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4-Unsubstituted P-lactam

Lactams. This N-(cyanomethyl)amine reacts with lithium ester enolates to afford 4-unsubstituted p-lactams in 60-75% yield (equation I). This reaction is generally applicable to N-(cyanomethyl)amines. 3-Amino-p-lactams can be ob-... [Pg.29]

The synthesis of ot-branched 3-amino-4-unsubstituted p-lactams (IV, Fig. 3) could be performed efficiently via an asymmetric alkylation of a single 3-oxazoli-dinyl azetidin-2-one [248]. [Pg.161]

Staudinger reactions have been used to obtain P-lactams as substituents on quinones (e.g. 55) <01TL1503> and as spiro compounds (e.g. 56) <001JC(B)304>. The MA -dialkyl-hydrazone 57 was used to obtain 58, which was A -deprotected in high yield with magnesium monoperoxyphthalate in methanol to give the 1,4-unsubstituted P-lactam <00AG(E)2893>. [Pg.82]

In a series of papers [54-56], Palomo reported work leading to C-4-unsubstituted P-lactams including 3-aminonocardicinic acid. The cis. trans ratio of products of the ketene-imine cycloaddition was shown to be dependent on the bulk of the substituents in these groups. Thus while imine 78 gave an equimolar ratio of cis and trans azetidinones 79, use of the 2-methylcinnamaldehyde-derived imine 80 afforded only the c/5-compound 81. A useful method was... [Pg.547]

Acetyl chloride has been used as a ketene precursor to prepare P lactams unsubstituted at C3. Unsubstituted imine fragments pose special difficulties in the Staudinger reaction. Formaldehyde imines are difficult to prepare and handle, and generally p-lactams unsubstituted at C4 are not readily accessible. By contrast, formaldehyde hydrazones are more stable and can be used in place of the unstable imines in the Staudinger reaction to afford 4-unsubstituted P-lactams. ... [Pg.60]

Gallop et al. [80] reported the preparation of p-lactams via a [2+2] cycloaddition reaction of ketenes with resin-bound imines derived from amino acids (Scheme 9). This is another solid-phase adaptation of the Staudinger reaction, which could lead to the synthesis of structurally diverse 3,4-bis-substituted 2-azetidinones [81]. In addition, a novel approach to the synthesis of A-unsubstituted-p-lactams, important building blocks for the preparation of p-lactam antibiotics, and useful precursors of chiral p-amino acids was described [82]. [Pg.269]

In 2001,3-unsubstituted 4-aUcyl-4-carboxy-2-azetidmones have been reported to be prepared by base-assisted intramolecular alkylation of A/-benzyl-A/-chloroacetyl amino acid derivatives [180]. A/-benzyl or A/-(p-methoxybenzyl) amino acid derivatives in THF, treated with propylene oxide and chloroacetyl chloride afforded the A/-chloroacetyl amino acid derivatives. The treatment of the latter in CH3CN with CS2CO3 (or NaH) produced the intramolecular cyclization of 4,4-disubstimted p-lactams, (Scheme 81). [Pg.146]

One facile entry to intermediates possessing the y-lycorane skeleton involved the alkoxide-catalyzed cyclization of the isocarbostyril 34b, which was readily accessible by the N-alkylation of 34a, to provide the y-lycorane derivative 35 (104). The amino derivative 36 was available in three steps from the isocarbostyril 37 by a similar sequence of reactions, but several attempts to prepare the p-unsubstituted enone lactam 38 by this approach resulted in the loss of the N-(4-oxobutyl) appendage by a retro-Michael reaction and were unsuccessful. [Pg.266]

In 2003, Cainelli and coworkers have shown that monocyclic p-lactams substituted at the C-3, the C-4, and the N-1 positions are the most active in inhibiting LE and gelatinases MMP-2 and MMP-9 [340]. They have also reported that C-4 unsaturation on the p-lactam ring raised the inhibitory activity towards these proteases, with selectivity over LE by 3-[l-(ferf-butyldimethylsilyloxy)ethyl] derivatives, and over the gelatinase MMP-2 by C-3-unsubstituted 4-[l-ethoxycarbonyl]... [Pg.184]

Brickner [69, 70] reported a useful extension of this methodology in which primary 2-bromoallylamines undergo the cyclization reaction providing direct access to AT-1-unsubstituted a-alkylidene-p-lactams. Significant modifications of the reaction conditions included the use of Pd(Ph3P)4 rather than Pd(OAc)2 and dimethylformamide as the solvent as opposed to the toxic hexamethyl-phos-phoramide employed in the earlier work. Allylic siloxy substituents were... [Pg.553]

Racemic 4-acetoxy-3-unsubstituted azetidinone 10 and homochiral (3R,4R)-3-(IR)-hydroxyethyl derivative 11, commercially available intermediates industrially prepared by the so-called CSI route , testify to the importance of this ring formation strategy. By using vinyl acetate as the olefin partner in the chlorosulfonylisocyanate-alkene cycloaddition, in 1974, Clauss et al. [10] laid down the basis of this approach in the field of p-lactam antibiotics. The most recent efforts have been directed to the key intermediate 11 and its synthetic equivalents 12, 13. Starting from methyl 3R-hydroxybutyrate [11], three independent methodologies have been realized, the main difference being the type (ether, thioether, ester) of enolate used. [Pg.617]

The synthesis of p-lactams unsubstituted on nitrogen also cannot be accomplished directly due to the instability of most imines derived from ammonia. However, imines derived from 4-methoxyaniline and 4-ethoxyaniline readily afford A/-aryl p-lactams cleavage of the A-aryl bond is accomplished by oxidation with ceric ammonium nitrate. A-Trimethylsilyl imines have also been used to provide NH P-lactams. ... [Pg.60]


See other pages where 4-Unsubstituted P-lactam is mentioned: [Pg.29]    [Pg.575]    [Pg.29]    [Pg.575]    [Pg.70]    [Pg.77]    [Pg.352]    [Pg.80]    [Pg.552]    [Pg.56]    [Pg.61]    [Pg.65]    [Pg.252]    [Pg.265]    [Pg.252]    [Pg.265]    [Pg.252]    [Pg.265]    [Pg.666]    [Pg.252]    [Pg.265]    [Pg.65]    [Pg.939]    [Pg.577]    [Pg.631]    [Pg.103]   
See also in sourсe #XX -- [ Pg.12 , Pg.162 ]




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Unsubstituted lactam

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