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OH
OPoc
MoS
4
2-
,
CH
3
CN
28°C, 3h
O
O
HO
BnO
HO
BnO
OBn
OBn
OMe
OMe
95%
O
MoS
4
2-
,
CH
3
CN
28°C
Ph
CbzO
O
O
Ph
O
CbzO
PocO
OMe
OH
OMe
92%
O
MoS
4
2-
,
CH
3
CN
28°C
Ph
O
O
Ph
AcO
O
AcO
PocO
OMe
HO
OMe
95%
FIGURE 1.30
High-yielding removal of propargyloxycarbonyl (Poc) group developed by
Sridhar and Chandrasekaran [48].
1.6 CONCLUSION
We hope that the present review convincingly shows click chemistry to be an excep-
tionally useful methodology not only applicable to coupling larger molecular units
but also when such coupling must be later somehow reversed. The proposed strategy
of using sacrificial units is simple and should become the approach of choice when
the units must be later decoupled. The review shows that there are several excellent
click reactions and some of them such as azide alkyne addition or thiol addition to
unsaturated systems have been applied very successfully to the synthesis of various
large molecules including macromolecular units containing carbohydrates. Never-
theless, the field of decoupling is much less often visited, and thus, there is an acute
need for novel methods of decoupling. In addition, we hope that future availability
of a variety of sacrificial units will encourage chemists to take advantage of them.
It will enable much better assessment of what the limitations of specific decoupling
methods are. The area of research that should strongly benefit from such knowledge
is the sequencing of complex, natural polysaccharides.
REFERENCES
1. Bielski, R.; Witczak, Z. J.
Chem. Rev.
2012
. DOI: org/10.1021/cr200338q.
2. Brantley, J. N.; Wiggins, K. M.; Bielawski, C. W.
Science
2011
,
333
, 1606-1609.
3. Barner-Kowollik, C.; Du Prez, F. E.; Espeel, P.; Hawker, C. J.; Junkers, T.; Schlaad, H.;
Van Camp, W.
Angew.Chem.Int.Ed.
2010
,
50
, 60-62.
4. Aragao-Leoneti, V.; Campo, V. L.; Gomes, A. S.; Field, R. A.; Carvalho, I.
Tetrahedron
2010
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66
, 9475-9792.
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