Extending the Scope of the B(C6F5)3‐Catalyzed CN Bond Reduction: Hydrogenation of Oxime Ethers and Hydrazones. Issue 49 (22nd October 2015)

• Record Type: Journal Article
• Authors: Mohr, Jens; Porwal, Digvijay; Chatterjee, Indranil; Oestreich, Martin
• Is Part Of: Chemistry. Volume 21:Issue 49(2015)
• Page Start: 17583
• Page End: 17586
• Publication Date: 2015-10-22
• Subjects: boron -- homogeneous catalysis -- hydrogenation -- Lewis acids -- reduction; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201503509
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: The B(C6 F5 )3 ‐catalyzed hydrogenation is applied to aldoxime triisopropylsilyl ethers and hydrazones bearing an easily removable phthaloyl protective group. The CN reduction of aldehyde‐derived substrates (oxime ethers and hydrazones) is enabled by using 1, 4‐dioxane as the solvent known to participate as the Lewis‐basic component in FLP‐type heterolytic dihydrogen splitting. More basic ketone‐derived hydrazones act as Lewis bases themselves in the FLP‐type dihydrogen activation and are therefore successfully hydrogenated in nondonating toluene. The difference in reactivity between aldehyde‐ and ketone‐derived substrates is also reflected in the required catalyst loading and dihydrogen pressure. Abstract : Digging for more : The B(C6 F5 )3 ‐catalyzed hydrogenative CN reduction is extended to aldoxime ethers and both ketone‐ and aldehyde‐derived hydrazones. Less basic aldehyde‐derived substrates require the use of an ethereal solvent to be efficiently reduced whereas more basic ketone‐derived substrates react in toluene under milder conditions (see scheme).