Macrocyclic Ligands - Web del Profesor

8 MACROCYCLIC LIGANDS
PhAs As(Ph)Li
As(Ph)Li
+
Cl Cl
Scheme 7
PhAs
As
Ph
AsPh
Cryptands are usually synthesized via sequential condensations
between a diamine and an acid chloride, which
yields a diamide, followed by reduction with LiAlH4
to give the macromonocycle. Condensation with another
H2N O O NH2 O O
Cl O O Cl
HN
O O
O O
NH
HN
+
O O
Cl O O Cl
N
O O
O O
O O
O
O O
O
equivalent of acyl chloride will yield the bicyclic precursor,
which can be reduced by B2H6 to give the bicycle
(Scheme 8). 5
Compartmental ligands (16) are derived from diketonates
and triketonates and are usually synthesized from Schiff base
reactions of the ketone with a diamine. 28
Catenands (17) are also made using the metal ion template
effect. A bis-complex is formed from an α,α ′ -disubstituted
o-phenanthroline. Then the initial product is treated with a
diiodoalkane to accomplish the ring closure. 29
3.4 Polyoxa Macrocycles
Polyethers were originally synthesized by template
assistance from an oligo(ethylene glycol), monoglyme, and
potassium t-butoxide (Scheme 9). 4
O O
HN
NH
O O
O O
NH
N
O O
O
N
Scheme 8
O
O O
O
O
N
B2H 6
LAH