Ak. Kar et Da. Lightner, SYNTHESIS OF BILIN-1,19-DIONES AND BILADIENE-AC-1,19-DIONES WITH C(10) ADAMANTYL AND TERT-BUTYL GROUPS, Journal of heterocyclic chemistry, 35(4), 1998, pp. 795-803
Bilirubin and biliverdin analogs bearing bulky adamantyl and tert-buty
l groups at the central C(10) position were synthesized and their stru
ctures were analyzed by nmr and ultraviolet-visible spectroscopy and b
y molecular mechanics calculations, all of which collectively indicate
d a preference for helical conformations.