This article provides a fairly comprehensive overview on olefin metathesis reactions applied as pivotal steps in the total syntheses
of indolizidine alkaloids belonging to the families of castanospermine, deoxycastanospermine and diastereomers thereof, natural or
non-natural compounds that play multiple roles in biological processes. A well-balanced mixture of topics is proposed, covering most
relevant traits of their biological activity, therapeutic applications, and structural similarities to, or differences from, other established
iminosugar drugs. While mainly focussing on a critical discussion of the metathesis-based processes (RCM, CM, RRM), their promoters
and conditions, their advantages and limitations, also shown is how metathesis has contributed to more efficient and shorter protocols for
accessing this important class of antiviral, antitumor, antimetastatic, anti-inflammatory and immunoregulating agents.