The simple and selective synthesis of 3-amino-2,2-difluorocarboxylic esters and difluoro-β-lactams using ethyl bromodifluoroacetate in the presence of rhodium catalyst

Treatment of imines (5) with ethyl bromodifluoroacetate (1) and Et₂Zn in the presence of RhCl(PPh₃)₃ in anhydrous medium gave difluoro-β-lactams (7) in good to excellent yields, while 3-amino-2,2-difluorocarboxylic esters (6) were obtained in good yields by adding MgSO₄·7H₂O to the reaction medium.     

Indium(I) iodide promoted highly selective 1,2-addition of allyl and benzyl groups to α,β-unsaturated nitriles under sonication: a new synthesis of conjugated imines

Allyl and benzyl bromides react with α,β-unsaturated nitriles in the presence of indium(I) iodide under sonication to produce the corresponding allylated and benzylated conjugated imines involving exclusive addition of the allyl/benzyl group to the CN moiety.     

Efficient preparation of Ellman’s imines from trifluoromethyl ketones promoted by zirconium(IV) tert-butoxide

An efficient synthesis of chiral N-tert-butanesulfinyl trifluoromethyl ketimines by using zirconium(IV) tert-butoxide is described. Compared to conventional titanium(IV) ethoxide, this protocol gave better result especially for sterically hindered ketones. In addition to the high reactivity, a high degree of enantiopurity of the N-tert-butanesulfinyl group is retained.     

The study of Friedel-Crafts alkylation reaction of thiophenes with glyoxylate imine catalyzed by Fe(III): an easy access to α-aminoesters

A Friedel-Crafts alkylation reaction of thiophenes with glyoxylate imine was developed to give α-aminoesters. In the presence of FeCl₃·6H₂O as the catalyst, various α-aminoesters were prepared with moderate to high yields (up to 95%) except for some special substrates.     

Efficient synthesis of polysubstituted pyrrole-3-carbonitriles via reactions of 1,1-dicyano-2,3-diarylcyclopropanes with aromatic imines

Co(ClO₄)₂ smoothly catalyzed the reactions of 1,1-dicyano-2,3-diarylcyclopropanes with aromatic imines to give the novel polysubstituted pyrrole-3-carbonitriles bearing an 2-arylidenimino group in good to high yields in refluxing THF.     

Synthesis of new imines and amines containing organosilicon groups

The Peterson olefination reaction of terephthalaldehyde with tris(trimethylsilyl)methyl lithium, (Me₃Si)₃CLi, in THF at 0 °C gives 4-[2,2-bis(trimethylsilyl)ethenyl]benzaldehyde (1) and 4,4-bis[2,2-bis(trimethylsilyl)ethenyl]benzene (2). The new aldehyde (1) reacts with variety of amines in ethanol to afford the corresponding imines (3) containing vinylbis(trimethylsilyl) group. The newly synthesized imines (3) can be completely converted into amines containing vinylbis(trimethylsilyl) group with an excess amount of NaBH₄. In the case of N-[4-(2,2-bis(trimethylsilyl)ethenyl)benzyl]-2,6-dimethylaniline LiAlH₄ was used as a reducing agent in THF.     

Mannich-Type Reactions of Alkylzinc Reagents

Mannich-type reactions involving alkylzinc reagents have been developed using different strategies. We show that the addition of these organometallic species to sulfonyl imines occurs upon simple heating and affords Mannich products in moderate to excellent yields (14 examples, 30–99 %). Interestingly, N-alkyl imines were also found to be suitable partners after activation as an acyliminium by acetyl chloride (12 examples, 49–86 %) or, more originally, by TMSCl (14 examples, 26–87 %). These methods proved complementary, leading to the preparation of both N-protected secondary or tertiary amines and N-unprotected secondary amines in good yields, with an increased eco-compatibility, and under simple conditions.