Synthetic Studies toward Isoschizogamine: Construction of Pentacyclic Core Structure

Vallesamidine and schizozygane alkaloids: rearranged monoterpene indole alkaloids and synthetic endeavours

“…In the same year, Tokuyama and co-workers disclosed a new total synthesis of (−)-isoschizogamine 35 by a late-stage C–H oxidation to construct the key aminal motif. 77,78 Tactically, Tokuyama provides a novel retrosynthetic analysis without referring to Heathcock's type intermediate, leading to the key compound 296 , which could be constructed via a triple cyclisation of 292 (Scheme 32). The preparation of 292 started from catalytic asymmetric hydrogenation of enone 285 and the obtained chiral allylic alcohol 287 underwent a Johnson–Claisen rearrangement to 288 .…”

“…Tokuyama's total synthesis of (−)-isoschizogamine. In the same year, Tokuyama and co-workers disclosed a new total synthesis of (−)-isoschizogamine 35 by a late-stage C-H oxidation to construct the key aminal motif 77,78. Tactically, Tokuyama provides a novel retrosynthetic analysis without referring to Heathcock's type intermediate, leading to the key compound 296, which could be constructed via a triple cyclisation of 292 (Scheme 32).…”