title: Quararibea Metabolites. 4.(1) Total Synthesis and Conformational Studies of (+/-)-Funebrine and (+/-)-Funebral.
abstract: Syntheses of racemic forms of the main secondary metabolites of Quararibea funebris, (+/-)-funebrine, (+/-)-funebral, and their biogenetic precursor (+/-)-(2S,3S,4R)-gamma-hydroxyalloisoluecine lactone have been developed. In synthetic studies, a new variation of the Paal-Knorr condensation employing titanium isopropoxide was utilized to construct the pyrrole lactone moiety. Two efficient synthetic approaches to the key (+/-)-gamma-amino lactone have been developed, one based on Claisen chemistry and the other on addition reactions to the butenolide ring of beta-angelicalactone. The restricted rotation around the C(sp(3))-N(sp(2)) bond in the pyrrole lactone structures of (+/-)-funebrine, (+/-)-funebral, and related aldehydes has been probed by conformational dynamic studies, and the barriers for interconversion between conformations have been measured by full NMR line-shape analysis. Molecular mechanics (MMX) and a (1)H-(1)H NOE study indicate a distinct preferred conformation for (+/-)-funebrine.
authors.affiliation: Department of Chemistry and Barnett Institute, Northeastern University, Boston, Massachusetts 02115-5096.
authors.forename: Ying
authors.initials: Y
authors.lastname: Dong
authors.forename: Niranjan
authors.initials: N
authors.lastname: Niranjan N Pai
authors.forename: Sheri L.
authors.initials: SL
authors.lastname: Ablaza
authors.forename: Shao-Xia
authors.initials: SX
authors.lastname: Yu
authors.forename: Simon
authors.initials: S
authors.lastname: Bolvig
authors.forename: David A.
authors.initials: DA
authors.lastname: Forsyth
authors.forename: Philip W.
authors.initials: PW
authors.lastname: Le Quesne