Enantiopure β-Hydroxysulfoxide Derivatives as Novel Chiral Auxiliaries in Asymmetric Biaryl Suzuki Reactions

Abstract

[reaction: see text] Highly diastereoselective biaryl Suzuki coupling reactions of (1R)-1-(2-iodo or bromophenyl)-2-(R)-(4-tolylsulfinyl)-1-ethanol derivatives with various aryl- or naphthylboronic acids (or esters) were performed with high yields (up to 99%) and an excellent control of the axial chirality (up to 98% de).

Atropselektive Synthese axial‐chiraler Biaryle

“…Dies demonstrierte Coloberts Gruppe im Jahre 2003 (Schema 20): [144] Kupplung der Iodide (R,R)-115, die in drei Stufen aus den entsprechenden Estern zugänglich sind, mit den Boronsäuren 116 lieferte die Biaryle (R,R)-117 (mit unbekannter absoluter Achsenkonfiguration) in hohen bis ausgezeicheten Ausbeuten (bis 99 %) unter Neben der Chiralitätachse enthalten viele Biaryl-Naturstoffe noch zusätzliche Stereozentren, die den atropselektiven Aufbau der Biarylachse steuern können. Zwei Beispiele für solche (allerdings sehr spezielle) Ansätze mit interner asymmetrischer Induktion sind im Folgenden beschrieben.…”

“…[145][146][147] Das Perylenchinon Calphostin A ((P)-120), ein potenter Proteinkinase-C-Inhibitor, enthält zwei chirale b-Benzoyloxypropan-Seitenketten; diese stereochemische Information nutzten Coleman et al in der atropselektiven Totalsynthese von (P)-120 (Schema 21). [144] 3 ]-Komplexes lieferte stereochemisch inkonsistente Ergebnisse (Versuche 6 und 7). Im Allgemeinen muss das elektronenziehende {Cr(CO) 3 }-Fragment an das Arylhalogenid gebunden sein, da es die oxidative Addition an Palladium(0) beschleunigt.…”

Diastereoselective Synthesis of ‐Hydroxy Sulfoxides: Enzymatic and Biomimetic Approaches

“…Chiral β-hydroxy sulfoxides are well known for their usefulness as chiral auxiliaries in asymmetric synthesis either as ligands [1] or as building blocks for the preparation of a great variety of compounds such as cyclic sulfides, [2] benzoxathiepines, [3] benzothiazepines, [4] allylic alcohols, [5] macrolides [6] and leukotrienes. [7] So far, optically active β-hydroxy sulfoxides have been obtained either by aldol-type reactions of α-sulfinyl anions with carbonyl compounds [8] or by reduction of β-keto sulfoxides with various hydride transfer agents.…”

An Asymmetric Biaryl Suzuki Cross‐Coupling Reaction: Stereogenic Benzylic Carbinols as Chiral Auxiliaries

“…[13] We report here the use of benzylic carbinols as efficient stereochemical controllers in the biaryl Suzuki coupling reaction. [14] This stereogenic alcohol was introduced by the reduction of a β-keto sulfoxide [15] in the position ortho to the aryl halide unit (Scheme 1).…”

“…Table 1. Suzuki reactions of 1-3 with 2-methoxy-1-naphthylboronic acid (4) Entry [a] Substrate Solvent Ligand Biaryl, yield (%) [b] dr [ Simultaneously to our first communication, [14] a diastereoselective Suzuki coupling between a chiral benzylic alcohol and sterically hindered arylboronic esters was reported in an approach to cyclooctadiene lignans. [19] Results and Discussion…”