Journal of the American Chemical Society
Communication
to aldehyde is reversible under gold catalysis. This reasoning is
also consistent with the 5:1 cis/trans ratio of 3ae observed in
this experiment, which falls between the expected ratio of 4:1 if
there were no reversion and the 7:1 ratio reported in Table 3.
Based on these studies, the first phase of the reaction
resulting in the formation of a homopropargylic alcohol should
follow what we initially designed (see Scheme 1B), where the
tertiary amine-functionalized phosphine ligand L1 is essential
for the success; moreover, the gold catalysis appears to be
reversible. The subsequent cyclization is again enabled by the
bifunctional ligand and involves an unexpected silyl migratio-
n.8a,b Its mechanism is currently examined by DFT calculations
and will be disclosed in future. Notably, the cyclization also
serves to drive the reaction to completion.
studies, transformation of the product, NMR spectra
Crystallographic data for 3ma (CIF)
AUTHOR INFORMATION
Corresponding Author
ORCID
■
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
Synthetic transformations of these dihydrofurans were then
explored by using 3aa as the substrate, which was prepared in a
2-mol scale without any issue (Scheme 2). For example, 3aa
We thank the NSF (CHE 1800525) and NIGMS
(R01GM123342) for generous financial support. T.L. thanks
the China Scholarship Council for a scholarship and the
financial support from the NSFC (21602120).
Scheme 2. Synthetic Applications (Ar = p-NO2Ph)
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ASSOCIATED CONTENT
* Supporting Information
The Supporting Information is available free of charge on the
■
S
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Reactions of Allenylmetal Compounds. In Modern Allene Chemistry;
Krause, N., Hashmi, A. S. K., Eds.; Wiley-VCH Verlag GmbH & Co.
KGaA: 2004; Vol. 1, pp 493−592. (b) Yamamoto, H. 1.3 - Propargyl
General information, preparation of silylated alkynes,
synthesis of dihydrofuran, X-ray of 3ma, mechanism
D
J. Am. Chem. Soc. XXXX, XXX, XXX−XXX