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pent-3-enol as a practical starting material for the synthesis of
bicycloproline. The key steps in our synthesis are a Rh(II)-catalyzed
nitrenoid insertion reaction to provide the tert-alkylamine and a
Grubbs’ ring-closing metathesis to form the pyrrolidine ring. We
are currently investigating the regioselectivity of C–H insertions
in polyfunctional substrates for the synthesis of other complex
amino acids. The incorporation of bicycloproline into host struc-
tures and its effects on peptide conformation will be reported in
due course.
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We thank Leticia Montoya (New Mexico State University) and
the Scripps Center for Mass Spectrometry for mass analysis of all
compounds, and Dr. Eileen Duesler (University of New Mexico)
for X-ray studies on compound 23. This work was supported by a
grant from the National Institute of General Medical Sciences
(NIH 1SC2AI081526-01).
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enantiomeric purity of 2 (>95:5) was assessed by conversion to the Mosher
ester and analysis by NMR.
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11. See Supplementary data.
Supplementary data
Supplementary data (experimental procedures, complete spec-
tral data, copies of NMR spectra for new compounds, and X-ray
and for 23) associated with this article can be found, in the online
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