Chemistry Reference
In-Depth Information
in pyridine at room temperature [
40
,
41
]. A more soluble derivative of CuTCPH (
11
)
containing four hydroxy substituents at the
meta
-positions of the
meso
-phenyl groups
was prepared in about 30% yield using similar condensation and metallation
conditions [
39
]. The resulting tetrahydroxy-CuTCPH was obtained by dealkylation
of the corresponding tetramethoxyporphyrin using BBr
3
.
Using Lindsey's condensation conditions, H
2
TCP
13
in both
10
B-enriched and
non-enriched forms were synthesized by condensation of pyrrole with
para
(
ortho
-
carboranyl)benzaldehyde using BF
3
·OEt
2
as catalyst, followed by oxidation with
DDQ and deboronation with pyridine/piperidine 3:1, in about 50% yield [
26
,
29
,
42
-
44
]. An alternative but low-yielding reported synthesis of this porphyrin involves
the functionalization of a pre-formed tetra(4-iodophenyl)porphyrin with
ortho
-
carborane via Cu(I)-catalyzed coupling [
45
]. The tetrabenzo-carboranylporphyrin
14
was prepared by condensation of tetrahydroisoindole with
para
(
ortho
-carboranyl)
benzaldehyde under Lindsey's conditions, followed by metallation with CuCl
2
,
oxidation to tetrabenzoporphyrin using excess DDQ, demetallation with conc.
H
2
SO
4
, and final deboronation of the
ortho
-carboranes using tetrabutylammonium
fluoride in THF, in about 30% overall yield [
46
,
47
].
The octa-
ortho
-carboranylporphyrin
15
of high boron content was synthesized in
about 10% yield from condensation of pyrrole with bis[3,5-(methyl-
ortho
-
carboranyl)methyl]benzaldehyde using TFA as the acid catalyst, followed by
oxidation with
para
-chloranil and deboronation of the
ortho
-carborane cages [
26
,
48
,
49
].
meso
-Tetraaryl-carboranylporphyrins
16
and
17
bearing carborane cages on the
ʲ
-pyrrolic positions of the macrocycle have been synthesized from carboranyl-
pyrroles and aldehydes under Lindsey's conditions, in 49% and 20% yields,
respectively [
50
,
51
]. Condensation of the boronated pyrrole with benzaldehyde,
