Super Hydrides.
Abstract
The unusual reactivity of lithium triethylborohydride (Super Hydride) encouraged us to examine the selective reduction properties of a number of new reducing agents. Just as the replacement of hydrogen atoms in lithium borohydride (LiBH4) with alkyl groups increases the reactivity of the reagent, substitution with alkoxy groups diminishes the reactivity. Thus, the trialkoxyborohydrides (K (RO)3BH) are very mild reducing agents. A series of potassium trialkoxyborohydrides were prepared in refluxing tetrahydrofuran from the trialkoxyborane and potassium hydride. In a similar fashion, a number of monoalkyldialkoxyborohydrides (KR (OR)2BH) were prepared from cyclic boronate esters and potassium hydride. We also discovered that potassium hydride reacts readily with a variety of B-alkoxy-9-BBN derivatives to afford the corresponding potassium dialkylalkoxyborohydrides (KR(OR)2BH). Thus we can now prepare the entire series of alkylalkoxyborohydrides: KR3Bh, KR2(OR)BH, KR(OR)2BH and K(OR)3BH. Although the full potentialities of these reagents are yet to be explored, preliminary studies on the reduction of cyclic ketones have shown encouraging stereoselectivities. Originator-supplied keywords include: Super Hydride, Trialkoxyborohydrides, Thexylchloroborane, Selective Reductions, Borane-Methyl Sulfide, Lithium Borohydride, Carboxylic Acids, ALdehydes, Alkydialkoxyborohydride, Dialkylalkoxyborohydride.
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 07, 1985
- Accession Number
- ADA153499
Entities
People
- H. C. Brown
Organizations
- Purdue University