Alkoxide-Catalyzed Reduction of Ketones with Pinacolborane

Abstract

The reduction of ketones with pinacolborane (4,4,5,5-tetramethyl-1,3,2-dioxaborolane) is catalyzed by 5 mol % NaOt-Bu at ambient temperature. The reaction is high yielding and general, providing complete conversion of aryl and dialkyl ketones. Although spectroscopic studies of the active hydride source in benzene-d(6) were complicated due to poor solubility, the data are consistent with the active hydride source being the trialkoxyborohydride, which is believed to be present in low concentration under the reaction conditions. Performing analogous studies in tetrahydrofuran resulted in a complex equilibrium between several different boron-containing species in which the trialkoxyborohydride compound was the major species.

Iron-Catalyzed Cross-Coupling of Unactivated Secondary Alkyl Thio Ethers and Sulfones with Aryl Grignard Reagents

“…The 1 H NMR spectroscopic data and boiling point matched that for alternative preparations. 95 Data for 28 : bp: 77-78 °C (0.5 mmHg) [lit. 96 75 °C (0.3 mmHg)].…”

Organic reactions for the electrochemical and photochemical production of chemical fuels from CO2 – The reduction chemistry of carboxylic acids and derivatives as bent CO2 surrogates

“…Silanes, [103] boranes [104] and NHC boranes [105] In this section we describe some instances of organocatalytic reduction chemistry with silanes and boranes as terminal reducing agents, as these transformations may be amenable to translation into electrochemistry-driven processes.…”

“…Pinacolborane has also been shown to catalytically reduce carbonyl compounds in the presence of NaOtBu as catalyst [104]. The proposed active reducing agent in this reaction is an in situ generated trialcoxyborohydride.…”

Alkoxide‐Promoted Selective Hydroboration of N‐Heteroarenes: Pivotal Roles of in situ Generated BH3 in the Dearomatization Process

“…MOH, MO t ‐Bu; M=Na, K) are known to be effective catalysts for a range of (dehydrogenative)silylative transformations of carbonyls, (hetero)arenes, and alkynes . However, the scope of alkali base‐promoted hydroboration has been narrow and thus limited mainly to carbonyl functions . In addition, Lewis acid–borane adducts (e.g.…”