“SWEET” SUCROSE MACROCYCLES VIA A “CLICK CHEMISTRY” ROUTE - Click Chemistry in Glycoscience: New Developments and Strategies - page 236

Bn

N N

N

Bn

Bn Bn

Bn

(+)

N

N

NH 3

O O

OBn

OBn

Ph

O

O

O

BnO

O

ammonium
cation

BnO

OBn

OBn

O

O

BnO

OBn

BnO

OBn

OBn

OBn

29

30

K a = 1250 (for S-amine)
850 (for R-amine)

K a = 950 (for S-amine)
~0 (for R-amine)

FIGURE 9.11 Complexation of phenylethylammonium cation by sucrose macrocycles.

high-dilution [44], high-pressure techniques [45], metal-templated synthesis of crown
ethers [46], or metal-templated macrocyclizations [47].
The sucrose azidoacetylene 33 —chosen as starting material—was prepared read-
ily taking advantage of the very high affinity of the “fructose end” (C-6 )toward
silylation (Fig. 9.12) [48].

OH

HO

6'

regioselective
protection at
the fructose end

6

OBn

O

O

BnO

end (6') as
TBS ether

OBn

O

BnO

OBn

OBn

31

OH

TBSO

6

N 3

6'

O

6

Gluc Fruc

6'

Gluc Fruc

32

33

FIGURE 9.12 Preparation of the sucrose azido-acetylene for the synthesis of dimeric
sucroses by click approach.