Alkaloids amino acids

The [3+2] cycloaddition strategy provides an effective method to access valuable intermediates for the construction of biologically important alkaloids, amino acids, amino carbohydrates and P-lactams [58-62]. The reaction involves the concerted pericyclic addition of a dipole and a dipolarophile and considerable efforts have been made to render these reactions asymmetric nsing Lewis acid catalysis and chiral anxiliaries [63]. 

Alkaloid Amino acids in peptide moiety Degradation products Peak detectable by GLC ) (min) Ret. index MH+ (CI-MS)... 

This method is already relatively old and has been used for the past several years in organic chemistry and biochemistry. High kinetic energy (several keV) primary ions, e.g., Ar, bombard a surface on which the sample has been deposited. Under these conditions, ions are extracted from the surface and can be analyzed, Benninghoven and co-workers [102] presented a number of examples carbohydrates, alkaloids, amino acids (and derivatives) and peptides. As with the other methods, both positive and negative ionization modes are possible (Fig. 14). More recently, the same author [103] demonstrated the possibility of studying non-volatile nucleic acids and compared the results obtained with the other desorption methods. Sensitivity limits are on the order of ng. 

Accordingly, the design of the catalyst for asymmetric cyanation has mainly been performed using natural alkaloids, amino acid derived compounds with a basic moiety in the substituent, and Lewis acidic organometaUics modified with optically active compounds [11]. 

Almost all the syntheses require a natural product or a derivative of one. These are drawn from a chiral pool of alkaloids, amino acids, hydroxy acids, sugars, terpenes, and others. Typical alkaloids include ephedrine, cinchonidine, quinidine, and sparteine (10.5). 

In spite of the importance of chiral amino alcohol units for the synthesis of biologically important alkaloids, amino acids, b-lactams, and amino sugars, etc. 

Dipolar cycloadditions between nitrones and alkenes are most useful and convenient for the preparation of isoxazolidine derivatives, which are readily converted to 1,3-amino alcohol equivalents under mild reducing conditions (Tufariello 1984, Torssell 1988). In spite of the importance of chiral amino alcohol units for the synthesis of biologically important alkaloids, amino acids, 3-lactams, and amino sugars, etc. (for a review see Frederickson 1997), catalytic enantioselective 1,3-dipolar cycloadditions remain relatively unexplored (Seerden et al. 1994, 1995, Gothelf and Jorgensen 1994, Gothelf et al. 1996, Hori et al. 1996, Seebach et al. 1996, Jensen et al. 1997). Catalytic enantioselective... 

Because of the multitude of nicotine-related alkaloids, amino acids, and proteins in tobacco, diligent research eventually led to the identification of a host of alkyl amines in tobacco and smoke. In addition to ammonia, the only alkylamine listed as a tobacco smoke component in 1954 by Kosak (2170) was methylamine, but he questioned its identification even though he cited the 1904 report by Thoms (3912) and the 1930 report by Koperina (2161) on its identification. 

Hundreds of applications have been mentioned in the Zweig (1968) review acids, alkaloids, amino acids, antibiotics, antioxidants, food and feed additives, bases and amines, bile acids, carbonyls, dyes, enzymes, lipids, hydrocarbons, hormones, indoles, natural products, peptides, proteins, pesticides, plant growth regulators, pharmaceutical products, phenols, pigments (chlorophylls, xanthophylls, porphyrins, melanin, pterins, pteridines, anthocyanins, ilavonoids, etc.), polymers, purine and pyrimidine derivatives, quinones, RNA, DNA, organic sulfur compounds, steroids, sugars, toxins, vitamins, inorganic ions, and others. 

Alkaloids, amino acid derivatives, analgesics, antibiotics, benzodiazepines, carboxylic acids, carotenoids, pesticides, phenols, preservatives, steroids... 

Aliphatic and aromatic amines, alkaloids, amino acids, amino sugars, carboxyhc and sulfanihc acids, indole derivatives, nucleobases, nucleosides, nucleotides, peptides, dipeptides, polypeptides, phenols, phenothiazine bases, steroids, sulfonamides, water-soluble food dyes... 

Aliphatic and Related Natural Product Chemistry The Alkaloids Amino-acids, Peptides, and Proteins Biosynthesis Carbohydrate Chemistry Catalysis... 

Roots Flavonoids, phytosterol, alkaloids, amino acids, tannins, glycoside, and fatty acids [45]... 

Amines, Alkaloids, Amino Acids, Peptides, and Nucleic Acids... 

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