Access to 3-Prenylated Oxindoles by α-Regioselective Prenylation: Application to the Synthesis of (±)-Debromoflustramine E

Abstract

The development of a rapid, highly efficient, and one-pot synthesis of C3-α-prenylated oxindoles with simple reagents is described. The process is based on zinc-mediated α-regioselective prenylation of 3-acylidene-oxindole with commercially available prenyl bromide using inexpensive CeCl as the catalyst. The new transformation tolerates a wide range of 3-acylidene-oxindoles, providing easy access to a variety of functionalized 3-prenylated oxindoles. The synthetic utility of the approach is verified by formal synthesis of the flustramine family alkaloid (±)-debromoflustramine E.

Copper(I)‐Catalyzed Cascade Cyclization to the Total Synthesis of Hexahydropyrroloindole Alkaloids: Flustramine B and Debromoflustramine B

“…Based on its interesting biological activities and the synthetic challenging of tetrasubstituted stereocenters, which has been attracted significantly attention in organic chemistry. For the past decades, many novel synthetic routes have been reported for the construction of these architectures, and to further access hexahydropyrroloindole (HPI) alkaloids, [13][14][15][16][17][18][19][20][21] such as MacMillan, Trost, Zhang, You and Zhao et al To our knowledge, most routes often relied on substituted indoles or tryptophan derivatives as starting materials, however, only a few reports were based on non-indole or nonoxindole. [15,[22][23][24] To address these limitations, Zhang group [25][26][27][28][29] has developed a novel copper(I)-catalyzed tandem reaction strategy to achieve several natural products of hexahydropyrroloindole alkaloids, such as (À )-Debromoflustramine E, (+)-Chimonanthine, (À )-Ditryptophenaline and (+)-Nocardioazine B et al Based on previous work, to continue our interest in studying the total synthesis of Hexahydropyrroloindole (HPI) alkaloids, herein we report a complementary route for the total synthesis of Flustramine B and Debromoflustramine B via a cascade cyclization process starting from non-indole or non-oxindole catalyzed by Copper (I).…”

Construction of Benzothiophene or Benzothiopheno[2,3-e]azepinedione Derivatives via Three-Component Domino or One-Pot Sequences

“…Thioisatins, the sulfur analogues of isatins, have not drawn much attention in organic synthesis. , Compared to isatins and their derivatives, − the reactions of thioisatins have been limited and under development (Figure ). Based on our recent results, the C–S bond of thioisatins was easily cleaved in the presence of inorganic bases, after which a suitable domino sequence would be triggered to produce the desired sulfur-containing products .…”

Deconstructive Functionalization of Unstrained Cycloalkanols via Electrochemically Generated Aromatic Radical Cations

“…In comparison to batch, the flow process was performed using a lower electrolyte concentration ([ n -Bu 4 NPF 6 ] = 0.05 M vs [ n -Bu 4 NPF 6 ] = 0.1 M) and increased current density ( j anode = 22 mA/cm 2 vs j anode = 7.8 mA/cm 2 ), which resulted in higher productivity (4.1 mmol/h vs 0.08 mmol/h). The 4-methoxyphenyl ketone functionality within 2 can be readily converted to the corresponding ester or amide via Baeyer–Villiger or Beckmann rearrangements, respectively.…”