Enantioselective Alkylation of Glycine Imine Promoted by Amino‐Acid‐Derived Phosphonium Salts

Abstract

Chiral phosphonium salts derived from natural amino acids were prepared and appliedtot he asymmetric alkylation reaction of glycine imine with substituted benzyl bromides, and the desired alkylationp roducts were obtained in high yields and with excellent enantioselectivities.

Stereoselective Synthesis of CF3‐Containing Spirooxindoles via 1,3‐Dipolar Cycloaddition by Dipeptide‐Based Phosphonium Salt Catalysis

“…[9] The groups of Maruoka [10] and Ooi [11] have recently made major breakthroughs in this field. In recent years, a number of phosphonium salt catalysts derived from chiral amino acids and their initiatory applications in asymmetric conjugate addition and substitution reactions were demonstrated by the groups of Zhao, [12] Lu [13] and others. [14,15] It is worth noting that the amino acid-based phosphonium salts have high adjustability, but their application in asymmetric synthesis has so far been rare.…”

Highly Enantioselective Synthesis of Fused Tri‐ and Tetrasubstituted Aziridines: aza‐Darzens Reaction of Cyclic Imines with α‐Halogenated Ketones Catalyzed by Bifunctional Phosphonium Salt

“…[10a] Quite recently, Tr ost developed aZ n-ProPhenol catalyzed aza-Darzens reaction of chlorinated aromatic ketones with N-Boc aldimines,p roviding an ovel method for constructing trisubstituted chiral aziridine motifs. [16] More recently,t he groups of Zhao [17] and Lu [18] derived several phosphonium salt catalysts from amino acids and initially demonstrated their effectiveness in asymmetric Scheme 1. Therefore,i ti sh ighly desirable to explore autilitarian strategy to fill this void.…”

“…[12,13] Thekey breakthroughs in this field were recently reported by the groups of Maruoka [14] and Ooi. [16] More recently,t he groups of Zhao [17] and Lu [18] derived several phosphonium salt catalysts from amino acids and initially demonstrated their effectiveness in asymmetric Scheme 1. [16] More recently,t he groups of Zhao [17] and Lu [18] derived several phosphonium salt catalysts from amino acids and initially demonstrated their effectiveness in asymmetric Scheme 1.…”

“…[12,13] Thekey breakthroughs in this field were recently reported by the groups of Maruoka [14] and Ooi. [16] More recently,t he groups of Zhao [17] and Lu [18] derived several phosphonium salt catalysts from amino acids and initially demonstrated their effectiveness in asymmetric conjugate additions and substitution reactions.N otably,s uch amino-acid-based phosphonium salts possess remarkably high tunability,but their utilization in asymmetric synthesis is rare to date.Aspart of our research interest in the development of asymmetric synthetic methods catalyzed by amino-acid-based organocatalysts, [19] we envisioned that employment of highly tunable bifunctional phosphonium salts may result in apractical asymmetric aza-Darzens cyclization protocol to construct densely tri-and tetrasubstituted aziridine cores (Scheme 2). [16] More recently,t he groups of Zhao [17] and Lu [18] derived several phosphonium salt catalysts from amino acids and initially demonstrated their effectiveness in asymmetric conjugate additions and substitution reactions.N otably,s uch amino-acid-based phosphonium salts possess remarkably high tunability,but their utilization in asymmetric synthesis is rare to date.Aspart of our research interest in the development of asymmetric synthetic methods catalyzed by amino-acid-based organocatalysts, [19] we envisioned that employment of highly tunable bifunctional phosphonium salts may result in apractical asymmetric aza-Darzens cyclization protocol to construct densely tri-and tetrasubstituted aziridine cores (Scheme 2).…”

“…Also,abroad range of cyclic abromobenzopyrones with different substituents in the ortho-, meta-, or para-position of the phenyl ring were found to be viable substrates,d elivering the desired products 11 a-n in high yields (86-99 %) with high ee values (91-> 99.9 %). Moreover,ab iologically active compound (18), which has potential activity as an HIV-1 inhibitor, [2e-h] was prepared in high yield with good stereoselectivities by using this aza-Darzens protocol (Scheme 4). Thea bsolute configurations of these fused spiro-aziridine products were assigned based on X-ray crystal structural analysis of 10 a.…”