RSC Advances
Paper
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2 The
formation
and
hydrogenation
of
9-
alkylideneuorenes:(a) G. B. Bachman and S. Polansky, J.
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3 The SN2 reaction of 9-lithouorene with haloalkanes:(a)
G. S. Hamilton, R. E. Mewshaw, C. M. Bryant, Y. Feng,
G. Endemann, K. S. Madden, J. E. Janczak, J. Perumattam,
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Scheme 1 Control experiments.
4 The base-catalyzed 9-monoalkylation of uorene with
alcohols:(a) K. L. Schoen and E. I. Becker, J. Am. Chem. Soc.,
1955, 77, 6030; (b) K. L. Schoen and E. I. Becker, Organic
Synthesis, Wiley, New York, 1963, Collect. vol. IV, p. 623; (c)
Also see: ref. 2b.
Scheme 2 A proposed catalytic cycle.
5 The aldehyde/ketone-catalyzed 9-monoalkylation of uorene
with alcohols: J. Chen, Y. Li, S. Li, J. Liu, F. Zheng, Z. Zhang
and Q. Xu, Green Chem., 2017, 19, 623.
6 For selected reviews on the use of alcohols as alkylating
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Science, 2010, 329, 635; (b) T. D. Nixon, M. K. Whittlesey
Conclusions
In summary, we have developed a simple, mild and efficient
protocol for the alkylation of uorene with alcohols in the
presence of potassium tert-butoxide as catalyst. This method
affords a highly green access to 9-monoalkyluorenes. Further
study to expand the scope of substrates is ongoing in our
laboratory.
¨
and J. M. J. Williams, Dalton Trans., 2009, 753; (c) S. Bahn,
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7 It was found that the 9-alkylidene uorene 4 would become
a major product under the same conditions as for the 9-
monoalkyl uorene synthesis except at a lower reaction
temperature of about 70 C. Also see: Table S1 in ESI.†
8 R. F. Schultz and C. F. Smullin, J. Am. Chem. Soc., 1940, 62,
2904.
Conflicts of interest
There are no conicts to declare.
Acknowledgements
ꢀ
The authors thank National Natural Science Foundation of
China (Project No. 21503234 and 21572235) for nancial
support of this work.
9 For selected Meerwein–Ponndorf–Verley reduction reactions,
see: (a) J. Lee, T. Ryu, S. Park and P. H. Lee, J. Org. Chem.,
2012, 77, 4821; (b) C. Battilocchio, J. M. Hawkins and
S. V. Ley, Org. Lett., 2013, 15, 2278; (c) J. Song, B. Zhou,
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Notes and references
1 (a) N. R. Evans, L. S. Devi, C. S. K. Mak, S. E. Watkins,
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S. I. Pascu, A. Kohler, R. H. Friend, C. K. Williams and
A. B. Holmes, J. Am. Chem. Soc., 2006, 128, 6647; (b)
G. Hughes and M. R. Bryce, J. Mater. Chem., 2005, 15, 94; (c)
35916 | RSC Adv., 2019, 9, 35913–35916
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