Asymmetric catalytic addition of diorganozinc reagents to imines: Scope and application

Abstract

Abstract:The copper-catalyzed diorganozinc addition to N-diphenylphosphinoylimines was shown to proceed with a very high degree of enantiocontrol if the reaction was run in the presence of Me-DuPHOS monoxide ligand (BozPHOS). The scope of the reaction is described as well as our efforts to identify the nature of the enantioactive metal complex responsible for the high asymmetric induction.

Stereoselective Synthesis of α‐Branched Amines by Nucleophilic Addition of Unstabilized Carbanions to Imines

“…The imines are generated in situ from aromatic and aliphatic a-amidosulfones. The reaction proceeds with high yield and a high degree of enantiocontrol (Table 1. 8). However, the scope of the reaction is limited to aryl-substituted imines.…”

“…This modification opened the door to copper-, rhodium-, iridium-, and palladium-catalyzed nucleophilic addition chemistry. The increase in electrophilicity as a function of the electron-withdrawing ability of the activating group can be appreciated by comparing the ab initio calculations of the LUMO energy of various electrophiles to that of the imine derived from benzaldehyde and N-methylamine (Figure 1.1) [8]. These results suggest that N-acyl imines are substantially more electrophilic than the other types of imines bearing alkyl or aryl groups.…”

Tetrabenzylhafnium as a New Organometallic Reagent for Imine Addition Resulting in α‐Branched Amines

“…[2,3] In the past decades, several main group metals and early transition metals have been developed as organometallic nucleophiles for addition reactions to imines, especially in their asymmetric forms. Pioneering work in this area included the study of organolithium, [4] Grignard, [5] and dialkylzinc [6] reagents. Following these early successes, more organometallic reagents, such as organostannanes, [7] allylsilanes, [8] aryltitaniums, [9] alkylcoppers, [10] and arylboroxines, [11] were explored for addition reactions to imines, but such reactions usually required additional catalysts.…”

“…It is noteworthy that hafnium is yet another metal that can be used as an organometallic reagent in nucleophilic addition reactions, in addition to previously reported lithium, magnesium, zinc, stannum, silicon, copper, and boron. [4][5][6][7][8][9][10][11] Scheme 1. Tetrabenzylhafnium nucleophilic addition to imines.…”

Reactions of Aldehydes and Ketones and their Derivatives

“…Copper-catalysed enantioselective addition of diorganozincs to phosphinoylimines ee has been reported, 42 as has enantioselective addition of diethylzinc to N -acylaldimines. 43 7 Asymmetric addition of organometallic reagents to imines, to produce useful optiee cally active amines, has been reviewed.…”