Two new isoprenoidal ketones related to Botryococcus braunii in the Chinese Maoming Basin
发布时间：2024-01-08
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名 称
Two new isoprenoidal ketones related to Botryococcus braunii in the Chinese Maoming Basin
科技资源标识
CSTR:11738.14.NCDC.XDA14.PP4376.2024
DOI
10.1016/j.orggeochem.2019.103946
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摘 要
We report the spectroscopy-based (NMR, HRMS, IR) reassignment of the structures of two previously mis-identified saturated methyl ketones (formerly C15 ketone: 5,9-dimethyl-6-isopropyl-2-decanone and C18 ketone: 4,9,11-trimethyl-6-isopropyl-2-dodecanone) in the Maoming oil shale to: 5,6,9,10-tetramethy lundecan-2-one and 4,7,8,11,12-pentamethyltridecan-2-one, respectively. A diagenetic pathway is proposed to explain the isotopic and structural closeness between these two methyl ketones and recently identified saturated C31 alcohols, C32 aldehydes and C33 ketones (all with a unique methyl group b to the sole quaternary carbon in their skeletons) obtained from the same Maoming Basin sediments. The pathway involves, firstly, epoxidation, hydration, oxidation and double decarboxylation of the C33 botryococcene to C31 botryococcene. Subsequent photo- or autoxidation of the internal double bond around the quaternary carbon in the C31 botryococcene in an oxic environment leads to the formation of a C31 hydroperoxy-alkene. A heterolytic (Hock-type) or homolytic cleavage of the hydroperoxy-alkene around the quaternary carbon then gives rise to the C15 and C18 unsaturated methyl ketones, respectively. The so-formed unsaturated ketones are then geochemically stabilized by hydrogenation in an anoxic environment.
Liao Jing. Two new isoprenoidal ketones related to Botryococcus braunii in the Chinese Maoming Basin. 国家冰川冻土沙漠科学数据中心(http://www.ncdc.ac.cn), 2024. https://cstr.cn/CSTR:11738.14.NCDC.XDA14.PP4376.2024.
Liao Jing. Two new isoprenoidal ketones related to Botryococcus braunii in the Chinese Maoming Basin. 国家冰川冻土沙漠科学数据中心(http://www.ncdc.ac.cn), 2024. https://www.doi.org/10.1016/j.orggeochem.2019.103946.
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CSTR:11738.14.NCDC.XDA14.PP4376.2024
10.1016/j.orggeochem.2019.103946