C-3 β-lactam carbocation equivalents: versatile synthons for C-3 substituted β-lactams

A New Synthetic Approach to Novel Spiro‐β‐lactams

“…[24,27] Furthermore, the trans-3-benzylthio-3-chloroazetidin-2-ones 2a-e, the appropriate β-lactam carbocation equivalents, were obtained by stereospecific chlorination of 1a-e by treatment with Nchlorosuccinimide (NCS) in the presence of catalytic amounts of AIBN by the reported procedure. [24][25] On treatment [25,27] with propargyl alcohol or allyl alcohol in the presence of ZnCl 2 /SiO 2 in chloroform at reflux, these β-lactam carbocation equivalents 2a-e afforded the cis-3-benzylthio-3-(prop-2-ynyloxy/-enyloxy)azetidin-2-ones 3a-e and 4a-b, considered potentially capable of undergoing halogen-mediated intrasulfenyl cyclization reactions (Scheme 1, Table 1). Table 1.…”

“…General: Compounds 1a-e, 2a-e, [24] 3a-e and 4a-b [25] were prepared as described previously. Spectroscopic data for compounds 1a-b and 2a-b [24] were reported previously.…”

“…Spectroscopic data for compounds 1a-b and 2a-b [24] were reported previously. NMR spectra were recorded on Jeol 300 and Bruker Avance II 400 spectrometers.…”

Synthesis of novel spiro-β-lactams

“…Synthesis of spiro-β-lactams 9a-e and 10a-e. using reported procedure. 11,12 These were transformed into their 3-chloro derivatives using SO 2 Cl 2 as chlorinating agent. 12,13 The conversion of 3-benzylthio-β-lactams into 3-chloro-3-benzylthio-β-lactams (4) was done with NCS in the presence of AIBN.…”

Synthesis of Novel Pyrazolylmethylene-Pyrimidine Heterocycles: Potential Synthons for Hybrid Β-Lactams

“…In our earlier studies, we have demonstrated the synthesis of selenoalkanoic acids useful as β-lactam precursors [31,32], novel 3-thio/seleno β-lactams and Lewis acid mediated functionalization [33][34][35][36][37][38][39], stereoselective cis-and trans-3-alkoxy-β-lactams [40], spirocyclic β-lactams [35,[41][42], (Z)-and (E)-3-allylidene-β-lactams [43], 3-keto-β-lactams [44] and bicyclic-β-lactams [45]. Recently, hybrid β-lactams I, II, III (Figure 1) with varied heterocyclic moieties have been shown to exhibit antimicrobial, antiprotozoal, anti-inflammatory and analgesic activities [46][47][48].…”