Withanolide A: synthesis and structural requirements for neurite outgrowth

The exploration of different routes leading to the stereoselective synthesis of the neuritogenic steroid withanolide A is reported in full detail. Notable features of the synthesis include a Corey–Seebach homologation, a vinylogous aldol reaction, a singlet oxygen Schenck-ene reaction, and finally, a late-stage Wharton transposition. Semi-synthetic elaboration of the natural product resulted in 15 derivatives allowing a better understanding of its inherent reactivity pattern as well as its biological properties related to neuronal differentiation and neurite outgrowth.