First Total Synthesis of (±)-Strychnofoline via a Highly Selective Ring-Expansion Reaction

Abstract

An efficient synthesis of the antitumor alkaloid (+/-)-strychnofoline is documented. Key to the development of the highly convergent strategy delineated is the coupling of a cyclic imine with spiro[cyclopropan-1,3'-oxindole], which takes place in a highly diastereoselective manner. The ability to conduct annulation reactions of spirocyclopropyloxindoles with functionalized cyclic imines provides new avenues for the preparation of this important class of biologically active structures.

Stereoselective Synthesis of Tetrahydroindolizines through the Catalytic Formation of Pyridinium Ylides from Diazo Compounds

“…Cyclopropanes could also undergo non-catalysed ring expansion with pyridine, [31,32] but only starting materials were obtained from reaction of cyclopropane 3 using the latter reaction conditions.…”

Construction of Spiro[pyrrolidine‐3,3′‐oxindoles] − Recent Applications to the Synthesis of Oxindole Alkaloids

“…From 83, (Ϯ)-strychnofoline (84) was obtained in two steps through PictetϪSpengler reaction with N-methyltryptamine, followed by deprotection of the benzyl protecting groups (Scheme 26). [72] Scheme 26. First total synthesis of (Ϯ)-strychnofoline employing the ring expansion reaction of oxindole 80 with cyclic imine 81 Our approach to spirotryprostatin B was driven by our interest in the feasibility of using the magnesium iodide catalyzed ring-expansion reaction for the construction of spiro-[pyrrolidine-3,3Ј-oxindoles] with a higher degree of substitution on the pyrrolidine ring.…”

Hypervalent Iodine Reagents for the Oxidation of Alcohols and Their Application to Complex Molecule Synthesis

“…(36). [63] 36 Porco and co-workers recently reported another interesting tandem intermolecular reaction with 2 in the total synthesis of ()-torreyanic acid (53). In the final step of the synthesis of 53, the DMP-induced tandem oxidation/ electrocyclization/dimerization process starting from 54 followed by treatment with TFA/CH 2 Cl 2 afforded 53 in 80% yield, Eq.…”