Hetero-annulation of carbohydrates
The aim of the research to be undertaken is the synthesis of hetero-annulated glucose derivatives. In particular the synthesis of five-, six-, and seven- and eight-membered N-containing fused heterocycles is desired, with the nitrogen attached at the C-2 and C-3 position of the sugar ring. Emphasis is placed upon using the sugar ring as a scaffold to enable diastereoelective synthesis. A variety of synthetic techniques are to be employed to achieve ring-closure, especially reductive lamination, ring-closing metathesis and photochemical methods of annulation. (Fig. 9206A).;Such compounds could be useful as precursors to alkaloid synthesis due to the huge range of methods for the conversion of pyranosides to other ring systems. In addition, previous work has shown that such compounds have an inhibitory effect on glycoside processing enzymes. The pyrollidines synthesised have been tested as Glycosidase inhibitors, and some have been shown to be weak specific beta-Galactosidase inhibitors.;Using similar techniques as those employed to produce the lactam above, 2,O- and 3,O-fused lactones were also produced, with dimerised by-products also isolated. Intramolecular photocyclisation was also employed to produce complex multicyclic fused carbocyles. (Fig. 9206B).;Synthesis of N-linked amino sugar dimers was also achieved, and initial attempts at deprotection made. (Fig. 9206C).