Asymmetric catalytic Strecker reaction of N-phosphonyl imines with Et2AlCN using amino alcohols and BINOLs as catalysts

Abstract

The asymmetric catalytic Strecker reaction of achiral N-phosphonyl imines with Et(2)AlCN has been established. Both free amino alcohols and BINOLs have been proven to be effective catalysts to afford excellent enantioselectivities and yields. The N-phosphonyl group can be readily cleaved under mild conditions and enable purification of crude products by simple washing with hexane. The cleaved N,N-dialkyl diamine auxiliary can be recovered quantitatively via n-BuOH extraction. The scope for both N-phosphonyl imines and catalysts was vastly studied for this new catalytic system.

SmI2-promoted imino-Reformatsky reaction for facile synthesis of enantioenriched β-amino acid esters

“…In recent years, a number of different chiral auxiliaries [8][9][10][11][12][13] as well as catalysts [14] has been introduced to provide the products with high stereoselectivities. Among them, the chiral sulfoxides are found as one of the best auxiliaries for the advantages of good stereodirecting and facile removal [15][16][17][18][19]. In contrast to the classical Zn-induced Reformatsky protocol, the application of other metal salts such as samarium diiodide by diastereoselective samarium enolate addition has received little attention in imino-Reformatsky reaction [9].…”

Asymmetric synthesis of α-alkenyl homoallylic primary amines via 1,2-addition of Grignard reagent to α,β-unsaturated phosphonyl imines

“…Up to now, successful examples have been achieved in aza-Henry reaction 16 , aza-Mannich reaction 17 , Grignard reaction 18 , Strecker reaction 19 and so on. Owing to their advantages in wide versatility and high efficiency, we tried to utilize this chiral auxiliary in more asymmetric addition reactions.…”

Asymmetric Synthesis of α-Amino-1,3-dithianes via Chiral N-Phosphonyl Imine-Based Umpolung Reaction Without Using Chromatography and Recrystallization

“…1–4 So far, general reagents, particularly chiral reagents that enable organic synthesis to be performed without the use of traditional purifications via chromatography or recrystallization, have not been established. 5 However, this concept would encourage the synthetic community to make more efforts on searching for greener reagents and related reactions to better serve academia and the pharmaceutical industry. It would substantially minimize the use of energy, starting materials and manpower as to save nature’s resources.…”