Free fatty acids from the crude hexane extract of the aerial parts of Heliotropium indicum Linn. Growing in Phitsanulok, Thailand

Sixteen free fatty acids from the crude hexane extract of the aerial parts of Heliotropium indicum Linn. growing in Phitsanulok, Thailand, have been identified after conversion to their methyl esters with boron trifluoride-methanol followed by quantification by GC-FID and identification by GC-MS analysis. They accounted for 95% of the chromatographable components, with 9,12-octadecadienoic acid, (39.7%), 9-octadecenoic acid (32.4%), hexadecanoic acid (14.2%) and octadecanoic acid (5.1%), as the major constituents. A small amount of 6,10,14-trimethyl-2-pentadecanone and 3,7,11,15-tetramethyl-2-hexadecen-1-ol as well as a homologous series of n-alkanes present at trace level and ranging from C25 to C31 was also found (see Table 1). The crude hexane extract has been shown to have modest antituberculosis activity (MIC of 100 mg/mL) against Mycobacterium tuberculosis H37Ra

Synthesis of castanospermine

The diastereoselective synthesis of castanospermine is described in 11 synthetic steps from L-xylose. The borono-Mannich reaction between L-xylose, allylamine and (E)-styrene boronic acid gives a tetrahydroxy amine with the desired configurations for C-6, C-7, C-8 and C-8a in the target molecule. A novel pyrrolo[1,2-c]oxazol-3-one precursor was employed to allow for the control of pi-facial diastereoselectivity in an osmium(VIII)-catalysed syn-dihydroxylation (DH) reaction. A regioselective ring-opening of the cyclic sulfate derivative of the resulting diol then secured the C-1 hydroxyl group of castanospermine with the correct configuration. A Mitsunobu cyclization then provided di-O-benzyl castanospermine and ultimately the final target alkaloid

Asymmetric synthesis of polyfunctionalized pyrrolidines and related alkaloids

This account describes our recent studies on the development of a general method of preparing polyfunctionalized pyrrolidine, indolizidine, pyrrolizidine and pyrrolo[1,2-a]azepines and their related alkaloids