Stereoregulated synthesis of β-lactams from schiff bases derived from threonine esters

Advances in the chemistry of ?-lactam and its medicinal applications

“…For example, 3-azido-β-lactam 5a (R = triphenylsilyl = TPS) was obtained in 64% yield and 19:1 dr ( 5a:6a ) using imine 4a derived from ( R )- O -TPS-threonine benzyl ester and cinnamaldehyde (Scheme 2). 37 The stereoselectivity of this reaction was found to depend critically on the bulkiness of the hydroxyl protecting group. Thus, the reaction of 4b (R = t -butyldimethylsilyl = TBS) gave 5 b with 9:1 dr ( 5b:6b ) and that of 4c (R = H) afforded a 1:1 mixture of 5c and 6c .…”

Asymmetric electrocyclic reactions

“…Enantiomerically-enriched imines derived from both chiral aldehydes and amines have been shown to be effective in controlling the diastereoselectivity of the Staudinger reaction. A number of chiral amines have been utilized to this end, including those derived from D-threonine, 107 L-threonine, 108 phenylethylamine, 109,110 L-alanine, 111 and (2S,5S)-2,5-hexanediol. 112,113 The last example is noteworthy since it employs a chiral hydrazone yielding N-amino b-lactams with very high diastereoselectivity and an interesting temperature-dependence (Scheme 17).…”

Synthesis and Antimicrobial Activity of Some New Sugar-Based Monocyclic β-Lactams

“…A monocyclic β-lactam containing a carbohydrate moiety resulting from the reaction of phthalimidoacetyl chloride with the imine of D-glucosamine and cinnamaldehyde has been reported [10]. The monocyclic β-lactam derived from the imine of the amino acid D-threonine upon treatment with azidoacetyl chloride and triethylamine has been reported by Bose [11]. Gunda has reported the synthesis of monocyclic β-lactams with high diastereoselectivity [12], while Palomo and his co-workers have synthesized monocyclic β-lactams bearing carbohydrate moieties with moderate diastereoselectivity [13].…”