Lactams, Organic Syntheses procedures

Abstract The possible utilization of room temperature ionic liquids (RTILs), instead of volatile organic compounds (VOCs), in the electrochemical procedures of organic synthesis has been discussed. The synthesis of p-lactams, the activation of carbon dioxide and its utilization as renewable carbon source and the carbon-carbon bond formation reactions via umpolung of aldehydes (benzoin condensation and Stetter reaction) and via Henry reaction have been selected as typical electrochani-cal methodologies. The results, related to procedures performed in RTILs, have been compared with those performed in VOCs. The double role of RTILs, as green solvents and parents of electrogenerated reactive intermediates or catalysts, has been emphasized. 

Chapter 16 outlines the possible utihzation of room-temperature ionic liquids (RTILs), instead of volatile organic compounds (VOCs), in the electrochemical procedures of organic synthesis of alpha- and beta-lactams. The activation of carbon dioxide and its utilization as a renewable carbon source is also highlighted. 

The synthesis of the azetidin-2-one nucleus, via the classical annulation of acetyl-chlorides with imines, requires more than stoichiometric amounts of Uiethylamine (about 3 equivalent), which cannot be recovered and reused. In addition, the procedure needs a large amount of organic solvents (VOCs) and, as a consequence, causes a large amount of waste. To overcome these difficulties, the possible ytterbium (III) triflate-catalysed stereoselective synthesis of P-lactams via [2+2] cyclocondensation in ionic liquids has been investigated by Su et al. (Scheme 16.4) [93]. 

A short procedure for the synthesis of peptidomimetic y-amino acids was developed beginning with the synthesis of 5-benzyl-5-azabicyclo[2.2.1]hept-2-ene (57) from the cycloaddition of cyclopentadiene with iminium salts. Benzonitrile oxide converted (57) to regioisomeric cycloadducts (58a,b). The Ru02-catalysed oxidation of the latter by NaI04 in the presence of H20/AcOEt resulted in the formation of the corresponding A-benzoyl variants of (58a) and (58b) as the major products (35% and 33%), N-benzyl-lactams (17% and 15%), and the lactams (59a,b) in 13% and 12% yields. The quantitative hydrolysis of the lactams (59a,b) in THE by methanesulfonic acid and water resulted in the desired y-amino acids (60a,b), which were isolated as insoluble salts of methanesulfonic acid from the organic solution by simple filtration. ... 

A carbon analogue of penicillin V (Ic) was resistant to Bacillus cer-eus B l ctamase and moderately active against gram-positive organisms.6 ) Several 2-acetoxymethyl penicillins (2ja,y6 and 2-spirocyclopropyl cephalosporins (3 )65 vere prepared. Various chemical procedures were developed for the 7(6)a-methoxylation of B-lactam antibiotics.66-72 Conversion of penicillins to cephalosporins was achieved by new synthetic routes.73-76 Some [2,3]-fused tricyclic cephem derivatives (4a-c) were synthesized.77,78 Compound displayed significant antibiotic activity.78 Racemic cephalothin, 7-methoxycephalothin, and cefoxitin were obtained by total synthesis of a novel type.79-81 nuclear analogue of a 7-methylcephalosporin (5), prepared by total synthesis, lacked antibiotic activity,82... 

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