Chiral Lithium Amido Aryl Zincates: Simple and Efficient Chemo‐ and Enantio‐Selective Aryl Transfer Reagents

Abstract

An enantioselective aryl transfer is promoted using chiral tricoordinated lithium amido aryl zincates that are easily accessible reagents and whose chiral appendage is simply recovered for reuse. The arylation reaction is run in good yields (60 % average on twenty substrates) and high enantiomeric excesses (95 % ee average). This occurs whatever the ortho, meta, or para substituent borne by the substrate and a complete chemoselectivity is observed with respect to the aldehyde function. Sensitive groups such as nitriles, esters, ketones, and enolisable substrates resist to the action of the ate reagent, warranting a large scope to this methodology.

Photoassisted Cobalt-Catalyzed Asymmetric Reductive Grignard-Type Addition of Aryl Iodides

“…In contrast, transition-metal-catalyzed asymmetric Grignard-type additions of organometallic reagents (Mg, Zn, B, etc. ) − to carbonyl groups provide better options for syntheses of benzyl alcohols with similar substituents (Figure b). Nevertheless, the stoichiometric use of organometallic reagents results in poor functional group compatibility, and to some extent, the relatively harsh conditions hinder the practical application of this reaction.…”

Ru-Catalyzed Asymmetric Addition of Arylboronic Acids to Aliphatic Aldehydes via P-Chiral Monophosphorous Ligands

“…Thus, the invention of methods for the preparing of such chiral aryl alkyl alcohols features an important role in organic synthesis. Classic methods for constructing such chiral molecules include asymmetric hydrogenation of ketones [11][12][13], asymmetric hydrogen transfer reduction of ketones or unsaturated ketones [14][15][16][17][18][19][20][21], along with the asymmetric addition of organometallic reagents to aldehydes [22][23][24]. As an alternative, strategies via the asymmetric homologation reaction [25][26][27][28], tandem Michael-MPV reaction and subsequent reductive desulfurization [29], as well as the asymmetric addition of aldehydes with arylboronic acids were also established [30,31].…”

“…Similar to the organometallic reagents, the addition of organoborons to carbonyl compounds allows for the generation of chiral alcohols in direct and effective ways. Compared with the disadvantages of organometallic reagents [22][23][24], the organoborons feature the advantages of easy manipulation, low toxicity and good functional group tolerance [35], which has attracted great attention [36][37][38] since Miyaura reported the first Rh-catalyzed asymmetric addition of arylboronic acid to aldehydes in 1998 [39]. For example, metals including Rh [40][41][42][43][44][45][46][47][48], Ru [49], Ni [50], Co [51] and Pd [52][53][54] have been intensively explored in this regard recently.…”