ABSTRACT
The dehydration of beta-hydroxy ketones and beta-hydroxy esters is a synthetically useful method for the conversion of these compounds to the corresponding alpha,beta-unsaturated derivatives. Cerium(III) chloride heptahydrate in combination with sodium iodide in refluxing acetonitrile acts as an efficient reagent for this conversion. The present procedure, which utilizes cheap and "friendly" reagents, offers the corresponding (E)-enones in good yields as the only isolable products.
ABSTRACT
The needles of Taxus wallichiana afforded a new analogue of taxinine M [1a] and two derivatives of brevifoliol [2a, 3a]. The conformation of 3a was investigated by nmr spectroscopy with the aid of variable-temperature experiments and in situ reactions.
Subject(s)
Paclitaxel/analogs & derivatives , Plant Leaves/chemistry , Plants, Medicinal/chemistry , Magnetic Resonance Spectroscopy , Molecular Conformation , Nepal , Paclitaxel/chemistry , Paclitaxel/isolation & purificationABSTRACT
Anti-10 deacetylbaccatin III (DAB) antibodies (IgY) were elicited in hens immunized with a succinyl-DAB/BSA conjugate and extracted from egg yolk. As shown by indirect competitive inhibition enzyme immunoassay (CIEIA), the addition of free-DAB competitively inhibited the binding of affinity purified anti-DAB IgY to DAB/BSA solid phase conjugated antigen. The assay enabled the detection of DAB in concentrations as low as 7.5ng/ml (13.7 nM DAB), whereas anti-DAB IgY did not react with taxol even at a concentration a thousand times higher. The structural requirements of the diterpenoid nucleus for binding to IgY were considered on the basis of the levels of cross-reaction found with 10 authentic taxanes. The results indicate that anti-DAB IgY represents the first high affinity antibody produced capable of recognizing the ring skeleton of taxol precursors.
