes over ketones was accomplished successfully with this reducing agent.
Some may find this interresting (posted it here, since this was the most closely related thread still open...):
Use of Zinc Borohydride in Reductive Amination: An Efficient and Mild Method
for N-Methylation of Amines
Sukanta Bhattacharyya et. al.
J. Chem. Soc. Perkin Trans. 1, pp. 1-2 (1994) (http://bobo_bee.tripod.com/Hive/papers/2_red_am.djvu)
(http://bobo_bee.tripod.com/Hive/papers/2_red_am.djvu)
An efficient method for the reductive methylation of amines using paraformaldehyde, zinc chloride and zinc borohydride is described.
This can be an alternative to:
https://www.thevespiary.org/rhodium/Rhodium/chemistry/amphetamine.methylation.html (https://www.thevespiary.org/rhodium/Rhodium/chemistry/amphetamine.methylation.html)
PiHKAL #109 MDMA (http://www.erowid.org/library/books_online/pihkal/pihkal109.shtml)
(http://www.erowid.org/library/books_online/pihkal/pihkal109.shtml)
Tihkal #50. NMT (http://www.erowid.org/library/books_online/tihkal/tihkal50.shtml)
(http://www.erowid.org/library/books_online/tihkal/tihkal50.shtml)
With this Zn(BH4)2 method nPr-NH2 is monomethylated w/ 70% yield.
Reductive amination w/ Zn(BH4)2 was discussed in:
Post 122811 (https://www.thevespiary.org/talk/index.php?topic=12566.msg12281100#msg12281100)
(dormouse: "reductive amination with NaBH4 -- why *does* it work? -rev drone", Serious Chemistry)
Post 69528 (missing)
(spric: "reductive amination with Zn(BH4)2", Methods Discourse)
Preparations of Zn(BH4)2
Post 394840 (https://www.thevespiary.org/talk/index.php?topic=12018.msg39484000#msg39484000)
(demorol: "Preparation of zinc borohydride solution", Novel Discourse)
Reduction of Conjugated Nitroalkenes with Zinc Borohydride.
A Mild Method for Converting Monosubstituted Nitroalkenes to Nitroalkanes and Disubstituted Ones to Oximes
Brindaban C. Ranu and Rupak Chakraborty
Tetrahedron 48(25), 5317-5322 (1992) (https://www.thevespiary.org/rhodium/Rhodium/pdf/znbh4.nitroalkenes2oximes.pdf)
(https://www.thevespiary.org/rhodium/Rhodium/pdf/znbh4.nitroalkenes2oximes.pdf)
Abstract
Mono-?-substituted conjugated nitroalkenes are readily reduced by zinc borohydride in 1,2-dimethoxyethane to the corresponding nitroalkanes, whereas the disubstituted ones furnish the corresponding oximes in excellent yields.
Reductive Amination with Zinc Borohydride. Efficient, Safe Route to Fluorinated Benzylamines
Sukanta Bhattacharyya, Arindam Chatterjee and John S. Williamson
Synthetic Communications 27(24), 4265-4274 (1997) (https://www.thevespiary.org/rhodium/Rhodium/pdf/redamin.znbh4.fluorobenzylamines.pdf)
(https://www.thevespiary.org/rhodium/Rhodium/pdf/redamin.znbh4.fluorobenzylamines.pdf)
Abstract
Fluorinated benzylamines are synthesized in high yields by reductive alkylation of secondary amines with appropriate fluoroaldehydes using a combination of zinc chloride and zinc borohydride. The present method method offers an alternative to toxic sodium cyanoborohydride and is adaptable to multigram-scale preparations.