10.1002/ejoc.202000979
European Journal of Organic Chemistry
Scheme 4. Proposition of mechanism
eq) was stirred in MeCN for 5 min. Then, TMSCl (10
eq) was added to the solution which was stirred for 24
h at rt. The reaction was then hydrolyzed for 5 min.
with H2O (5 mL) and extracted with CH2Cl2. Organic
layers were dried over MgSO4 and concentrated under
reduced pressure to give a residue which was purified
by chromatography on silica gel to give the expected
carbonyl compound which have identical NMR
spectra with starting ketones.
Acknowledgements
Authors gratefully acknowledge support of this project by CNRS
and Univ. Paris-Saclay. Yunxin Yao and Guangkuan Zhao thank
the Chinese Scholarship Council for Ph.D. funding.
which adds H2O (from reagents, CH3CN or during
hydrolysis) to promote hemithioketal IV which is then
activated into a sulfonium intermediate V (having or
not H. With no H as in 1r or 1s, V finally
rearranges into the desired ketone 2e.[32] For
dithiolanes prepared from enolizable ketones as 1d,
the same (a) pathway could be followed, but it is also
reasonable to consider an additional pathway (b) in
which an iodide deprotonates intermediate V to furnish
an enol species which tautomerizes into ketone 2e.
Since dithioacetals having H can evolve according to
two different pathways, this can explain that these
entities are more straightforward to deprotect than
diarylthioketals counterparts. It is noted that Nicolaou
has previously proposed a similar mechanism for the
deprotection of S,S-acetals and ketals using IBX.[33]
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Experimental Section
A general experimental procedure is described as
following: a mixture of thioketal (100 mg) and NaI (10
5
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