Photochromic [3H]naphtho[2,1-b]pyran...

Details Photochromic [3H]naphtho[2,1-b]pyran... Photochromic [3H]naphtho[2,1-b]pyran...

2000-02-29

2001-08-28

Dentz, Bernard (Department: 1625)

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

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

C549S214000, C549S389000, C524S109000, C524S110000

Reexamination Certificate

active

06281366

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to photochromic compounds, more particularly heterocyclic compounds of the [3H]naphtho[2,1-b]pyran family substituted with an acetylenic group, and to their application in the field of materials and articles with variable optical transmission.
BACKGROUND OF THE INVENTION
When photochromic compounds are subjected to irradiation containing ultraviolet rays (sunlight, xenon lamps or mercury lamps), they undergo a reversible color change. As soon as the excitation stops, they regain their original color.
In recent years, organic materials intended for optical applications have been the subject of considerable research. Ophthalmic glasses, glass for the construction industry, motor vehicle or airplane windshields and helmet visors, whose transparency in the visible range can be modified by using photochromic compounds, have particularly attracted attention. For this type of application using sunlight (heliochromism), the photochromic active compound must satisfy a certain number of criteria, among which are:
high colorability in the visible range after excitation with light (colorability is a measure of the capacity of a photochromic compound to exhibit an intense color);
an absence of coloration (or a weak coloration) in the initial state;
rapid kinetics of thermal decolozization at room temperature;
a high speed of coloration.
One of the major difficulties encountered with photochromic compounds is that of obtaining a compromise between high colorability and rapid decolorization kinetics. The reason for this is that, under continuous solar irradiation, a photostationary equilibrium is established between the molecules which become colored under the action of ultraviolet light and those which become decolorized under the conjugate action of temperature and visible light. Thus, frequently, an increase in the rate of decolorization entails a decrease in the colorability.
U.S. patent application Ser. No. 09/349,686 to Michel Frigoli et al, filed on Jul. 8, 1999 discloses a novel family of naphtho[2,1-b]pyrans substituted with bithienyl or terthienyl groups, which have particularly advantageous photochromic properties.
However, these novel naphtho[2,1-b]pyrans substituted with bithienyl or terthienyl groups, as well as the classical photochromic compounds of the naphtho[2,1-b]pyrans family, suffer of a lack of resistance to fatigue (also known as photodegradation of the photochromic compound).
In other words, the initial maximum colorability (Ao) of a photochromic compound decreases in time upon irradiation by visible light, and the resistance to fatigue of a photochromic compound is usually determined by measuring the time t for the colorability of the photochromic to decrease to a value equals to Ao/2 upon continuous irradiation by visible light. The longer is this time t the higher is the resistance to fatigue of the photochromic compound.
Thus, one object of the invention is to provide photochromic compounds having photochromic properties at least equivalent to those of the known photochromic compounds, in particular of the naphtho[2,1-b]pyrans family, but exhibiting significantly improved resistance to fatigue.
This combination of characteristics makes these novel compounds particularly advantageous for the manufacture of photochromic materials, in particular comprising a substrate made of transparent polymer material such as organic glasses with variable optical transmission (glass for sunglasses, glass for the construction industry, motor vehicle or airplane windshields, and riding or flying helmet visors).
The photochromic compounds can be incorporated directly into the organic glass substrate or dissolved in a polymer film stuck to the organic glass substrate.
SUMMARY OF THE INVENTION
The compounds which form the subject of the invention are [3H]naphtho[2,1-b]pyrans (I) bearing an acetylenic group on one of the positions 7 to 10, preferably position 8, of the naphto pyran ring structure.
DETAILED DESCRIPTION OF THE INVENTION AND PREFERRED EMBODIMENTS
A first class of the photochromic compounds according to the invention has formula:
in which Y is an acetylenic group directly linked to one of the 7 to 10 positions of the naphthopyran ring structure and R
1
and R
2
are, independently from each other, H, alkyl, cycloalkyl, aryl or heteroaryl.
Preferably Y has formula:
in which R is H, alkyl, cycloalkyl, aryl or heteroaryl.
Preferably alkyl groups for R are C
1
-C
6
alkyl groups, such as methyl, ethyl, propyl and butyl.
Preferred cycloalkyl groups are C
5
-C
7
cycloalkyl groups such as cyclopentyl, cyclohexyl and cycloheptyl.
Preferred aryl groups for R are phenyl, substituted phenyl groups, naphtyl and substituted naphtyl groups.
Preferred heteroaryl groups for R are thienyl and bithienyl groups.
The most preferred aryl groups for R are the groups of formula:
in which Z is H or an alkyl group, preferably a C
1
-C
6
alkyl group such as methyl, ethyl.
Among the preferred heteroaryl groups are those of formulas:
In which R
3
denotes H or a substituent which can occupy one of the position 2, 3, 3′, 4, 4′ and 5′. Preferably, R
3
as a substituent, occupies position 2 or 5′.
As a substituent, R
3
is selected from the group consisting of alkyl groups, cycloalkyl groups, aryl groups, —OR′, —SR′, —COR′ and —COOR′ in which R′ is H, an alkyl group, a cycloalkyl group, an aryl group, an amino group, —NO
2
, —CN, —SCN, a halogen atom or a mono- or polyhaloalkyl group.
Preferred alkyl groups for R
3
are C
1
-C
6
alkyl groups, such as methyl, ethyl, propyl, butyl and hexyl, preferred cycloalkyl groups are C
5
-C
7
cycloalkyl groups, such as cyclopentyl, cyclohexyl and cycloheptyl; preferred aryl groups are phenyl, a phenyl which is mono- or polysubstituted with one (or more) C
1
-C
6
alkyl, C
5
-C
7
cycloalkyl, phenyl and amino substituent(s); halogens preferably represent Br, Cl and F; and the mono- (or poly-) haloalkyl groups are preferably mono- (or poly)chloro or fluoro C
1
-C
6
alkyl groups, for example —CF
3
.
The most preferred heteroaryl groups are:
R
1
and R
2
which are identical or different, represent H, an alkyl group, preferably a C
1
-C
6
alkyl group such as methyl, ethyl, propyl, a cycloalkyl group, preferably a C
5
-C
7
cycloalkyl group, an aryl group, an heteroaryl group, a group —OR′, —SR′, —COR′ and COOR′, in which R′ is as above.
Preferred aryl groups for R
1
and R
2
are those of formula:
In which R
a
represents H, an alkyl group, an aryl group, a group —OR″, —SR″, —COR″ and COOR″, in which R″ is defined as R′ or is an amino group of formula NR
4
R
5
in which R
4
and R
5
represent, independently from each other, an alkyl group, a cycloalkyl group, an aryl group, R
4
and R
5
being capable to form with the nitrogen carbon atom, an aromatic heterocycle having 4 to 7 links and optionally including one or more heteroatoms selected from oxygen, nitrogen and sulfur, and n is an integer from 1 to 5.
Preferred heteroaryl groups for R
1
and R
2
are Th 1 and Th 2 groups defined above.
The compound of formula (I) can be synthetized by Csp2-Csp Sonogashira-Hagihara coupling. This coupling is disclosed in Tetrahedron Letters, 50, 4467 (1975) K Sonogashira, Y Thoda and N Hagihara and in Synthesis, 571 (1984) A Carpita, A Leni, R. Roni.
This synthesis of the photochromic compounds of the invention may be represented as follows:
The following synthesis are given only as illustration of the use of the Sonogashira-Hagihara coupling reaction for preparing photochromic compounds according to the present invention.
Synthesis of 8-(3-hydroxy-3-methylbut-1-yn-1-yl)-3-3-diphenyl-[3H]-naphtho[2,1-b]pyran
Catalysts: Copper (I) Iodide (Cu I)/bis[trisphenylphosphine]palladium (II) dichloride (Pd(PPh
3
)
2
Cl
2
).
Solvent: (C
2
H
5
)
2
NH.
Synthesis of preferred compounds of formulas
These compound

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