Some oxidation products of lycoctonine revisited

Abstract

The structure of a chromic acid oxidation product of the norditerpenoid alkaloid lycoctonine (1) was established as hydroxylycoctonal (3) by spectrometric analyses and X-ray crystallography of its reduction product, hydroxylycoctonine (5); the structure of lycoxonine, a chromic acid oxidation product of the lactam, lycoctonam (7), was similarly confirmed as N-ethyl-4,7,8-trihydroxy-1α,6β,14α,16β-tetramethoxy-19-oxoaconitane (8). Reduction of lycoxonine with lithium aluminium hydride gave the 1,14-di-O-methyl ether (12) of the bisnorditerpenoid alkaloid delbine (9).

Rhenium Complexes with Visible‐Light‐Induced Anticancer Activity

“…Application of oxidative selenium chemistry first introduced the double bond between the C8 and C15 carbon atoms; the resulting highly strained enone 20 underwent spontaneous nucleophilic attack by water, which installed the tertiary alcohol at the C8 position. With the advanced intermediate 21 in hand, several redox transformations, including decarboxylative hydroxylation at the C4 position7 and installation of the C4 anthranilate group, finally completed the total synthesis of racemic neofinaconitine ( 8 ) 8. Furthermore, commercially available condelphine ( 2 ) was also converted into optically active neofinaconitine ( 8 ), which confirmed the authenticity of the material that was obtained by total synthesis 9…”

Total Synthesis, Relay Synthesis, and Structural Confirmation of the C18-Norditerpenoid Alkaloid Neofinaconitine

“…32 Amide reduction at C19 in 48 (LiAlH 4 ) then revealed the requisite tertiary amine. The remaining formidable task was selective acylation of the C4 tertiary alcohol in the presence of the C8 tertiary alcohol.…”

“…32 This seemingly superfluous C19-oxidation served two vital purposes. First, it enabled selective demethylation of the C18-methoxy group (BBr 3 ), presumably due to boron precoordination to the C19 carbonyl enabling selective activation of C18 oxygen.…”

Synthesis of the C18‐Norditerpenoid Alkaloid Neofinaconitine: A Lesson in Convergent Synthesis Planning

“…Application of oxidative selenium chemistry first introduced the double bond between the C8 and C15 carbon atoms; the resulting highly strained enone 20 underwent spontaneous nucleophilic attack by water, which installed the tertiary alcohol at the C8 position. With the advanced intermediate 21 in hand, several redox transformations, including decarboxylative hydroxylation at the C4 position [7] and installation of the C4 anthranilate group, finally completed the total synthesis of racemic neofinaconitine (8). [8] Furthermore, commercially available condelphine (2) was also converted into optically active neofinaconitine (8), which confirmed the authenticity of the material that was obtained by total synthesis.…”