title: Stereocontrolled synthesis of substituted chiral piperidines via one-pot asymmetric 6π-azaelectrocyclization: asymmetric syntheses of (-)-dendroprimine, (+)-7-epidendroprimine, (+)-5-epidendroprimine, and (+)-5,7-epidendroprimine.
abstract: The asymmetric one-pot 6π-azaelectrocyclization of alkenyl vinyl stannane, ethyl (Z)-2-iodo-4-oxobutenoate, and (-)-7-isopropyl-cis-aminoindanol in the presence of a Pd(0) catalyst stereoselectively produced the tetracyclic aminoacetal compounds, resulting from the four-bond formation accompanying by controlling the stereochemistry at the two asymmetric centers. The produced cyclic aminoacetals can be regarded as synthetic precursors of substituted chiral piperidines, and the syntheses of 2,4- and 2,4,6-substituted piperidines were realized from the obtained aminoacetals by the stereoselective hydrogenation of the double bond conjugated with the C-4 ester group and alkylation at the aminoacetal moiety. In addition, the stereoselective synthesis of an indolizidine alkaloid, (-)-dendroprimine, and its three stereoisomers, (+)-7-epidendroprimine, (+)-5-epidendroprimine, and (+)-5,7-epidendroprimine, were achieved.
authors.affiliation: School of Science and Technology, Kwansei Gakuin University, Gakuen 2-1, Sanda, Hyogo 669-1337, Japan. tkoba@toyaku.ac.jp
authors.forename: Toyoharu
authors.initials: T
authors.lastname: Kobayashi
authors.forename: Futoshi
authors.initials: F
authors.lastname: Hasegawa
authors.forename: Yoshikatsu
authors.initials: Y
authors.lastname: Hirose
authors.forename: Katsunori
authors.initials: K
authors.lastname: Tanaka
authors.forename: Hajime
authors.initials: H
authors.lastname: Mori
authors.forename: Shigeo
authors.initials: S
authors.lastname: Katsumura
mesh_terms: D000080:Acetals / Q000138:chemical synthesis*; D000478:Alkylation; D002384:Catalysis; D003500:Cyclization; D004952:Esters / Q000737:chemistry; D007189:Indans / Q000737:chemistry; D007212:Indolizines / Q000138:chemical synthesis*; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D010165:Palladium / Q000737:chemistry*; D010880:Piperidines / Q000138:chemical synthesis*; D013237:Stereoisomerism
chemical_list: D000080:Acetals; D004952:Esters; D007189:Indans; D007212:Indolizines; D010880:Piperidines; C116915:aminoindanol; C488243:dendroprimine; D010165:Palladium