Imines N-diphenylphosphinoyl

The most effective route to aminoalcohol (493) was established by screening various stereochemically homogeneous N,N-disubstituted-, N-monosubstitut-ed-amino alcohols and iminoalcohols as chiral additives to promote asymmetric addition of alkylzinc to N-diphenylphosphinoyl imine (492). The addition reactions that were performed in the presence of this compound resulted in excellent enantioselectivity (Figure 94a). 

Charette offers a way around some of these problems by demonstrating two alternative three-step methods. For aromatic aldehydes, an N-diphenylphosphinoyl imine can be preformed and isolated. Subsequent treatment with 2.0 equiv of Et2Zn in the presence of catalytic Cu(OT02... 

N-diphenylphosphinoyl imines also react with dialkylzinc in the presence of stoichiometric or catalytic amounts of different chiral see Chiral) ligands (Scheme 24). Acid hydrolysis of the resulting phosphinamides occurs without racemization and gives enantiomerically enriched primary amines. The allylation of various cyclic imines was obtained with high enantioselectivity seeElectrophile), 11 to 99% e.e., in the presence of lithiated bis-oxazoline ligands (Scheme 25). 

Addition of lithiated alkoxy ethynyl anion with chiral Al-sulfinyl imines proceeds with dr >95 5, which can be reversed in the presence of BF3. Excellent diastereoselec-tivity has been reported for zinc-mediated addition of methyl and terminal alkynes to chiral IV-f-butanesulfinyl ketimines (to form 3-amino oxindoles). Zinc-BINOL complexes have been used to achieve enantioselective addition of terminal alkynes to N-(diphenylphosphinoyl)imines (up to 96% cc) and terminal 1,3-diynes to IV-arylimines to trifluoropyruvates (up to 97% yield and 97% ee). ... 

Asymmetric addition to ketimine in a reagent controlled manner has seldom been reported, even by 2008. When we investigated the potential for tbis asymmetric addition around 1992, there were no known examples. In 1990, Tomioka et al., reported the first asymmetric addition of alkyl lithium to N-p-methoxyphenyl aldo-imines in the presence ofa chiral (3-amino ether with 40-64% ee [8] (Scheme 1.11). In 1992, Katritzky reported the asymmetric addition of Et2Zn to in situ prepared N-acyl imine in the presence of a chiral (3-amino alcohol with 21-70% ee [15] (Scheme 1.12). In the same year, Soai et al., reported the asymmetric addition of dialkylzinc to diphenylphosphinoyl imines in the presence of chiral (3-amino alcohols with 85-87% ee [16] (Scheme 1.13). These three reports were, to the best of... 

Chiral amines, ArCH(R)NH2, can be prepared by addition of a dialkylzinc to A-(diphenylphosphinoyl)imines, ArCH=N—P(=0)Ph2, using a suitable auxiliary, followed by acid hydrolysis to cleave the phosphorus moiety. A series of 2-azanorbornylmethanols (65) give ee% up to 92%, and they also induce some enantioselectivity in additions to benzaldehyde. A highly organized transition state with two zincs is proposed one coordinates the nitrogens of substrate and catalyst and the other coordinates the oxygens. 

Chiral amines, ArCH(R)NH2, can be prepared by addition of a dialkylzinc to A-(diphenylphosphinoyl)imines, ArCH=N—P(=0)Ph2, using a suitable auxiliary, followed by acid hydrolysis to cleave the phosphorus moiety. A series of... 

P ligand first by adding one C-NH bond in a reductive amination process, and then forming the second C=N bond and finally the third-generation complex 14 (Fig. 40). This new class of catalyst was effective in the rapid reduction of N-diphenylphosphinoyl-activated imines containing phosphinoyl groups in >99 % e.e. (Fig. 41) [126, 127]. 

The addition of BF3-OEt2 to an a-phosphorylated imine results in the 1,3-transfer of a diphenylphosphinoyl group, with resultant migration of the C-N=C triad. This method is less destructive than the thermal rearrangement. The decomposition of dimethyldioxirane in acetone to methyl acetate is accelerated with BF3 OEt2, but acetol is also formed. Propene oxide undergoes polymerization with BF3-OEt2 in most solvents, but isomerizes to propionaldehyde and acetone in dioxane. ... 

---