Azetidinone system

The mild conditions of the base-catalyzed sulfonate synthesis are particularly apparent in the case of two reactions in which the reacting OH groups are present in an azetidinone system 155... 

Alkenyl-2-azetidinone systems could be converted to bicyclic (3-lactam carboxylic esters and hence carboxylic acids (Fig. 5) via tandem Ireland-Claisen rearrangement and subsequent alkene metathesis [250],... 

A similar intramolecular nucleophilic capture of an allylic sulfenate generated thermally from the corresponding sulfoxide was also reported for the facile transformation of the azetidinone 61 into a new 3-acetylthio-2-thiacephem ring system 62 (equation 29)127. 

Cationic Fp (olefin) complexes [Fp = f/5-C5H5Fe(CO)2] undergo regio-specific addition of heteroatomic nucleophiles.32 Subsequent ligand transfer (carbonyl insertion) occurs with retention of configuration at the migrating center (R—Fe—CO -> RCOFe).33 A combination of these processes has provided a novel stereospecific azetidinone synthesis which can also be applied to condensed systems.34... 

A rather complex reactivity towards the cyclopropenone system is exhibited by N-nucleophiles. Thus, ammonia reacts with diphenyl cyclopropenone to yield either the enamino aldehyde 323222> or a mixture of the cis and trans isomeric diphenyl azetidinones 522223 depending on the reaction conditions these products result from primary addition of the nucleophile at C,(2 ... 

The combination of the electrogenerated chloro cation [Cl] with diphenyldise-lenide is a typical example of the functionalization of an olefin. The electrochemical oxyselenation-deselenation of (1) to (2) proceeds in an MeOH-NaCl-(Pt) system (Scheme 1) [32]. The bromide salt-promoted oxyselenation of olefins is discussed in Sect. 15.2.2. Penicillin (3) can be converted into the oxazoline-azetidinone (4) by a chloride salt-promoted paired reaction in an MeOH-t-BuOH(5 l)-MgCl2-(Pt) system at —40°C in 74 93% yield (Scheme 2) [33, 34]. This conversion probably involves an initial attack of an... 

Lactams are named in several ways. They are named as alkanolactams by the IUPAC substitutive system, such as 3-propanolactam, 4-butanolactam, 5-pentanolactam, and 6-hexano-lactam, respectively, for the 4-, 5-, 6-, and 7-membered rings, respectively. An alternate IUPAC method, the specialist heterocyclic nomenclature system, names these lactams as 2-azetidinone, 2-pyrrolidinone, 2-piperidinone, and hexahydro-2f/-azepi n-2-one, respectively. These lactams are also known by the trivial names fl-propiolactam, a-pyrrolidone (y-butyrolactam), a-piperidone (8-valerolactam), and e-caprolactam, respectively. 

Takasago group and Nozaki reported the synthesis of the 1-methylcarbapenem intermediate 78 by hydroformylation of the 4-vinyl / -lactam, (3BINAPHOS system followed by oxidation (Scheme 8, Table 13, entry Slightly better selectivities are... 

The nomenclature used in this section differs from the strictly systematic rules used by Chemical Abstracts to index fused-ring azetidinones, but conforms more to that commonly found in the literature describing the /3-lactam antibiotics. A description of this naming system is given in the introduction (Section 5.12.1). Virtually all of the compounds discussed in this section contain a carboxyl group adjacent to the /3-lactam ring and conform to general structure (49). 

X-ray crystallographic examination of bicyclic azetidinone (106) indicates that the azetidinone ring is essentially planar (73JA4647). Selected bond angles and distances are listed in Table 7. H NMR and IR properties for several bicyclic azetidinones are given in Table 8. Theoretical calculation (79T1499) and CD studies (78JOC4438) for the 1-azabicyclo[3.2.0]heptane system have been reported. 

In addition, there are many important nonantibiotic uses of 2-azetidinones in fields ranging from enzyme inhibition [15-21] to gene activation [22], Systems containing one carbon atom common to two rings, spirocyclic compounds, represent an important structural organization. Spirocyclic p-lactams (Fig. 3) behave as p-tum mimetics [23-26] as well as enzyme inhibitors [27, 28], they are precursors of a,a-disubstituted p-amino acids [29-32], and the spiranic p-lactam moiety is present in chartellines and chartelamides [33-38], a family of marine natural products. Synthetic studies and biosynthetic speculation inspired by an unexpected reaction on the marine alkaloid chartelline C have been described [38],... 

The reductive opening of epoxy-p-lactam 97 with titanocene(III) chloride gives rise to a benzyl radical that can be trapped by intramolecular n systems to give the tricyclic 2-azetidinone 98 (Scheme 32) [78]. 

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