Synthesis of polyhydroxylated alkaloids via allene cyclisation

Abstract

Polyhydroxylated alkaloids, a class of natural products prevalent in plants, have attracted the interest of many due to their rich biological activities and complex chemical structures. These alkaloids are generally made up of small ring systems with dense chiral information, thus making their synthesis a challenging endeavour for chemists. While the use of natural sugars and chiral building blocks are commonplace in the synthesis of these alkaloids, we envision that these functionalised heterocycles could be synthesised from non-chiral starting materials via the intramolecular cyclisation of allenes bearing nucleophiles. The gold-catalysed nucleophilic cyclisation of allenes has generated much interest in recent times due to its ability to access varied ring systems efficiently. In this thesis, the synthesis of various polyhydroxylated alkaloids, utilising the gold-catalysed nucleophilic cyclisation of allenes as the key transformation, is described.