Herman Steven Overkleeft

A facile transformation of sugar lactones to azasugars

Abstract The synthesis of pyrano- and furano- sugar lactams from the corresponding lactones, in a five step sequence, is described.

A formal synthesis of castanospermine using an olefin metathesis cyclisation reaction as a key step

Abstract The formal synthesis of castanospermine (1) starting from tetrabenzylgluconolactam (3) is described. Olefin metathesis cyclisation reaction of dialkene 9, derived from 3, leads to indolizidinone 10, which can be used as a key intermediate for the synthesis of castanospermine (1) and its analogues.

SYNTHESIS MEDIATED BY RING-CLOSING METATHESIS : APPLICATIONS IN THE SYNTHESIS OF AZASUGARS AND ALKALOIDS

The application of the ring-closing metathesis (RCM) reaction to the construction of a wide variety of nitrogen-containing ring systems is described. The examples include pyrrolizidine, indolizidine, and quinolizidine derivatives related to azasugars. A formal total synthesis of castanospermine (5) is presented. The utilisation of two RCM steps in the synthetic sequence leading to the multicyclic ABCDE nucleus 7 of the complex alkaloid manzamine A (6) is discussed.

RING-CLOSING METATHESIS MEDIATED SYNTHESIS OF PYRROLIZIDINE AND QUINOLIZIDINE AZASUGARS

Abstract The synthesis of a novel perbenzylated pyrrolizidine starting from 2,3,5-tri- O -benzyl-arabinofuranose and based on a ring-closing metathesis (RCM) reaction is presented. In an analogous procedure, 2,3,5-tri- O -benzylxylopyranose was converted into a hitherto unprecedented quinolizidine azasugar.

An expedient stereoselective synthesis of gluconolactam

Abstract An efficient synthesis of the title compound, starting from glucose, is described.