Chiral recognition of cyclic alpha-hydroxyketones by CD-sensitive zinc tetraphenylporphyrin tweezer.
A combined chemical/chiroptical microscale protocol for the determination of absolute configurations of cyclic alpha-hydroxyketones is described. The hydroxyl group in cyclic alpha-hydroxyketones is converted into (3-aminopropylamino)acetate (NH2CH2CH2CH2NHCH2COOR), or more generally, according to a newly developed protocol, into (3-hydroxypropylamino)acetate group (HOCH2CH2CH2NHCH2COOR). The resultant conjugated compound forms a 1:1 host-guest complex with a dimeric zinc porphyrin tweezer, which exhibits exciton-coupled bisignate CD spectrum centered around the 420-nm porphyrin Soret band due to induced helicity between the two porphyrins in the complex. The absolute configurations of the alpha-stereogenic center is then determined by comparison of the sign of the observed CD exciton couplet of the complex with that of the preferred porphyrin twist predicted by the Merck Molecular Force Field (MMFFs) method.
Ishii
Hideki
H
Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027, USA.
Chen
Yihui
Y
Miller
Ross A
RA
Karady
Sandor
S
Nakanishi
Koji
K
Berova
Nina
N
D002942:Circular Dichroism; D007659:Ketones / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008665:Metalloporphyrins; D008958:Models, Molecular; D008968:Molecular Conformation; D015394:Molecular Structure; D016339:Spectrometry, Mass, Fast Atom Bombardment; D013237:Stereoisomerism
D007659:Ketones; D008665:Metalloporphyrins; C048955:zinc tetraphenylporphyrin