Causes of variability in concentrations and diastereomer
patterns of hexabromocyclododecanes in indoor dust.
Of all the forms, the studies of its threo diastereomer
revealed that d-threo isomer has been found to be more active and also showed significant metabolic difference than l-threo enantiomer.
Since this reaction introduces two chiral carbons into the product, the cis alkenes are known to form a racemic mixture, and the trans isomer forms a stereospecific meso diastereomer
Moreover, during the oxidative work-up procedure in basic conditions the lactone ring may open and, together with the following relactonization, there is a risk of racemization of (1S, 5R, 6R)4a (the enantiopurity of the other diastereomer
(1S, 5R, 6S)-4a is not affected).
11) The noteworthy features of the synthesis are: the hydroxyl and the carboxylic acid functions in the reactants do not require protection-deprotection chemistry; the C-C bond formation step provides useful syn-selectivity giving the desired diastereomer
This past summer we worked on the synthesis of one diastereomer
of this peptidomimetic.
PSA expression increased in response to all four TBECH diastereomer
combinations in a dose-dependent manner.
In the so-called SS diastereomer
, the dioxolane ring lies perpendicularly to the channel axis.
was independently reacted with a second alkenyl anion which lead to the isolation of the same polycyclic compound after the cascade reaction took place.
The enantiomeric fractions (EFs) reported here are corrected using the responses of the isotopically labeled diastereomer
standards as described elsewhere (Marvin et al.
The second step (Equation 3) could then be carried out without purification leading to a single diastereomer
These levis are consistent with the ratios of HBCD found in a harbor porpoise and cormorant, where only [alpha]-HBCD was detected, [gamma]-HBCD is the prominent diastereomer
in sediment, whereas [alpha]-HBCD is consistently the highest in biota, and [beta]-HBCD always appears to be a very minor component.