Synthesis studies directed toward gelsemine. Preparation of an advanced pentacyclic intermediate

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

“…[49] Among the synthesis of spiro[pyrrolidine-3,3Ј-oxindole] alkaloids, Overman's synthesis of spirotryprostatin B (5) relies on an asymmetric Heck reaction followed by trapping of an η 3 -allylpalladium species by a tethered nitrogen nucleophile. [50] Key intermediate 50 was accessed from a known allylic alcohol in eight steps.…”

Directed Mizoroki–Heck Reactions

“…In the context of a synthetic endeavor, Overman reported an intriguing case of a π-donor discriminating facial selectivity in an intramolecular MizorokiHeck reaction (Scheme 19) [68,69]. The configuration at the oxindole quaternary carbon of gelsemine (not shown) set in this cyclization was found to be 188 M. Oestreich…”

“…Alkene-directed, diastereoselective Mizoroki-Heck cyclization by Overman [68,69] dependent on the presence of a halide ligand coordinated to the palladium catalyst. Under ligandless reaction conditions (in the absence of phosphane ligands, scenario 1), aryl bromide 71 was preferentially cyclized to 74 (dr = 89 : 11) with good diastereoselectivity (71 → 74).…”

Transition‐Metal‐Mediated Routes to 3,3‐Disubstituted Oxindoles through Anilide Cyclisation

“…Later, the cyclisation precursor 16, its triflate analogue and related structures were employed for the evaluation of ligands in the asymmetric Heck variants. [22] Subsequently, Overman and co-workers published the synthesis of the advanced intermediate 19 (Table 1) [23] for the preparation of gelsemine (15). In the original publication, they obtained a mixture of isomeric products with only a slight preponderance of the desired diastereoisomer Scheme 3.…”