Stereoselective synthesis and characterization of novel trans-4-(thiophenyl)pyrazolyl-β-lactams and their C–3 functionalization

Synthesis of C2‐Formamide(thiophene)pyrazolyl‐C4’‐carbaldehyde and their Transformation to Schiff's Bases and Stereoselective trans‐β‐Lactams: Mechanistic and Theoretical Insights

“…Next, the isolated hydrazone 2 was transformed into 1‐phenyl‐3‐(3’‐carboethoxy‐2’‐formamide‐4’‐methylthio‐phen‐5’‐yl)‐1 H ‐pyrazole‐4‐carbaldehyde 3 by interacting with DMF/POCl 3 (Vilsmeier‐Haack) reagent (Scheme 1). It was expected initially that monoformylated product 3 ’ had been formed, according to previously studied Vilsmeier‐Haack reaction and our old study [24d] . But as per 1 HNMR spectrum, a broad signal for one proton observed at δ 11.49 ppm (Figure 2a) which further vanished during D 2 O exchange experiment (Figure 2b).…”

Stereoselective synthesis of β-lactams: recent examples

“…The original results were reported by Bhalla and colleagues. 34 products, using ciprofloxacin as the reference control. In addition, the presence of electron-withdrawing groups placed at the aryl motif from the imine scaffold increased the antibacterial activity.…”

“…A representative example reported by Bhalla and coworkers describes the synthesis of a series of trans -4-(thiophenyl)pyrazolylyl β-lactams 1 . 34 The synthesis proceeds through a Staudinger cycloaddition reaction of (thiophenyl)pyrazol substituted Schiff's bases 2 and 2-substituted ethanoic acid or acid chloride derivatives 3 (Scheme 1a) in the presence of NEt 3 or POCl 3 /NEt 3 . The ketene intermediates are generated in situ through the deprotonation of carboxylic acid derivatives 1 (X = OH) by using NEt 3 , followed by the formation of an active ester with POCl 3 , which subsequently reacts with NEt 3 , or by direct reaction with NEt 3 if ethanoyl chloride derivatives 1 (X = Cl) are employed.…”

Designed synthetic pathway of stereoselective novel monocyclic cis‐bis‐β‐lactams including a 1,3,4‐thiadiazole‐2,5‐dithiol constituent: Antimicrobial activity, molecular docking

“…Various work has been done on the synthesis and modification of β-lactams to increase their antimicrobial activities. The most tremendous significance of the β-lactams nucleus in the field of medicinal chemistry is the various synthetic procedures that have been reported for forming the β-lactams [21][22][23][24][25][26][27]. The most commonly used synthetic procedure is [2 + 2] cycloaddition ketene-imine, that is, Staudinger reaction [28][29][30].…”