Journal of the American Chemical Society
Communication
boron tribromide to afford (+)-ferruginol 14 in 84% yield over
2 steps. To access (+)-hinokiol, (+)-4e was oxidized to the
sulfoxide 7e, converted to vinyl sulfide 9e, and hydrolyzed to
ketone 10e in 83% yield over 3 steps. Substrate-controlled
reduction using sodium borohydride afforded secondary
alcohol 16 in 88% yield with a 12:1 epimer ratio in favor of
the desired configuration. Finally, demethylation of the phenol
by the method of Hoye29 afforded (+)-hinokiol 15.
AUTHOR INFORMATION
Corresponding Author
ORCID
Notes
The authors declare no competing financial interest.
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By analogy to previous mechanistic work,14a,b the catalytic
cycle in Figure 1 is proposed. With assistance of a proton
provided by HFIP, sulfenylating agent 1 transfers the arylthio
group to catalyst 2 to generate cationic complex i.30 This highly
electrophilic complex reacts with the distal alkene of the
polyene substrate 3 to generate an enantiomerically enriched
thiiranium ion ii and regenerate the catalyst 2. Species ii is
opened diastereospecifically in the cationic cascade process3
that is terminated by either arene or phenol capture to afford
the observed product 4.
ACKNOWLEDGMENTS
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This paper is dedicated to the memory of Prof. Edwin Vedejs.
We are grateful to the National Institutes of Health (R01
GM85235) for generous financial support. We also thank the
UIUC SCS support facilities (microanalysis, mass spectrometry,
and NMR) for their assistance.
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Figure 1. Proposed catalytic cycle.
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ASSOCIATED CONTENT
* Supporting Information
The Supporting Information is available free of charge on the
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Experimental procedures and characterization data for all
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