83049-24-5

Upstream product

• 78688-64-9 (S)-N-benzylidene-1-t-butoxycarbonylethylamine 
• 100-52-7 benzaldehyde 
• 21691-50-9 Ala-OtBu 
• 78688-66-1 1-<(S)-1-(tert-butoxycarbonyl)ethyl>-(3S,4R)-3-azido-4-phenylazetidin-2-one 

Downstream Products

• 78688-67-2 1-<(S)-1-(tert-butoxycarbonyl)ethyl>-(3S,4R)-3-<(3'R,4'S)-3-azido-4-phenylazetidin-2-on-1-yl>-4-phenylazetidin-2-one 
• 78738-83-7 (S)-2-((3R,4S,3'S,4'R)-3-Acetylamino-2,2'-dioxo-4,4'-diphenyl-[1,3']biazetidinyl-1'-yl)-propionic acid tert-butyl ester 
• 107079-82-3 (S)-2-((3R,4S,3'S,4'R)-3-Amino-2,2'-dioxo-4,4'-diphenyl-[1,3']biazetidinyl-1'-yl)-propionic acid tert-butyl ester 
• 78688-68-3 1-<(S)-1-(tert-butoxycarbonyl)ethyl>-(3S,4R)-3-(benzylideneamino)-4-phenylazetidin-2-one 
• 78688-68-3 (S)-2-((3S,4R)-2-Oxo-4-phenyl-3-{[1-phenyl-meth-(E)-ylidene]-amino}-azetidin-1-yl)-propionic acid tert-butyl ester 

Relevant academic research and scientific papers

Remarkable Effects of Lone Pair-Lone Pair Interactions on the Extremely Stereoselective Cycloaddition of Azidoketene to Chiral 3-Imino-β-lactams

The stereoselective cycloaddition of azidoketene to cis-3-imino-β-lactams 1, 2, and 3, trans-3-imino-β-lactam 4, and cis-3-iminoazetidine 5 were carried out.It was found that the reactions of 1, 2, and 3 proceeded with > 99.5 percent stereoselectivity to give bis-β-lactams 9, 14, and 19, respectively.The reaction of 4 gave a bis-β-lactam 20 with 62 percent de, and the reaction of 5 gave a β-lactamazetidine 21 with 32 percent de including the asymmetry in the opposite direction.These results clearly indicate that, in addition to the conventional steric effects, the lone pair-lone pair interaction of β-lactam oxygen with the intermediate betaine's oxygen is the crucial factor for the extremely stereoselective cycloaddition of azidoketene to 1, 2, and 3.Possible mechanisms for these stereoselective cycloadditions are proposed.The X-ray crystal structure of 3a and the calculated energy-minimum conformations of 3a, 4, and 5 with MODEL-MM2-ROTOCHEM programs are provided.

Effective Method for the Asymmetric Synthesis of Bis-β-lactams by the Cycloaddition of Azidoketen to Benzylideneamines Bearing a Chiral β-Lactam Backbone

Extremely high stereoselectivity was observed in the asymmetric cycloaddition of azidoketen to 1--3-benzylideneamino-4-phenylazetidin-2-ones, which gave rise to the formation of optically pure bis-β-lactams.