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Chiroptical Properties of Phorbol‐12, 13, 20‐triacetate and Some Other Phorbol Derivatives
Author(s) -
Snatzke Günther,
Hruban Ladislav,
Snatzke Feliksa,
Schmidt Rainer,
Hecker Erich
Publication year - 1976
Publication title -
israel journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.908
H-Index - 54
eISSN - 1869-5868
pISSN - 0021-2148
DOI - 10.1002/ijch.197600010
Subject(s) - chemistry , phorbol , lone pair , phorbol ester , oxygen atom , atom (system on chip) , spectral line , stereochemistry , organic chemistry , protein kinase c , molecule , physics , astronomy , computer science , embedded system , enzyme
The CD spectra of phorbol and of some of its derivatives, such as its 12, 13, 20‐triacetate 1, show at least four bands. Three of them (called I, III, and IV) correspond to the R‐, K‐, and (perhaps) second n → π*‐transition, respectively, of the enone system; the fourth band around 260 nm (band II) is of π → π*‐origin and could be ascribed to an interaction of the lone pair of electrons on the oxygen atom at C(4) with the C=C‐C=O system. The signs of the R‐band as well as the K‐band Cotton effects are very sensitive to chemical modifications around the chromophoric system in the cyclopentenones investigated. The absolute configuration of phorbol may be derived from the CD spectra of some of its derivatives, and, in particular, from the application of the “dibenzoate rule” to 12, 13‐di‐O‐benzoyl phorbol‐20‐acetate (4).