7.22 Oxidation of Carbon–Boron Bonds

Mild Cu-Catalyzed Oxidation of Benzylic Boronic Esters to Ketones

“…Recent advances mean that alkylboronic esters can be readily prepared and transformed through a growing number of C–C and C–heteroatom bond-forming processes . Oxidation of such boronic esters using basic H 2 O 2 to give the corresponding alcohol is widely used (Scheme ), including in the synthesis of complex natural products . If access to the carbonyl in one step is desired, oxidation of either an alkenyl- or α-heteroatom-substituted alkylboron is required.…”

Enantio- and Diastereoselective Synthesis of Hydroxy Bis(boronates) via Cu-Catalyzed Tandem Borylation/1,2-Addition

“…Consequently, stereoselective reactions that render the syntheses of these important functional groups more efficient are highly desirable. 1 Addition of chiral non-racemic alkyl-metal reagents to carbonyls provides a direct approach for the enantioselective generation of chiral alcohols bearing a vicinal stereogenic center. 2 However, chiral organometallic sp 2 -carbon nucleophiles (e.g., Grignards and organolithiums) 3 are generally preformed, air and moisture sensitive reagents that carry limited functionality, and are generated under cryogenic conditions to minimize enantiomerization.…”

“…Enantioselective methods for the preparation of alcohols and sp 3 -organoborons are important in the chemical synthesis of chiral bioactive molecules. Consequently, stereoselective reactions that render the syntheses of these important functional groups more efficiently are highly desirable . Addition of chiral nonracemic alkyl-metal reagents to carbonyls provides a direct approach for the enantioselective generation of chiral alcohols bearing a vicinal stereogenic center .…”

Palladium-Catalyzed Reactions of Allylic Boronic Esters with Nucleophiles: Novel Umpolung Reactivity

“…1 In addition, their air and moisture stability, ease of preparation, and low toxicity has further contributed to the popularity of these important reagents. For example, allylic boronic esters have been widely utilized in allylation reactions of aldehydes 2 and ketones 3 as well as palladium-catalyzed cross-couplings with aryl halides 4 and allylic carbonates.…”