Preparation of 6α-monosubstituted and 6,6-disubstituted penicillanates from 6-diazopenicillanates: reactions of 6-diazopenicillanates with alcohols, thiols, phenylseleninyl compounds, and allylic sulphides, and their analogues

Acyclic Twisted Amides

“…In general, the amide bond geometry of structurally characterized β-lactams presented in Figures and − can be characterized as N-pyramidalized (average χ N of 54.4°), while twist is less significant (average τ of 19.2°), as expected from the geometry of the fused four-membered ring system. There is only a very scattered correlation between N-pyramidalization and twist of the amide bond, with the general trend of higher twist with increased nitrogen pyramidalization ( R 2 = 0.30).…”

“…The most common are [ 2 .4.0] and [ 2 .3.0] ring systems with the six-membered ring such as 1,3-oxazinane (e.g., 4.30 ), and more common five-membered ring, such as thiazolidine 1,1-dioxide (e.g., 4.32 ), thiazolidine 1-oxide (e.g., 4.33 ), thiazolidine (e.g., 4.34 ), 1,3-selenazolidine (e.g., 4.36 ), pyrrolidine (e.g., 4.81 ), imidazolidine (e.g., 4.94 ), or oxazolidine (e.g., 4.101 ) . In general, more dense substitution of the fused ring, in particular at the α-positions to the nitrogen atom and the carbonyl group and ring unsaturation, result in higher N-pyramidalization. − These N-pyramidalized amides are well-known to be highly reactive as acylating reagents and are important pharmacophores in medicinal chemistry research.…”

Synthesis and characterization of novel trans-3-benzyl/(diphenyl)methyl/naphthyl seleno substituted monocyclic β-lactams: X-ray structure of trans-1-(4′-methoxyphenyl)-3-(diphenyl)methylseleno-4-(4′-methoxyphenyl)azetidin-2-one

“…Pioneering research contributions in synthesis of bicyclic seleno-b-lactams such as selenapenems and selenacephames have been made by Perrone et al [11], Thomas et al [12], Fujita et al [13], Hakimelahi et al [14] and Gallagher et al [15,16]. In addition, Ohshiro et al [17], Liebscher et al [18], Torchiarolo et al [19] and Turos et al [20] have developed different strategies for the synthesis of monocyclic seleno-b-lactams.…”

Preparation and properties of substituted 6β-vinylpenicillanic acids

“…The route to compounds (3) and (4) involved initial nitrosation of the trichloroethyl ester of penicillin V (8) with dinitrogen tetroxide, followed by heating it, either in dichloromethane containing pyridine,' or, in better yield, without the pyridine, to give the 6-diazo-derivative (9). Using the method of Giddings et the diazo-ester (9) could be treated with either substituted allylic sulphides or selenides.…”

“…The route to compounds (3) and (4) involved initial nitrosation of the trichloroethyl ester of penicillin V (8) with dinitrogen tetroxide, followed by heating it, either in dichloromethane containing pyridine,' or, in better yield, without the pyridine, to give the 6-diazo-derivative (9). Using the method of Giddings et the diazo-ester (9) could be treated with either substituted allylic sulphides or selenides. The allylidenes (1 5 ) and (1 6) were more readily prepared from the corresponding selenides (10) chloroperbenzoic acid at -5 "C followed by ready elimination of benzeneselenenic acid at room temperature.…”