Recent Studies on the Regioselective C-Protonation of Enol Derivatives using Carbonyl-Containing Proton Donors

Enolate protonation can occur by two different pathways. With strong acids regioselective protonation generally occurs on the oxygen of the enolate to give an enol and then acid catalysed tautomerisation leads directly to the thermody-namically preferred carbonyl motif. However, with much weaker acids kinetic protonation on carbon can occur to give directly the carbonyl derivative. This review discuss recent developments into the use of chelating acids to promote this stereochemically important C-protonation and we comment on factors that appear to promote this selectivity.

Total synthesis of (±)-20S-hydroxy-1,2-dehydro-pseudoaspidospermidine via a C–H activation/transannular cyclization strategy

A total synthesis to the pseudoaspidospermidine family via a C–H activation/transannular cyclization strategy has been accomplished.

Study on the total synthesis of velbanamine: Chemoselective dioxygenation of alkenes with PIFA via a stop-and-flow strategy

A "stop-and-flow" strategy was developed for the chemoselective dioxygenation of alkenes with a PIFA-initiated cyclization. This method is conceived for the desymmetrization of seco-diene, and a series of substituted 5-hydroxymethyl-γ-lactones were constructed after hydrolysis. This strategy also differentiates terminally substituted alkenes and constitutes a potentially novel synthetic approach for the efficient synthesis toward velbanamine.