Regio‐ and Stereoselective Homologation of 1,2‐Bis(Boronic Esters): Stereocontrolled Synthesis of 1,3‐Diols and Sch 725674

Abstract

Abstract1,2‐Bis(boronic esters), derived from the enantioselective diboration of terminal alkenes, can be selectively homologated at the primary boronic ester by using enantioenriched primary/secondary lithiated carbamates or benzoates to give 1,3‐bis(boronic esters), which can be subsequently oxidized to the corresponding secondary‐secondary and secondary‐tertiary 1,3‐diols with full stereocontrol. The transformation was applied to a concise total synthesis of the 14‐membered macrolactone, Sch 725674. The nine‐step synthetic route also features a novel desymmetrizing enantioselective diboration of a divinyl carbinol derivative and high‐yielding late‐stage cross‐metathesis and Yamaguchi macrolactonization reactions.

Carbohydrate/DBU Cocatalyzed Alkene Diboration: Mechanistic Insight Provides Enhanced Catalytic Efficiency and Substrate Scope

“…Catalytic enantioselective 1,2-diboration of alkenes 1,2 is a valuable strategy for transforming alkenes to a variety of functionalized products. 3 Most often, this process operates by transition-metal based activation of a diboron reagent, followed by reaction of a resulting metal-boryl complex with the unsaturated substrate. 4 Alternatively, and aligned with seminal studies by Hoveyda 5 on the Lewis-base catalyzed activation of diboron reagents for nucleophilic conjugate addition reactions, Fernandez made the remarkable discovery that 1,2-diboration of unactivated alkenes could be catalyzed by simple metal alkoxides.…”

Synthesis of 1,3‐Bis‐(boryl)alkanes through Boronic Ester Induced Consecutive Double 1,2‐Migration

“…Bis‐(boryl)alkanes, an interesting subclass, have attracted increasing attention as synthetic precursors in organic synthesis enabling multiple C−C and C–heteroatom bond construction . Although many methods for accessing 1,1‐ and 1,2‐bis‐(boryl)alkanes have been reported, general methods for the synthesis of 1,3‐bis‐(boryl)alkanes are rare . Therefore, an efficient and general procedure for the preparation of 1,3‐bis‐(boryl)alkanes is demanded.…”

Blickpunkt Synthese: Polyketide am Fließband

“…1. in 1,2-oder 1,3-Abstand stereoselektiv herstellen. 2,[9][10][11][12][13] um Alkylketten mit stereogenen Zentren aufzubauen. Besonders attraktiv daran ist, dass sich die verschiedenen Bausteine in einer Reaktionssequenz herstellen lassen und gleichzeitig C-C-Bindungen und Stereozentren entstehen.…”