38602-31-2Relevant academic research and scientific papers
Oxyfunctionalization of unactivated C-H bonds in triterpenoids with tert-butylhydroperoxide catalyzed by meso-5,10,15,20-tetramesitylporphyrinate osmium(II) carbonyl complex
Ogawa, Shoujiro,Wakatsuki, Yasuo,Makino, Mitsuko,Fujimoto, Yasuo,Yasukawa, Ken,Kikuchi, Takashi,Ukiya, Motohiko,Akihisa, Toshihiro,Iida, Takashi
experimental part, p. 165 - 171 (2010/06/19)
A system consisting of meso-5,10,15,20-tetramesitylporphyrinate osmium(II) carbonyl complex [Os(TMP)CO] as a precatalyst and tert-butylhydroperoxide (TBHP) as an oxygen donor is shown to be an efficient, regioselective oxidant system for the allylic oxidation, ketonization and hydroxylation of unactivated C-H bonds in a series of the peracetate derivatives of penta- and tetracyclic triterpenoids. Treatment of the substrates with this oxidant system afforded a variety of novel or scarce oxygenated derivatives in one-step. Structures of the isolated components, after chromatographic separation, were determined by spectroscopic methods including GC-MS and shift-correlated 2D-NMR techniques. Factors governing the regioselectivity and the possible mechanism for the oxyfunctionalization of the unactivated carbons are also discussed.
1H and 13C NMR Assignments for Lanostan-3β-ol Derivatives: Revised Assignments for Lanosterol
Emmons, Gary T.,Wilson, William K.,Schroepfer, George J. Jr
, p. 1012 - 1024 (2007/10/02)
1H and 13C NMR assignments are presented for 30 oxygenated lanostane derivatives, including lanosterol, dihydrolanosterol, 7-ketolanosterol, agnosterol, 24,25-epoxylanosterol, 8α,9α-epoxylanostan-3β-ol, three 15-oxygenated derivatives of lanost-7-en-3β-ol, lanostane-3β,7α-diol, lanostane-3B,9α-diol and their acetates.These assignments, which were largely determined by a combination of DEPT, one-bond and long-range 13C-1H chemical shift correlation and lanthanide-induced shift experiments, are not dependent on previously reported assignments, several of which were found to be incorrect. 1H and 13C acetylation shifts for lanostan-3β-ols were sufficiently invariant among the sterols studied that they were useful for assigning carbons in rings A and B.The acetylation shifts reported for lanostan-3β-ols were extended and partially revised.-- Key Words 1H and 13C NMR Oxygenated lanostane derivatives Spectral assignment Lanthanide-induced shifts Long-range HECTOR Acetylation shifts
CYCLOROYLENOL, A CYCLOPROPANE CONTAINING EUPHOID FROM EUPHORBIA ROYLEANA
Vijaya, S. Bhat,Vimal, S. Joshi,Dwipin, D. Nanavati
, p. 5207 - 5210 (2007/10/02)
Cycloroylenol, a new tetracyclictriterpene in the latex of Euphorbia royleana Boiss is shown to have structure (1a)
