Vitamin B is a natural and environmentally friendly catalyst. When exposed to light or heat, central Co(i) can react with electrophiles to obtain alkyl radicals, which can subsequently be used in complex processes. Herein, the vitamin B-catalyzed coupling reaction of nitroalkanes and diazo compounds is reported leading to substituted tertiary nitroalkanes in moderate yields. The reaction conditions were optimized, and the scope and limitations of the reaction were also investigated.
Download full-text PDF |
Source |
---|---|
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC11394470 | PMC |
http://dx.doi.org/10.1039/d4ra05084c | DOI Listing |
J Org Chem
June 2001
Departamento de Química Orgánica e Inorgánica, Facultad de Química, Universidad de Oviedo, 33071-Oviedo, Spain.
A comparative study of alkoxycarbonylation processes of both 19-nor-A-ring and A-ring stereoisomers of 1alpha,25-dihydroxyvitamin D3 analogues catalyzed by Candida antarctica lipase B (CAL-B) has been described. The presence of the methyl group in the A-ring at C-2, as in 3-6, has a determining role in the regioselectivity of the biocatalysis, mainly allowing the hydroxyl group at C-5 position to react. For the 19-nor-A-ring stereoisomers 7-10, which lack the C-2 methyl group, the configurations at C-3 and C-5 have a high influence in the selectivity exhibited by CAL-B.
View Article and Find Full Text PDF5-Pyridoxic-acid oxygenase, a cytoplasmic enzyme formed when Arthrobacter Cr-7 is grown with pyridoxine as a sole source of carbon and nitrogen, was purified about 190-fold to homogeneity from fully induced cells. The enzyme catalyzes Reaction a, (Formula: see text) the essential ring-opening step in the degradation of pyridoxine, and provides a second example of an FAD-dependent oxygenase that adds both two hydrogen and two oxygen atoms to its substrate. 5-Pyridoxic-acid oxygenase has an isoelectric point of 4.
View Article and Find Full Text PDFEscherichia coli can synthesize alpha-ketoisovalerate, the precursor of valine, leucine, and pantothenate, by three routes: anabolically via dihydroxyacid dehydrase and catabolically via both the branched-chain amino acid transaminase (transaminase B) and the alanine-valine transaminase (transaminase C). An E. coli K-12 mutant devoid of transaminase C (avtA) was isolated by mutagenizing an isoleucine-requiring strain devoid of transaminase B (ilvE::Tn5) with Mu d1(Ap lac) and selecting for valine-requiring derivatives which were ampicillin resistant, Lac+, able to crossfeed an ilvD mutant, and unable to grow on alpha-ketoisovalerate in place of valine.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!