共查询到20条相似文献,搜索用时 15 毫秒
1.
2.
3.
4.
5.
6.
7.
8.
《Carbohydrate research》1986,147(2):247-264
l-(1-13C, 5-2H)Arabinose (6D) and l-(2-13C, 5-2H)arabinose (8D) have been synthesized by degradation of 2,3-O-isopropylidene-α-l-rhamnofuranose (2) to l-(4-2H)erythrose (5β,5αD), with subsequent chain elongation to 6D plus l-(1-13C, 5-2H)ribose (7D), the latter being converted into 8D. Intermediates were identified by complete assignment of the 13C chemical shifts employing carbon-carbon and carbon-deuterium coupling constants, deuteration shifts, differential isotope-shifts, and deuterium spectra. The anomeric carbon atoms of 2 and 2,3-O-isopropylidene-l-(1-2H) erythrose (4D) gave only single 13C resonances, suggesting that these two compounds exists in only one major anomeric configuration, clarifying previously reported work. The synthesis of 2,3-O-isopropylidene-l-(1-2H)rhmanitol (3D) facilitated the assignment of the signals in the 13C spectra of the nondeuterated analog. Specific deuterium-enrichment and the observed carbon-deuterium coupling (1JC,D ∼22 Hz) not only served to identify the deuterated carbon atom unambiguously in 3 but also permitted assignment of closely spaced resonances. The deuterium spectrum of 2,3-O-isopropylidene-l-(1-2H)erythrofuranose (4D) showed only a single resonance, indicating preponderance of one anomer, in accord with the observation of a single C-1 resonance in the 13C spectrum. 相似文献
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
Incorporation of 3H and 14C from (6 alpha-3H)penicillin N and (10-14C,6 alpha-3H) penicillin N into deacetoxycephalosporin C. 总被引:1,自引:1,他引:0 下载免费PDF全文
1. In a cell-free system prepared by lysis of protoplasts of Cephalosporium acremonium mutant M-0198, 3H and 14C were incorporated from singly- and doubly-labelled penicillin N into deacetoxycephalosporin C. 2. The deacetoxcephalosporin C obtained from the above feeding experiments was converted into two different crystalline derivatives, namely N-phthalimidodeacetoxycephalosporin C bisbenzhydryl ester and N-phthalimidodeacetoxycephalosporin C bisdicyclohexylamine salt and recrystallized to constant specific activity or constant ratio of specific activity. 3. That 3H is incorporated at C-7 in the biosynthesized deacetoxycephalosporin C was shown by the loss of radioactivity (95.2%) after methoxylating the derived N-phthalimidodeacetoxycephalosporin C bisbenzyhydryl ester. 4. Deacetoxycephalosporin C was also the product of the cell-free reaction conducted in the presence of ferrous ions and ascorbic acid, as shown by two-dimensional paper electrophoresis-chromatography; these additives appreciably improved the efficiency of conversion. 相似文献
19.
20.