Part I : towards a total synthesis of papulacandin D. Part II: towards a total synthesis of amphidinolide X.
Goh, Hong Heng.
Date of Issue2010
School of Physical and Mathematical Sciences
The facile β,γ- to α,β-isomerization upon hydrolysis of the three-carbon homologated Wittig oleﬁnation product using the homoenolate anion equivalent (3,3-dimethoxypropyl)triphenylphosphonium salt has always been viewed as a complicating side reaction in organic synthesis. Perhaps arising from such prejudiced views, its utility and practicality to organic syntheses has long been overlooked. In this thesis, we ﬁrst surveyed the ways similar phosphonium salt-based homoenolate anion equivalents had been used in organic synthesis and uncovered the dearth of information on the application of this facile isomerization to organic synthesis. Thence we embarked on a systematic screening to ﬁrst establish the substrate scope of this facile isomerization, before commencing on the application of this methodology to the syntheses of two natural products — papulacandin D and amphidinolide X. We report herein our ﬁndings on the feasibility of applying this method for the generation of α,β-unsaturated aldehydes via a three-carbon homologation/isomerization, that holds potential for shortened synthetic routes and offers the possibility of further synthetic manipulations typiﬁed by aldehydes belonging to such a class.
DRNTU::Science::Chemistry::Organic chemistry::Organic synthesis