Total Synthesis of (+)-3-Demethoxyerythratidinone and (+)-Erysotramidine via the Oxidative Amidation of a Phenol

Abstract

Oxidative amidation chemistry provides a unified route to aromatic Erythrina alkaloids through a sequence that illustrates new principles and improved conditions to effect a crucial eliminative Curtius-Schmidt rearrangement.

Recent Advances in Substrate-Controlled Asymmetric Induction Derived from Chiral Pool α-Amino Acids for Natural Product Synthesis

“…Structurally, these alkaloids consist of cis-2,6-dialkylpiperidine. Vinylogous lactams 72 and 73, which were used as chiral precursors, were More recently, Ciufolini et al described the total synthesis of (+)-erysotramidine (70) using an L-serine derivative (Scheme 14) [41,42]. Advanced oxazoline 67, prepared from L-serine methyl ester (66) via DCC coupling and Burgess reagent-induced cyclization [43], was converted into enone 68 as a precursor for stereoselective Michael cyclization.…”

Bioassay‐guided isolation of potent aphicidal Erythrina alkaloids against Aphis gossypii from the seed of Erythrina crista‐galli L

“…2. In addition, biogenetic considerations on Erythrina alkaloids 20,32,33 and the identical chemical shift of C-3 with known compounds [34][35][36][37] suggested that 1 has an R configuration at C-3. The absolute configuration of C-10 was assigned as R from the Pest Manag Sci 2018; 74: 210-218 NOESY, which indicated that there was an interaction between H-10 and H-4 (Fig.…”

A Short Synthesis of (±)‐3‐Demethoxyerythratidinone by Ligand‐Controlled Selective Heck Cyclization of Equilibrating Enamines

“…Employing the more electron-rich tris(p-methoxyphenyl) phosphine as al igand, however,f avored formation of (AE)-1 (53 %) over (AE)-17 (13 %) (entry 4). Them ost consistent results were obtained with the alkyl phosphine ligand (Cy) 3 Pw hich gave 69 %i solated yield of 1 and just 10 %o ft he isomer (AE)-17 (entry 5) in as ingle telescoped sequence from the ester (AE)-16.T his optimized result concluded a5 -step synthesis of (AE)-1 in 15 %overall yield from pyrrole 7 (Scheme 2).…”

“…Use of chiral ligands for the asymmetric synthesis of (+ +)-1 yielded mixed results;u pt o 38 % ee was observed in favor of (+)-1 but at the expense of product selectivity. 3 PhMe < 10 69 6P d(OAc) 2 P(tBu) 3 PhMe 83 7P d(OAc) 2 (À)-DIOP PhMe 55 40 [c] 8P d(OAc) 2 (R)-i Pr-PHOX PhMe 30 32 [d] [a] 1equiv of TBAI.…”

“…[1] The Erythrina alkaloids display ab road range of pharmacological activities including hypotensive, sedative,n euromuscular blocking,C NS depressing and curare-like activities.T he key structural feature of this family is the tetracyclic tetrahydroisoquinoline core.S ince the first total synthesis of 1 by Tsuda in 1984, [2] this tetracyclic alkaloid has been used by others in order to demonstrate the utility of various synthetic methodologies. [3] Av ery elegant synthesis was recently reported by Reisman, where chiral sulfinyl imine chemistry was used to control the stereochemistry of the key quaternary center, [3d] giving (À)-3-demethoxyerythratidinone in just six steps overall ( Figure 1).…”