Catalytic Insertion Reactions into the Cyclopropane Ring Syntheses of Various Belactosin C Congeners and Analogues

Br MeO CO 2 Me CO 2 Me O MeO N Ph Ph Yb(OTf) 3 (10 mol %) 4 MS, toluene, r.t.21a 22a 17a 19a 20 Nakadomarin A Å 74% Scheme 6. Use of an insertion reaction in the total synthesis of the tetracyclic core of Nakadomarin A. 18 It has also been employed in the synthesis of (+)-Philantidine (23) (Scheme 7). 19CHO CO 2 Me MeO 2 C + N O PMB CO 2 Me MeO NHOH PMBO PMBO MeO 2 C N O H O O 22b 17-vin 21b 19b 23 (+)-Philantidine Yb(OTf) 3 (10 mol %) 4 MS, toluene, r.t.Å 86% Scheme 7. Application of an insertion reaction in the total synthesis of (+)-Philantidine 23.19 CO 2 Me CO 2 Me + N Ph Ph Me O N O Me MeO 2 C CO 2 Me CO 2 Me CO 2 Me Ph