Books
in black and white
Main menu
Share a book About us Home
Books
Biology Business Chemistry Computers Culture Economics Fiction Games Guide History Management Mathematical Medicine Mental Fitnes Physics Psychology Scince Sport Technics
Ads

The porphyrin handbook - Kadish K.M.

Kadish K.M. The porphyrin handbook - Academic press, 2000. - 368 p.
Download (direct link): kadishsmishgulilard2000.djvu
Previous << 1 .. 177 178 179 180 181 182 < 183 > 184 185 186 187 188 189 .. 240 >> Next

of calix[3]-indoles with only hydrogen atoms on the linking carbon atoms
were consistent with the indole rings being fluxional. However, they also
found: (I) that when aryl groups are attached to the linking carbon
atoms, the conformational
the Cambridge Crystallographic Database.
Figure 29. The X-ray crystal structure of calix[3Jindole 26a. Crystal
structure originally published in Black, D. S.; Craig, D. C.; Kumar, N.
Tetrahedron Lett. 1995, 36, 8075. Diagram produced using data from the
Cambridge Crystallographic Database.
Figure 30. The X-ray crystal structure of 27(cone). Crystal structure
originally published in Black, D. S.; Craig, D. C.; Kumar, N.; McConnell,
D. B. Tetrahedron Lett. 1996, 37, 241. Diagram produced using data from
the Cambridge Crystallographic Database.
flexibility of the calix[3]pyrrole is reduced; and (2) that all three of
the indole rings are in different magnetic environments (as judged by 'H
NMR analyses). Black et al. reasoned that by attaching three axial-
orienting hydrogen-bonding groups to the linking carbon atoms, they would
be able to stabilize the cone conformation.''11 The most successful
embodiment of this strategy is a calix|31-indole containing three tert-
butyl amide substituents 27 (Figure 30). The cone conformer was isolated
in 17% yield and the flattened partial cone was isolated in 45% yield.
276
Sessler and Gale
OMe
MeO'

H*-4C
RHNOC'
MeO'
H~C OMe RHNOC"
C," Ar 'CONHR

OMe
27(cone)
Ar := C6H4-p-CI R - CM03
C" Ar {TCONHR

OMe

27 (flattened partial cone) Ar = C6H4-p-CI R = CMe3
Scheme 4. Synthesis of [14]azolophanes via a [3 + 1] convergent stepwise
synthesis.

/

N-N

28a-c

H
N-N

30
dry CH3CN reflux, ca. 48h

H
NirN
31a (42%), 31b (40%), 31c (51%)
,x(r)> <(r)x
H
ion exchange III resin OH'form

N- N
hpf6-h2o
to pH 3-4
{>90%)
32a (55%), NAN 32b (60%),
32c (30%)
ion exchange III resin OH'form
1 tc
N~N 33a-c

hpf6-h2o

to pH 6-7 t (> 85%)
N-N
1 1
33a, 31a. 28a R = H 33b, 31b, 28b: R = Me 33c, 31c, 28c. R = Bu 34a.
32a, 29a: R = H, R' = Me 34b, 32b, 29b- R = H R'= Bu 34c. 32c, 29c R =
Me, R' = Me
Ny-N

H
35a-c
The X-ray crystal structure of 27(cone) confirmed that the
calixindole adopts a cone conformation with a hydrogen-bonded array of
axial groups at the lower rim of the calixindole. Interestingly an
ethanol molecule (not shown) is bound within the cup-shaped cavity of the
molecule (Figure 30).
An interesting account of the attempted use of group-V elements as
templates for the formation of calix[3Jindoles in the cone conformation
has also been published.91
Figure 31. The X-ray Crystal Structure of 34a 4H20. Crystal structure
originally published in Alcalde, E.; Gisbert, .; Alvarez-Rua, C.;
Garcfa-Granda, S. Tetrahedron 1996, 52, 15189. Diagram produced using
Previous << 1 .. 177 178 179 180 181 182 < 183 > 184 185 186 187 188 189 .. 240 >> Next