An efficient enantioselective total synthesis of pyrrolo-[2,1-c][1,4]benzodiazepine (PBD) monomers (S)-(−)-barmumycin and (S)-(+)-boseongazepine B was achieved through a stereocontrolled strategy, which relies on a proline catalysed asymmetric α-amination and ester α-ethylenation.
Herein, we describe a versatile transition metal/ oxidant free synthesis of the chiral 2H-1,4-benzoxazines through chiral phosphoric acid (CPA) catalyzed enantioselective desymmetrization of prochiral oxetanes (30 examples) in up to 99% yield and 99% enantioselectivity under mild reaction conditions. The reported strategy not only complements the conventional 2H-1,4benzoxazine synthetic strategies but also provides access to key intermediates of therapeutic candidates, i.e., prostaglandin D2 receptor antagonist and M1 positive allosteric modulator (PAM) compound VU0486846.Letter pubs.acs.org/OrgLett
An operationally simple and concise stereoselective synthesis of both natural 3R, 5 S gingerdiol and 3 S, 5 S gingerdiol has been achieved from achiral n‐heptanal by employing iterative proline catalysed α‐aminoxylation, followed by Horner−Wadsworth−Emmons or Wittig olefination reactions as key steps. The adducts formed in high enantiopurity as well as syn or anti‐1,3‐diols units were synthesized with excellent diastereoselectivity from γ‐hydroxy aldehyde by using D or L‐ proline.
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