Stereocontrol of bilirubin conformation

✍ Scribed by Stefan E. Boiadjiev; David A. Lightner

• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 790 KB
• Volume: 7
• Category: Article
• ISSN: 0957-4166
• DOI: 10.1016/0957-4166(96)00148-6

✦ Synopsis

Optically active, diastereomeric synthetic bitirubin analogs (1 and 2) with an e~-methyl and a ¢3-methyl in each propionic acid side chain were synthesized. Both diastereomers adopt a folded, ridge-tile conformation. The methyls force the pigment to adopt either a left-handed (M) or right-handed (P) helicity. As evidenced by exciton-type circular dichroism spectra, in the (c~S,c~'S,13S,t3'S) diastereomer (1) the M helicity ridge-tile enantiomer is strongly preferred; in the (c~R,a'R,13S,13'S) diastereomer (2),the P helicity conformation is preferred.