BibTex format
@article{Clarke:2016:10.1021/acs.joc.6b02008,
author = {Clarke, J and Bonney, KJ and Yaqoob, M and Solanki, S and Rzepa, HS and White, AJP and Millan, DS and Braddock, DC},
doi = {10.1021/acs.joc.6b02008},
journal = {Journal of Organic Chemistry},
pages = {9539--9552},
title = {Epimeric Face-Selective Oxidations and Diastereodivergent Transannular Oxonium Ion Formation Fragmentations: Computational Modeling and Total Syntheses of 12-Epoxyobtusallene IV, 12-Epoxyobtusallene II, Obtusallene X, Marilzabicycloallene C, and Marilzabicycloallene D},
url = {http://dx.doi.org/10.1021/acs.joc.6b02008},
volume = {81},
year = {2016}
}
RIS format (EndNote, RefMan)
TY - JOUR
AB - The total syntheses of 12-epoxyobtusallene IV, 12-epoxyobtusallene II, obtusallene X, marilzabicycloallene C, and marilzabicycloallene D as halogenated C<inf>15</inf>-acetogenin 12-membered bicyclic and tricyclic ether bromoallene-containing marine metabolites from Laurencia species are described. Two enantiomerically pure C<inf>4</inf>-epimeric dioxabicyclo[8.2.1]tridecenes were synthesized by E-selective ring-closing metathesis where their absolute stereochemistry was previously set via catalytic asymmetric homoallylic epoxidation and elaborated via regioselective epoxide-ring opening and diastereoselective bromoetherification. Epimeric face-selective oxidation of their Δ<sup>12,13</sup> olefins followed by bromoallene installation allowed access to the oppositely configured 12,13-epoxides of 12-epoxyobtusallene II and 12-epoxyobtusallene IV. Subsequent exploration of their putative biomimetic oxonium ion formation-fragmentations reactions revealed diastereodivergent pathways giving marilzabicycloallene C and obtusallene X, respectively. The original configurations of the substrates evidently control oxonium ion formation and their subsequent preferred mode of fragmentation by nucleophilic attack at C<inf>9</inf> or C<inf>12</inf>. Quantum modeling of this stereoselectivity at the ωB97X-D/Def2-TZVPPD/SCRF = methanol level revealed that in addition to direction resulting from hydrogen bonding, the dipole moment of the ion-pair transition state is an important factor. Marilzabicycloallene D as a pentahalogenated 12-membered bicyclic ether bromoallene was synthesized by a face-selective chloronium ion initiated oxonium ion formation-fragmentation process followed by subsequent bromoallene installation.
AU - Clarke,J
AU - Bonney,KJ
AU - Yaqoob,M
AU - Solanki,S
AU - Rzepa,HS
AU - White,AJP
AU - Millan,DS
AU - Braddock,DC
DO - 10.1021/acs.joc.6b02008
EP - 9552
PY - 2016///
SN - 0022-3263
SP - 9539
TI - Epimeric Face-Selective Oxidations and Diastereodivergent Transannular Oxonium Ion Formation Fragmentations: Computational Modeling and Total Syntheses of 12-Epoxyobtusallene IV, 12-Epoxyobtusallene II, Obtusallene X, Marilzabicycloallene C, and Marilzabicycloallene D
T2 - Journal of Organic Chemistry
UR - http://dx.doi.org/10.1021/acs.joc.6b02008
VL - 81
ER -