Conformationally constrained compounds as dendrimer cores

Details Conformationally constrained compounds as dendrimer cores Conformationally constrained compounds as dendrimer cores

2002-02-11

2004-03-09

Kumar, Shailendra (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Four or more ring nitrogens in the bicyclo ring system

C546S026000, C546S184000, C548S301700, C568S579000, C568S585000, C568S631000, C568S633000

Reexamination Certificate

active

06703504

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to novel chemical compounds and their uses in the preparation of polymers and oligomers, and the preparation of such compounds. It also relates to polymers and oligomers prepared using such compounds, and processes for the preparation of the polymers and oligomers. More particularly, this invention relates to dendritic polymers and oligomers, of the type having at least four polymeric or oligomeric organic chains emanating from a single chemical core, each of the chains being of substantially equal length and substantially the same chemical composition. Such dendritic polymers and oligomers are referred to herein, for convenience, as dendrimers.
BACKGROUND OF THE INVENTION AND PRIOR ART
Dendrimers as defined above are known chemical entities. Practitioners of the chemical arts of dendrimers can recognize a core substructure to which the polymeric/oligomeric chains (“dendrons”) are covalently attached and from which they extend with systematic branching radially outward in a three dimensional fashion, to approximately the same extent as each other. Together, core and dendrons constitute macromolecules possessing a high degree of internal structural replication attributable to the branches. The symmetry, partial symmetry or asymmetry of the dendrimer is a partial reflection of the impact of the core. Because of the influence of both core and branches, the chemical end groups of the chains are disposed on the surface of the macromolecules. All together, core, dendrons and surface functionalities determine the properties of the polymer. Accordingly a wide variety of such materials can be prepared with different but predetermined size and shape characteristics and different but predetermined chemical surface characteristics, useful in a variety of different practical applications (chromatographic supports, catalytic supports, synthetic membranes, for example). A review of dendrimers of this type, their preparation, properties, characteristics and uses, is found in
Angew. Chem. Int. Ed. Engl
. (1990), 29, 138, authored by Tomalia, Donald A., Naylor, Adel M., and Goddard III, William A. The disclosure of that review is incorporated herein in its entirety.
An important feature in determining the final characteristics of such a dendrimer is the choice of core chemical entity and its properties. Some of these properties have been noted in the prior art, others have not. Among the various properties which such a core entity could beneficially possess are:
a high degree of conformational rigidity, so that each dendron may start from a point in space more or less specifically defined with respect to the starting points of other dendrons. The shape, in three dimensional space of the polyhedron, defined by the starting positions of the functional groups from which the dendrons eventually protrude, is in this way a characteristic property of a core. If the dendrons are flexible but the dendrimer is to have some substantial element of controlled shape, that shape is largely dictated by the rigid core;
a large number of identical functionalities to which the dendrons may be attached. This will reduce the number of generations before the dendrimer surface assumes an essential spherical shape covered by a large number of surface reactive groups;
core functionalities sterically well separated, to reduce the likelihood of intramolecular branch defects; and
an overall low symmetry and chirality, so that in cases where the dendrimer is to be used in a natural biological environment, the dendrimer will more closely mimic such environment.
Many different compounds have been proposed in the prior art, for use as the core entity of such dendrimers. The aforementioned article of Tomalia et. al. discloses ammonia, amines, linear polyethyleneimines, polyethylene glycols and a number of others. More complex cores, including chiral cores, have also been used. The range of possible candidates is very broad. Jason M. Rohde and Jon R. Parquette, in “Synthesis of dendrimers containing 2,5-anhydro-D-mannitol as chiral tetra-functional central core with C2 symmetry”,
Tetrahedron Letters
(1998), 39, 9161 disclose the use of 1,3,4,6-tetra-O-(4-hydroxybenzoyl)-2,5-anhydro-D-mannitol as core for a dendrimer. Whilst an advance over small molecular cores, this compound still exhibits too much rotatidnal flexibility in its bonds and is thus capable of assuming too many conformations. The desirability of providing more rigid dendrimer cores, to obtain more extensive conformational order in the polymers, has recently been acknowledged by Weintraub et. al. in “Synthesis and chiroptical properties of amphiphilic dendrimers based on 2,3-dihydroxybenzyl alcohol”,
Tetrahedron
(2001), 57, 9393.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide novel chemical entities useful as core entities in the preparation of dendrimers.
It is a further object of the invention to provide novel dendrimers based on the novel chemical entities.
The present invention, from one aspect provides novel chemical entities useful as core entities in dendrimers and corresponding to the following general chemical structure Q.
Wherein:
at least one of the W and W
1
groups on a given phenyl ring is independently an electron-donating functionality and the other is independently selected from hydrogen and a bond of a fused rigid mono or polycyclic carbocyclic or N-heterocyclic ring involving either Z or an adjacent substituent R;
Z is either hydrogen or together with an adjacent substituent W or W
1
, forms a fused rigid ring as aforesaid;
R
1
and R
2
are independently selected from hydrogen, a non-interfering chemical group, and a bond of a fused rigid mono or polycyclic carbocyclic or N-heterocyclic ring involving an adjacent substituent W on the same phenyl ring; or together represent a first bridge joining the respective carbon atoms to which each R
1
and R
2
is attached, said first bridge being selected from direct bond and —(CH
2
)—;
T-butyl, chloro, bromo, iodo, alkylthio, halogen substituted methyl, lower alkoxy substituted methyl, lower alkylthio substituted methyl.
R
3
is selected from hydrogen, a non-interfering chemical group and a bond of a fused rigid mono or polycyclic carbocyclic or N-heterocyclic ring involving an adjacent substituent W
1
, or R
3
forms a second bridge with R
4
, said bridge joining the respective carbon atoms to which each R
3
and R
4
is attached and said second bridge being selected from direct bond, —(C═O)—, —(CH
2
)— and —(CHOH)—;
R
4
is either hydrogen or together with R
3
, forms the aforesaid second bridge, with the proviso that R
1
and R
2
do not form a bridge when R
3
and R
4
form a bridge;
R
5
is either hydrogen or together with R
6
forms a third bridge, said bridge joining the respective carbon atoms to which each R
5
and R
6
is attached and said third bridge being selected from, —(C═O), —(CH
2
)— and —(CHOH)—;
R
6
is selected from hydrogen, a non-interfering chemical group and a bond of a fused rigid mono or polycyclic carbocyclic or N-heterocyclic ring involving an adjacent substituent W
1
, or together with R
5
forms the aforesaid third bridge;
R
7
is selected from hydrogen, a non-interfering chemical group and a bond of a fused rigid mono or polycyclic carbocyclic or N-heterocyclic ring involving an adjacent substituent W
1
;
R
8
is selected from hydrogen, a non-interfering chemical group and a bond of a fused rigid mono or polycyclic carbocyclic or N-heterocyclic ring involving an adjacent substituent W; and
R
9
is selected from hydrogen, a non-interfering chemical group and a bond of a fused rigid mono or polycyclic carbocyclic or N-heterocyclic ring involving an adjacent substituent W
1
.
Such a chemical entity provides a number of features, which in combination lead to the formation of highly desirable dendrimers based thereon. One such feature is the substantial orientational rigidity of aromatic rings with respect to the central indane (benzocyclopentane) moiety. The indane system is itself capa

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