4
Tetrahedron
failed to provide a greater yield of 25 (17% yield). All
action studies will be explored to elucidate the means at which
this family elicits their cytotoxic properties.
optimization conditions with these reductants failed to afford 25
in yields greater than 19%. Subjecting 24 to 2.5 equivalents of
DIBAl-H in CH
Cl
2 2
at -78 °C afforded 25 in 92% yield (Scheme
Acknowledgements
5). With 25 in hand, efforts towards cyclopropanation and ring
opening could be performed. Non-facially selective
cyclopropanation conditions were attempted first in the efforts to
prove that our proposed key-steps for the synthesis of
lagunamide C was feasible. The initial attempts of
We would like to thank Kansas State Universities Office of
Research and Department of Chemistry for funding this work
through providing startup capital. We are especially grateful to
the Johnson Cancer Center at KSU for providing a summer
graduate research fellowship for CW and funding this and related
work through an innovative research award. We would like to
thank Olivia Haney for her technical assistance in the assembly
of this manuscript. This paper is warmly dedicated to Emeritus
Professor Marcus Meilahn in recognition and appreciation of his
teaching and mentorship.
2 2 2 4
cyclopropanation with Et Zn, CH I , and TiCl at 0 °C failed to
provide any of the desired material, which led us to explore
temperature optimization. Starting the reaction at 0 °C and then
lowering to -20 °C failed to provide any product, as did the
increase of temperatures. To our surprise, setting up the reaction
at 0 °C and then warming to room temperature, 45 min post
reagent addition, led to a 3% yield of 26. Exclusion of TiCl
4
under the same conditions resulted in an increase in yield to 48%,
and upon running the reaction overnight resulted in a 95%
conversion to the desired cyclopropanated material 26 as a
mixture of diastereomers. Mesylate protection of the alcohol was
Supplementary Data
Supplementary data associated with this article can be found in
the online version, at htts://doi.org/10.1016/j.tetlet.2017.09.071.
accomplished with methanesulfonyl chloride, NEt
The material was subsequently converted to the iodine
counterpart (27) with NaI in acetone with an 80% yield over the
-steps. The stability of 27 was found to be fleeting (1-2 h) and
3 2 2
in CH Cl .
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