Uko E. Udodong

Total synthesis of (+)- and (−)-norsecurinine

Abstract (−)-Norsecurinine ( 1a ) has been prepared in a stereospecific fashion beginning with the acetylenic oxazole 18 . Diels-Alder cyclization of 18 afforded the furanoketone 19 , which was transformed in five steps to the butenolide mesylate 24 . Transannular alkylation of 24 then afforded 1a . In identical fashion, ent- 18 gave (+)-norsecurinine ( 1b ).

Total synthesis of (±)-paniculide-a

Abstract An efficient synthesis of the paniculide A precursor 4 has been achieved beginning with 3-methylglutaric anhydride, and utilizing as the key step an intramolecular Diels-Alder reaction of an acetylenic oxazole to give a 2-methoxyfuran. Acid hydrolysis then provided the requisite butenolide ring characteristic of the paniculides.

Bis heteroannulation. 8. Total synthesis of (±)-paniculide-A

Abstract An efficient synthesis of the title compound 1 has been achieved beginning with 3-methylglutaric anhydride.

Direct elaboration of pent-4-enyl glycosides into disaccharides

Pent-4-enyl glycosides, on treatment with halonium ions, become chemospecifically activated so that coupling with partially protected monosaccharides can be effected, leading to the in situ formation of disaccharides.