A general method for the synthesis of phthalaldehydic acids and phthalides, many of which are key intermediates in natural product synthesis, has been developed. o-Bromobenzaldehydes la-f were first protected in situ as -morpholinoalkoxides by reaction with lithium morpholide. Treatment of the -morpholinoalkoxides 3a-f with n-butyllithium (to exchange bromine with lithium) followed by sequential treatment with solid C02 and dilute acid afforded the phthalaldehydic acids 6a-f, respectively. Reduction of 6a-f with NaBH4 in EtOH furnished the phthalides 7a-f, respectively, in nearly quantitative yields. Efficient methods for the synthesis of the o-bromobenzaldehydes la-d, which were not readily available, are also described.
In vitro metabolic stability assays are used to screen compounds for stability in the presence of various drug metabolizing enzymes, usually cytochrome P450 in liver preparations (e.g., liver microsomes). High-throughput metabolic stability assays using pooling methods have been developed to keep pace with screening requirements at the lead ADME optimization stage. In our laboratory, we have improved the metabolic stability assay using the cassette analysis method, column switching, and incorporated time saving techniques in method development to yield a robust method which reduces data turnaround time, increases compound throughput, and maximizes mass spectrometer usage. This method can determine metabolic stability using microsomes or hepatocytes from any species. We describe our findings following incubation of 40 different compounds with human liver microsomes and analysis by the cassette and discrete analysis methods. Similar metabolic stability results were obtained using the cassette analysis and discrete analysis method. An overall 70% time savings was achieved by pooling four new compounds into one sample for method development/MS optimization, cassetting four samples into one sample to minimize the number of injections on LC/MS/MS analysis, and using a column switching system to analyze the samples, which results in a two-fold decrease in the LC/MS/MS analysis time.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.