title: Regiospecific, enantiospecific total synthesis of C-19 methyl substituted sarpagine alkaloids dihydroperaksine-17-al and dihydroperaksine.
abstract: The optically active tetracyclic ketone 8 was converted into the pentacylic core 14 of the C-19 methyl substituted N(a)-H sarpagine and ajmaline alkaloids via a critical haloboration reaction. The ketone 14 was then employed in the total synthesis of 19(S),20(R)-dihydroperaksine-17-al (1) and 19(S),20(R)-dihydroperaksine (2). The key regioselective hydroboration and controlled oxidation-epimerization sequence developed in this approach should provide a general method to functionalize the C(20)-C(21) double bond in the ajmaline-related indole alkaloids.
authors.affiliation: Department of Chemistry & Biochemistry, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53201, USA.
authors.forename: Rahul V
authors.initials: RV
authors.lastname: Edwankar
authors.forename: Chitra R
authors.initials: CR
authors.lastname: Edwankar
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Deschamps
authors.forename: James M
authors.initials: JM
authors.lastname: Cook
mesh_terms: D000114:Acetylene / Q000737:chemistry; D026121:Indole Alkaloids / Q000138:chemical synthesis* / Q000737:chemistry*; D008745:Methylation; D008958:Models, Molecular; D015394:Molecular Structure; D010084:Oxidation-Reduction; D013237:Stereoisomerism
chemical_list: C465585:19(S),20(R)-dihydroperaksine; C465584:19(S),20(R)-dihydroperaksine-17-al; D026121:Indole Alkaloids; D000114:Acetylene; C475809:sarpagine