Chiral N-phosphonyl imine chemistry: asymmetric additions of malonate-derived enolates to chiral N-phosphonyl imines for the synthesis of β-aminomalonates

Chiral N-phosphonyl imine chemistry: asymmetric additions of glycine enolate to diphenyl diamine-based phosphonyl imines

“…Among these methods the reaction of chiral imines with glycine enolate has become one of the most powerful and practical tool for this synthesis [23][24][25]. Very recently, we established (1R,2R)-diamino-cyclohexane based phosphonyl imine chemistry [26][27][28][29][30][31][32][33][34] and developed an efficient procedure for the asymmetric synthesis of α-β diamino esters with good to excellent yields and diastereoselectivity [34].…”

“…Later, the replacement of (1R,2R)-1,2-diphenylethylene diamine with (1R,2R)-diaminocyclohexane resolved this problem and the (1R,2R)-diaminocyclohexane based chiral phosphonyl imines with different N-protecting groups were successfully utilized in many nucleopholic addition reactions [26][27][28][29][30][31][32][33][34]. Nevertheless, the 1,2-diphenylethylene diamine based phosphonyl imines are still of great value since they can extend structure scope of this important phosphonyl imines.…”

Asymmetric C–C Bond Formation between Chiral N‐Phosphonyl Imines and a Nickel(II)‐Complexed Glycine Schiff Base Provides Efficient Synthesis of α,β‐syn‐Diamino Acid Derivatives

“…10b In 2009, we studied the asymmetric reactions of N -(diphenylmethylene) glycine ester-derived enolate with two N -phosphonyl imines that are based on vicinal diamino-diphenylethane and diaminocyclohexane, but that method was limited to the synthesis α,β- anti -diamino esters as mentioned previously. 6d,7b Moreover, that synthesis required at least 5.0 equiv of N -(diphenylmethylene) glycine ester enolate for complete conversion, good diastereoselectivity and yields for most substrates. In addition, the formation of minor diastereoisomers and impurities was clearly observed by crude NMR determination.…”

“…6d,7b Under that system, (2 R ,3 S ) and/or (2 S ,3 R )-isomers α,β- syn -diamino esters were either formed in tiny amounts or not formed at all. In this communication, we are pleased to present that the asymmetric reaction of chiral N -phosphonyl imines with Ni(II) complexed glycine-derived enolate 8–9 can lead to formation of the latter isomers of α,β- syn -diamino ester analogs; 6d,7b this synthesis was achieved through the GAP chemistry process without using chromatography and recrystallization to give excellent yields and complete diastereoselectivity as shown in Table 1 and represented by Scheme 1.…”

“…and chemical properties of reagents and resulting products can be readily adjusted. 6–7 Ideally, the auxiliaries should also be cleavable under convenient conditions and recycled for re-use. 4 …”