Enantioselective synthesis of 3,4-chromanediones via asymmetric rearrangement of 3-allyloxyflavones.
Asymmetric scandium(III)-catalyzed rearrangement of 3-allyloxyflavones was utilized to prepare chiral, nonracemic 3,4-chromanediones in high yields and enantioselectivities. These synthetic intermediates have been further elaborated to novel heterocyclic frameworks including angular pyrazines and dihydropyrazines. The absolute configuration of rearrangement products was initially determined by a nonempirical analysis of circular dichroism (CD) using time-dependent density functional theory (TDDFT) calculations and verified by X-ray crystallography of a hydrazone derivative. Initial studies of the mechanism support an intramolecular rearrangement pathway that may proceed through a benzopyrylium intermediate.
Marié
Jean-Charles
JC
Center for Chemical Methodology and Library Development (CMLD-BU), Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, USA.
Xiong
Yuan
Y
Min
Geanna K
GK
Yeager
Adam R
AR
Taniguchi
Tohru
T
Berova
Nina
N
Schaus
Scott E
SE
Porco
John A
JA
D002384:Catalysis; D002839:Chromans / Q000138:chemical synthesis* / Q000737:chemistry; D002942:Circular Dichroism; D018360:Crystallography, X-Ray; D047309:Flavones / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D012538:Scandium / Q000737:chemistry*; D013237:Stereoisomerism
D002839:Chromans; D047309:Flavones; D012538:Scandium