The effect of carbonyl on the isomerization of a galanthan ring system and total synthesis of (±)-β-lycorane

Abstract

Lycorine-type alkaloids are privileged structures in the drug development due to its attractive biological activities. In this paper, the carbonyl on the C ring was proved to have played a...

Synthetic Approaches to α‐, β‐, γ‐, and δ‐Lycoranes

“…Besides cycloaddition approaches, other groups have taken advantage of conjugated additions to prepare both racemic and asymmetric lycoranes. [60,61] For instance, the synthesis of (�)-γ-lycorane was reported by Tu (Scheme 13). [62] He took advantage of the kinetic enolate of 93, which was subjected to a Michael reaction with nitro alkene 94 to form compound 95.…”

“…This oxoindole has been reported by the same group as an intermediary for the synthesis of γlycorane. [157] Liu et al [182] also reported a synthesis of β-lycorane through Michael addition-elimination reactions. Reaction between 421 and nitroolefin 174 in basic conditions produced 422 in 91 % yield.…”

Total Synthesis of (+)-Pancratistatin and Its Potent Topo I Inhibition Activity Studies

“…Recently, we have developed an intermolecular Michael addition of racemic nitroalkene with aryl lithium reagent as a key strategy to accomplish the total synthesis of (±)-βlycorane (Figure 2B). 18 This Michael addition was easy to handle, cost-effective, and highly diastereoselective. We envisioned that the use of a chiral nitroalkene in the similar Michael addition may afford the key chiral intermediate leading to (+)-pancratistatin (1), and consequently allowed its efficient preparation (Figure 2C).…”

“…Recently, we have developed an intermolecular Michael addition of racemic nitroalkene with aryl lithium reagent as a key strategy to accomplish the total synthesis of (±)-β-lycorane (Figure B) . This Michael addition was easy to handle, cost-effective, and highly diastereoselective.…”

Catalytic, Asymmetric Total Synthesis of (+)-α-, (+)-β-, (+)-γ-, and (−)-δ-Lycorane

“…Activities such as AChE inhibitory, anticancer, cytostatic, antivirus, and antifungal activities have been discovered in these natural products. , Among >600 Amaryllidaceae alkaloids, lycorane is a representative of the lycorine class in which three contiguous chiral centers are embedded in a minimally substituted framework . Despite the extensive effort by various research groups to implement an effective total synthesis of lycorane since the first report by Hill and co-workers in 1962, the published synthetic strategies remain mostly racemic, and the asymmetric syntheses, particularly catalytic asymmetric ones, are limited . Furthermore, in known asymmetric methods, a thorny issue, asymmetric total synthesis for all stereoisomers, could not be tackled.…”