Sugar lactams

Sugar lactams from azidoaldonic acid lactones <-... 

Aldehydes can be converted into amides by a Schmidt rearrangement (see Schmidt reaction, under Section 9.3.2.2). This reaction is particularly interesting for the formation of sugar lactams [187]. When aldehydes are treated with a-azido alcohols in the presence of acid, the rearrangement yields cyclic imidates [188]. Nitriles can be obtained directly in high yields by reacting aldehydes with triazidochlorosilane [189]. 

Lactam (Section 20 15) A cyclic amide Lactone (Section 19 15) A cyclic ester Lactose (Section 25 14) Milk sugar a disacchande formed by a p glycosidic linkage between C 4 of glucose and C 1 of galactose... 

Stereocontrolled synthesis of oxabicyclic (3-lactam antibiotics via [2- -2] cycloaddition of isocyanates to sugar vinyl ethers 96CC2689. 

Many peptide antibiotics have novel structural motifs, such as cyclic structures and are often further modified, (such as in jS-lactamic antibiotics) and conjugated with sugars, lipids, and other molecules. 

Recent research deals with stereoselective 1,3-dipolar cycloadditions of nitrones for the syntheses of alkaloids and aza heterocycles asymmetric synthesis of biologically active compounds such as glycosidase inhibitors, sugar mimetics, /3-lactams, and amino acids synthesis of peptido-mimetics and peptides chemistry of spirocyclopropane heterocycles synthesis of organic materials for molecular recognition and photochemical applications. 

Synthesis of p-lactam antibiotics from sugars (either as chiral auxiliary or chiron), describing the general methodology developed in 1990s by Chmielewski and based on [2 + 2] cycloaddition of isothiocyanides to sugar olefins, was also comprehensively reviewed.5... 

The UV 242, 291, 320, 334, 354, and 370 nm) and IR 1670 and 3400 cm ) spectra of 4 -N-methyl-5 -hydroxystaurosporine (300) were very similar to those of (+)-staurosporine (295) (see Scheme 2.74), indicating the presence of a similar indolo[2,3-fl]carbazole framework with a lactam function. The NMR spectra of 4 -N-methyl-5 -hydroxystaurosporine (300) were also very similar to those of (+)-staurosporine (295) (see Scheme 2.74), except for the difference in the substitution pattern of the sugar moiety. Thus, the H-NMR spectrum showed two shielded N-methyl singlets at 2.37 and a doublet (/=9.9Hz) for the C-5 proton at 4.43 and the C-3 singlet at 5 3.95, and a shielded doublet (/=9.9 Hz) for the C-4 proton at 5 3.02, indicating the presence of additional methyl and hydroxy groups at the C-4 N-methyl and the C-5 carbon, respectively. Based on these spectral data, and the structural similarity to (+)-staurosporine (295), the structure 300 was assigned to 4 -N-methyl-5 -hydroxystaurosporine. This structure was further supported by the C-NMR and NOESY spectra (298) (Scheme 2.75). 

The UV spectrum [7max 238, 256 (sh), 293 (sh), 314, 362 (sh), and 390 (sh) nm] of rebeccamycin (337) indicated the presence of an indolo[2,3-fl]pyrrolo[3,4-c]carbazole-5,7(6H)-dione framework. This was also discernible from its IR spectrum. The H-NMR spectrum indicated the presence of an amide NH at 8 11.37 and an indole NH at 6 10.30, in addition to signals for aromatic protons and a sugar moiety. Unlike (+)-staurosporine (295) (see Scheme 2.74), where the lactam function deshielded only the ortho C-4 proton, the C-4 and C-8 aromatic protons in rebeccamycin are both deshielded due to the anisotropic deshielding effect of the phthalimide function. 

The chiral lactone (178) has been used for the synthesis of a variety of natural products, such as sugars, lignans, terpenes, alkaloids, and P-lactams as a chiral building block 182c,184). The use of (178) as a powerful inductor of asymmetry was mainly established by Takano et al. 181, 84> one can expect more highly interesting reports from this group. 

Beet molasses - [SUGAR - BEET SUGAR] (Vol 23) -use in antibiotic fermentation [ANTIBIOTICS - BETA-LACTAMS - CEPHALOSPORINS] (Vol 3)... 

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