Preparation of (2R,3S)-1,2-epoxypent-4-en-3-ol, a new chiral building block for the synthesis of (+)-endo- and (–)-exo-brevicomin

Total Synthesis of Biologically Active Natural Products Based on Highly Selective Synthetic Methodologies

“…Our basic idea to access compound 43 began with asymmetric epoxidation 62,63) of σ-symmetrical dialkenylcarbinol 47 and then the sequence proceeded through Mitsunobu inversion, introduction of a nitrogen atom by taking advantage of the epoxy alcohol functionality, construction of a Z-unsatuChart 12. Second-Generation Synthesis of Dysiherbaine Chart 13.…”

Stereocomplementary Desymmetrizations of Divinylcarbinols by Zirconium(IV)‐ vs. Titanium(IV)‐Mediated Asymmetric Epoxidations

“…Bis(cis-configured) divinylcarbinols (!anti-12 and anti-13) had not been involved in this transformation before. Using t-BuOOH and a dialkyl d-or l-tartrate as before but now adding ZrA 4 , the divinylcarbinols of the present study were desymmetrized by conversion into the non-racemic Scheme 2. SAE of achiral secondary allyl alcohols ("divinylcarbinols").…”

“…They were pioneered by the groups of Takano [4] and Jäger [5] studying SAEs of penta-1,4-dien-3-ol (3, R 1 = R 2 = H). SAEs of symmetrically substituted penta-1,4-dien-3-ols 3 (R 1 and/or R 2 ¼ 6 H, "divinyl carbinols") proceed similarly.…”

“…Penta-1,4-dien-3-ol was epoxidized asymmetrically by the groups of Takano, [4] Jäger, [5] and Schreiber, [6] yielding monoepoxide anti-6. The ee of anti-6 increased dramatically with time [84% ee (after 3 h) to > 97% ee (after 140 h)].…”

“…[12] Employing t-BuOOH/dialkyl d-or ltartrate/TiA C H T U N G T R E N N U N G (O-i-Pr) 4 mixtures as the oxidant, non-racemic monoepoxy alcohols anti-12-14 were obtained. Bis(cis-configured) divinylcarbinols (!anti-12 and anti-13) had not been involved in this transformation before.…”