摘要:

Oxidation with permanganate of caerulomycin A labeled biosynthetically from [U-14C]lysine in cultures ofStreptomycescaeruleusyielded picolinic acid with the same specific activity as the antibiotic. [3H]Picolinic acid was incorporated into caerulomycin A with high efficiency and the label was also found exclusively in picolinic acid after oxidation, implicating free picolinic acid as an intermediate in the pathway from lysine. The substituted pyridyl ring of caerulomycin was labeled by [2-13C, 1,3-14C]glycerol.13C nuclear magnetic resonance analysis located the13C predominantly at C-6, suggesting that C-5, C-6, and C-7 were derived from glycerol as an intact three-carbon precursor. Since no incorporation of [1-13C]glyceric acid was detected and [3-13C, 3-14C]methylglyoxal labeled the antibiotic only marginally, these compounds are probably not biosynthetic intermediates en route from glycerol. A new caerulomycin possessing an aldehyde in place of the aldoxime substituent at C-6 was isolated from culture broths and is postulated to be a late intermediate in the formation of caerulomycin A.

ISSN:0008-4042    

DOI:10.1139/v88-031

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

The syntheses of 2,5-anhydro-1,6-di-C-amino-1,6-dideoxy-3,4-di-O-methyl-D-mannitol11and itsN,N′-dimethyl analogue15are described, as are couplings to bis-tartaro-18-crown-61to give a macrobicyclic cryptand16, and macrocycles17and18bearing four lateral groups, which are potential precursors of a cylindrical stacked macrocyclic system such as6.

ISSN:0008-4042    

DOI:10.1139/v88-032

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

Insituinfrared spectroelectrochemistry has been used to observe electrolyte/solvent breakdown processes in TBAF/acetonitrile at a platinum electrode. Anodic breakdown gives the adduct CH3CNBF3as the major product. Cathodic breakdown gives the anion of 3-aminocrotonitrile as the major product in the absence of water, and the formation of this product is a consequence of reduction of hydrogen dissolved in the metal. In the presence of water the anion of acetamide is also formed, and breakdown commences at much less negative potentials.

ISSN:0008-4042    

DOI:10.1139/v88-033

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

not available

ISSN:0008-4042    

DOI:10.1139/v88-034

出版商:NRC Research Press    

年代:1988

数据来源: NRC