Diastereoselective functionalisation of benzo-annulated bicyclic sultams: Application for the synthesis of cis-2,4-diarylpyrrolidines.

The cis-dibromination of unsaturated bicyclic bridgehead sultams 5a and 5b, and experiments designed to understand the cis-stereochemical outcome of these reactions, are described. In the case of 5b, a novel solvent dependent carbocation rearrangement occurs with the formation of 18b. cis-Dibromides 13a and 13b undergo regioselective dehydrobromination, and the participation of the resultant vinyl bromide 24a in lithiation and Pd-coupling chemistry is described.

Enantiospecific synthesis of (+)-alstonisine via a stereospecific osmylation process.

The first enantiospecific total synthesis of (+)-alstonisine has been accomplished from D-tryptophan methyl ester 13 in 12% overall yield (in 17 reaction vessels). A diastereospecific osmylation process has been employed as a key step to convert indole 18 into spirocyclic oxindole 19. Mechanistic studies of the stereoselective osmylation of the 2,3-indole double bond of indole alkaloids has been carried out.

Quararibea Metabolites. 4.(1) Total Synthesis and Conformational Studies of (+/-)-Funebrine and (+/-)-Funebral.

Syntheses of racemic forms of the main secondary metabolites of Quararibea funebris, (+/-)-funebrine, (+/-)-funebral, and their biogenetic precursor (+/-)-(2S,3S,4R)-gamma-hydroxyalloisoluecine lactone have been developed. In synthetic studies, a new variation of the Paal-Knorr condensation employing titanium isopropoxide was utilized to construct the pyrrole lactone moiety. Two efficient synthetic approaches to the key (+/-)-gamma-amino lactone have been developed, one based on Claisen chemistry and the other on addition reactions to the butenolide ring of beta-angelicalactone.

Monitoring cholesterol autoxidation processes using multideuteriated cholesterol.

Deuterium-labeled cholesterol is used to monitor for artifactually produced cholesterol oxidation products during analysis. [2H9]Cholesterol, labeled on the side chain, is added to the sample immediately upon isolation, and the ratios of labeled to unlabeled oxides and of labeled to unlabeled cholesterol are monitored by capillary gas chromatography-mass spectrometry. The analytical methodology involves an initial solvent extraction followed by silica gel LC and reversed-phase HPLC to isolate and concentrate the oxide fraction.

Peripheral neuropathy profile in various groups of diabetics.

The results of applying a battery of peripheral nerve function tests in three groups of diabetics are reported. The tests examined the integrity of all the major subgroups of nerve fibres. The diabetics were grouped according to the clinical severity of their neuropathy: Group I--11 patients with long standing diabetes but clinically insignificant neuropathy, Group II--27 patients with mild neuropathy and Group III--23 patients with neuropathic foot lesions.