PHOTOCHROMIC SUBSTITUTED 2H-NAPHTHO[1,2-b]PYRANS

Abstract: A 2H-naphtho[1,2-b]pyran of general formula (I) wherein R<5> is substituted and where R<8> is selected from the substituents including hydrogen, linear or branched C1-C20 alkyl, C3-C20 cycloalkyl, C4-C20 bicycloalkyl, C5-C20 polycycloalkyl, linear or branched C1-C20 haloalkyl, linear or branched C1-C20 perhaloalkyl, linear or branched C2-C20 alkenyl, linear or branched C4-C20 polyalkenyl, linear or branched C2-C20 alkynyl, linear or branched C4-C20 polyalkynyl, linear or branched C1-C20 hydroxyalkyl, linear or branched C1-C20 alkylcarbonyl, linear or branched C1-C20 polyhydroxyalkyl, linear or branched C1-C20 alkoxy, linear of branched C1-C20 alkylthio, linear or branched C1-C20(C1-C5 or C1-C10alkoxy)alkyl, linear or branched C1-C20(C1-C5 or C1-C10alkylthio)alkyl, benzoyl, aroyl, heteraroyl, phenyl, aryl, heteroaryl, halogen, hydroxyl, formyl, acetyl, linear or branched C3-C20 alkenoyl, linear or branched C5-C20 polyalkenoyl, nitrile, carboxyl, C1-C20 or C1-C5 alkoxycarbonyl, C1-C20 N-alkylamido, C1-C20 or C1-C5 N, N-dialkylamido, amido, nitro, amino, C1-C20 or C1-C5 alkylamino, C1-C20 dialkylamino, C2-C20 dialkenylamino, C4-C20di(polyalkenyl)amino, arylamino, diarylamino, C1-C20 alkylarylamino, cyclic-amino groups, arylsulfanyl, aryloxy, arylsulfinyl, arylsulfonyl, linear or branched C1-C20 alkylsulfonyl, and di-(C1-C10 or C1-C20 alkoxyalkyl)phosphonyl and X includes O, S, NH, or the function R<8>X is selected from aziridino, mono- or poly- substituted linear or branched C1-C20 alkyl aziridino, pyrrolidino, mono- or poly- substituted linear or branched C1-C20 alkyo pyrrolidino, piperidino, mono- or poly- substituted linear or branched C1-C20 alkyl piperidino, morpholino, mono- or poly- substituted linear or branched C1-C20 alkyl morpholino, thiomorpholino, mono- or poly- substituted linear or branched C1-C20 alkyl thiomorpholino, indolino, mono- or poly- substituted linear or branched C1-C20 alkyl indolino, piperazino, mono- or poly- substituted linear or branched C1-C20 alkyl piperazino, linear or branched C1-C20N-alkylpiperazino, linear or branched C1-C20N-hydroxyalkylpiperazino, N-phenylpiperazino, N-aryliperazino, homopiperidino, mono- or poly- substituted linear or branched C1-C20 alkyl homopiperidino, N-indolinyl, N-1,2,3,4-tetrahydroquinolinyl, N-1,2,3,4,4a-hexahydrocarbazolyl. The compounds may be combined with polymeric host material such as plastic or glass or make a sunglass lens, an ophthalmic lens or a window. The compounds may also be included in an ink or a fuel.

Description: PH0T0CHR0MIC SUBSTITUTED 2H-NAPHTH0[1 ,2-B]PYRANS The present invention relates to certain new photochromic naphthopyrans and their use. Photochromism is a well established physical phenomenon which is observed with certain classes of chemical compounds. A detailed discussion of this phenomenon can be found in 'Photochromism: Molecules and Systems,' Studies in Organic Chemistry 40, eds. H. Durr and H. Bouas-Laurent, Elsevier, 1990. The 2H-naphtho[l,2-b]pyran system (see structure below) is known to be capable of exerting a photochromic effect as described, for example, in US Patent No. 3,567,605 and US Patent No. 4,826,977. The former provides an example of a 2H-naphtho[l,2- b]pyran that remains coloured at ambient temperatures for several hours and the latter describes a series of yellow/orange colouring 2H-naphtho[l,2-b]pyrans that have a spiro-adamantane group at C-2. A range of purple/blue colouring 2-alkyl-2(4-aminophenyl)-2H-naphtho[l,2-b]pyrans have been described in US Patent No. 4,818,096 and European Patent No. 0,250,193 describes a range of photochromic naphthopyrans which bear one or two 4-aminophenyl substituents on the carbon atom adjacent to the oxygen heteroatom. In this patent it is stated that substitution in the ring positions, sites 5 - 10, other than site 6 has little influence on the photochromic behaviour of the compounds. ' A series of 2H-naphtho[l,2-b]pyrans amongst other isomeric naphthopyrans, bearing a cyclopropyl group as one of the substituents at the 2-position is described in patent publication WO92/01959. It is also commented that the compound 2-cyclopropyl-2- (4-methoxyphenyl)-5-methyl-2H-naphtho[l,2-b]pyran and several other analogues are of particular current interest, but no reasons are presented to substantiate such interest or as to any significance of the 5-methyl group. It is stated in US Patent No. 5,066,818 (1991) that 'The compound, 2,2-diphenyl-2H- naphtho[l,2-b]pyran, also colours on exposure to near ultraviolet light at room temperature but does not bleach in a reasonable period of time. Substitution of the phenyl substituents in the meta and para positions have little effect on the rate of bleaching of these compounds." The very high optical density of 2,2-diaryl-2H-naphtho[l,2-b]pyrans achieved under irradiation and their slow attendant fade (bleaching) on removal of the source of irradiation relative to the photochromic properties displayed by the isomeric 3,3- diaryl-3H-naphtho[2,l-b]pyrans has been recently noted by B. van Gemert et al. (Mol. Cryst. Liq. Cryst., 1994, 246, 67) The relatively slow attendant fade of the 2,2- diaryl-2H-naphtho[l,2-b]pyrans was rationalised by the absence of steric crowding in the ring opened (coloured) quinoidal/zwitterionic forms Such steric crowding is thought to be present for the ring opened form of the 3,3-diaryl-3H-naphtho[2,l- bjpyrans and accounts for their relatively rapid fade Pilkington PLC have commented on the control of fading of 2H-naphtho[l,2-ό]pyrans in Research Disclosure May ( 1994), No 36144, p 267 In this disclosure the presence of methyl groups at the 5- and 6-positions of some 2,2-diaryl-2H-naphtho[l,2- b]pyrans proved beneficial to the photochromic response of the molecules compared to molecules without such methyl substituents The 5-substituent introduces steric crowding so mimicking the situation in the isomeric naphtho[2, l-b]pyrans Some recent US Patents No 5,458,814, No 5,514,817, No 5,651,923 and No. 5,656,206 and an international application PCT WO 98/04937 have capitalised on this disclosure and claim a range of 'fast fading' intense colouring 5-substituted and 5,6- disubstituted 2,2-diaryl-2H-naphtho[l,2-b]pyrans and some benzologues The latter application PCT WO 98/04937 claims 5-substituted 2,2-diaryl-2H-naphtho[l,2- b]pyrans which have alkoxy substituents in the 7- and 9-positions and are said to shift λ max to a longer wavelength with only some examples exhibiting a higher induced optical density We have investigated the above known class of photochromic compounds (2,2-diaryl- 2H-naphtho[l,2-b]pyrans) and have found that when a 5-substituent is present to give acceptable fade rates at ambient temperatures, enhanced intense colour generation can be achieved by placing an electron-releasing group at position 8. This effect is accompanied by a small decrease in the rate of fade, a feature that is particularly beneficial when the compounds are to be used for ophthalmic purposes. We have also discovered that this effect may be further augmented by the presence of an additional electron-releasing group at position 7 or at position 10 or at positions 7 and 10. This phenomenon provides photochromic materials with acceptable rates of fade over a broad range of ambient temperatures and intense colour generation accompanied by negligible background colour. These features render these compounds particularly useful as photochromic materials for incorporation into polymeric host materials since the amount of photochromic material required to impart a useful photochromic effect into the host material may be greatly reduced, thereby offering a considerable saving of synthetic effort and cost over conventional materials which do not possess the claimed substituents. Furthermore, we have discovered that the intensity of the generated colour observed when photochromic 2,2-diaryl-2H-naphtho[l,2-b]pyrans, which possess a 5- substituent to give acceptable fade rates at ambient temperatures, are irradiated can be diminished by placing electron releasing substituents at position 9 or at position 7. This reduction of intensity of the generated colour is typically accompanied by a small increase in the rate of fade of the said colour and provides photochromic materials with acceptable rates of fade over a broad range of ambient temperatures. Examples of applications of the polymeric host materials of the present invention include the manufacture of lenses for sunglasses and ophthalmic lenses, protective visors, screens, films, 'plastic' sheeting, containers (e.g. bottles and other packaging vessels), mirrors, windows and screens for vehicles such as cars (including sunroofs), motorcycles, aircraft and ships, architectural uses e g. glazing, and artistic 'stained glass' windows and for use in novelty items. Additionally the materials may be used in vehicle body panels including fairings and spoilers, and related external surfaces and other embodiments where it may be deemed attractive to have said objects change colour in the presence of sunlight. A further use is their incorporation into inks and other such formulations for 'printing' onto paper and fabrics and other suitable surfaces. This latter application may be particularly useful for the preparation of security markers (labels) on a broad range of objects e.g. cheques, bonds, bankers drafts, credit cards, charge cards and identity documents and cards. Such inks and other like formulations may be used for printing documents and greetings cards. The security / identity uses of these photochromic compounds may also extend to include the marking of fuels e.g. petrol and diesel and other oils. Furthermore, the materials may be used in optical data recording systems e.g. compact discs, and read / write optical data storage discs, as waveguides and laser dyes. Typical host materials are optically clear or opaque polymer materials, such as polymers of polyol (allyl carbonate) - monomers, polyacrylates such as polymethylmethacrylates, poly(triethyleneglycol dimethylacrylate), polyp erfluoro- acrylates and cellulose acetate, cellulose triacetate, cellulose acetate propionate, cellulose acetate butyrate, poly(vinyl acetate), poly(vinyl alcohol), polyurethanes, polycarbonate, polyethylene terephthalate, polystyrene, polyperfluorostyrene, poly(diethyleneglycol bis(allyl carbonate)) and various copolymer mixes. According to the present invention, there is provided a photochromic 2H-naphtho[l,2- b]pyran of the formula (I) In formula (I) above R and or R , which may be the same or different, are each selected from phenyl, mono-, di- or poly- substituted aryl groups, unsubstituted, mono-, di- or poly- substituted naphthyl groups and unsubstituted, mono-, di- or poly- substituted heteroaryl groups (for example but not exclusively thienyl, benzothienyl, furyl, benzofuryl, pyrryl, indolyl, pyridyL quinolyl, isoquinolyl, pyrimidyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyL, pyrazolyl, imidazolyl, benzimidazolyl, triazolyl, benzotriazolyl, tetrazolyl). The substituents for the aryl, naphthyl and heteroaryl groups representing R 1 and R 2 may be linear or branched C1-C20 alkyl, C3-C20 cycloalkyl, C -C 2 o bicycloalkyl (for example but not exclusively norbornyl), C5-C20 polycycloalkyl (for example but not exclusively adamantyl), linear or branched C1-C20 haloalkyl, linear or branched C1-C20 perhaloalkyl, linear or branched C2-C20 alkenyl (E or Z isomers), linear or branched C -C20 polyalkenyl (any combinations of E or Z isomers), linear or branched C2-C 2 0 alkynyl, linear or branched C -Q2o polyalkynyl, linear or branched C 1 -C20 hydroxyalkyl, linear or branched C ! -C2o polyhydroxyalkyl, linear or branched C 1 -C20 alkoxy, linear or branched C 1 -C2 0 alkylthio, linear or branched Cι-C o(C ! -Cιo alkoxy)alkyl, linear or branched Ci-C 2 o(Ci-C alkylthio)alkyl, phenyl, aryl, heteroaryl, halogen, hydroxyl, formyl, acetyl, linear or branched C3-C20 alkenoyl, linear or branched C5-C20 polyalkenoyl, nitrile, carboxyl, C!-C o alkox carbonyl, C 1 -C20 N-alkylamido, C1-C20 NN-dialkylamido, amido, nitro, a ino, C1-C20 alkylamino, C1-C20 dialkylamino, C2-C20 dialkenylamino, C -C 2 o di(polyalkenyl)amino, arylamino, diarylamino, C 1 -C 2 0 alkylarylamino, and cyclic- amino groups (for example but not exclusively aziridino, pyrrolidino, piperidino, hoπfopiperidino, morpholino, thiomorpholino, indolino, piperazino, linear or branched C 1 -C 10 N-alkylpiperazino, linear or branched C 1 -C 20 N-hydroxya kylpiperazino, N- phenylp'iperazino, N-arylpiperazino, homopiperidino), arylsulfanyl, aryloxy, arylsulfinyl, arylsulfonyl, linear or branched C1-C2G alkylsulfonyl, di-(Cι-Cιo alkoxy alkyl)phosphonyl. Phenyl, aryl, naphthyl, and heteroaryl ring substituents may be located at the ortho-, meta- or para- positions. Typically each aryl group contains less than 3 substituents. R 1 and or R 2 may also be selected from the fused saturated heterocycles II, DI and IV in which n and m are integers between 2 and 5 and may be the same or different. IV R π may be selected from linear or branched C1-C 20 alkyl, C 3 -C 2 o cycloalkyl, C -C 2 o bicycloalkyl, C5-C20 polycycloalkyl, linear or branched C 1 -C 20 hydroxyalkyl, linear or branched C1-C20 haloalkyl, linear or branched C 1 -C 20 perhaloalkyl, phenyl, C 1 -C 20 linear or branched alkylsulfonyl, aryl, tosyL, arylsulfonyl, acyl, linear or branched C1-C20 alkylcarbonyl, benzoyl, aroyl, substituted aroyl, butoxycarbonyl. R 3 and R 4 , which may be the same or different, are selected from hydrogen, linear or branched Ct-Q-o alkyl, C 3 -C2o cycloalkyl, C -C2o bicycloalkyl (for example but not exclusively norbornyl), C5-C20 polycycloalkyl (for example but not exclusively adamantyl), linear or branched C1-C 20 haloalkyl, linear or branched Ct- C 20 perhaloalkyl, linear or branched C2-C20 alkenyl (E or Z isomers), linear or branched C -C2o polyalkenyl (any combination of E or Z isomers), linear or branched C 2 -C20 alkynyl, linear or branched -C20 polyalkynyl, linear or branched C1-C20 hydroxyalkyl, linear or branched Cι-C 2 o polyhydroxyalkyl, linear or branched alkoxy, linear or branched C1-C20 alkylthio, linear or branched alkoxy)alkyl, linear or branched Cι-C 2 o(Cι-C5 alkylthio)alkyl, phenyl, aryl, heteroaryl, halogen, hydroxyl, formyl, acetyl, linear or branched C 3 -C 2 o alkenoyl, linear or branched C5-C2 0 polyalkenoyl, nitrile, carboxyl, C 1 -C 5 alkoxycarbonyl, C^Cs N- alkylamido, C 1 -C 5 NN-dialkylamido, amido, nitro, in addition to those groups specified for R and R above. R 5 is selected 7 from linear or branched Cϋ-C2o alkyl, C 3 -C 2 0 cycloalkyl, C -C20 bicycloalkyl (for example but not exclusively norbornyl), C 5 -C 20 polycycloalkyl (for example but not exclusively adamantyl), linear or branched C 1 -C 20 haloalkyl, linear or branched C1-C20 perhaloalkyl, linear or branched C2-C20 alkenyl (E or Z isomers), linear or branched C -C 2 o polyalkenyl (any combination of E or Z isomers), linear or branched C2-C20 alkynyl, linear or branched C4-Q20 polyalkynyl, linear or branched d-C2o hydroxyalkyl, linear or branched C1-C20 polyhydroxyalkyl, linear or branched C 1 -C20 alkoxy, linear or branched C1-C20 alkylthio, linear or branched Cι-C 2 o(Cι-C5 alkoxy)alkyl, linear or branched Cι-C2o(Cι-C 5 alkylthio)alkyl, phenyl, aryl, heteroaryl, halogen, hydroxyl, formyl, acetyl, linear or branched C 1 -C 20 alkylcarbonyl, linear or branched C3-C20 alkenoyl, linear or branched C5-C 20 polyalkenoyl, benzoyl, aroyl, heteroaroyl, nitrile, carboxyl, C1-C20 alkoxycarbonyl, Ct-C ∑ o N-alkylamido, C1-C20 N-N-dialkylamido, amido, nitro, amino, C1-C20 alkylamino, C 1 -C20 dialkylamino, C2- C 20 dialkenylamino, C 4 -C20 di(polyalkenyl)amino, arylamino, diarylamino, C1-C20 alkylarylamino, and cyclic-amino groups (for example but not exclusively aziridino, pyrrolidino, piperidino, morpholino, homopiperidino, thiomorpholino, indolino, piperazino, linear or branched C1-C20 N-alkylpiperazino, linear or branched C 1 -C 2G N- hydroxyalkylpiperazino, N-phenylpiperazino, N-arylpiperazino, homopiperidino, N- indolinyl), arylsulfanyl, aryloxy, arylsulfinyl, arylsulfonyl, linear or branched C 1 -C 2 Q alkylsulfonyl, di-(Cι-C 2 o alkoxyalkyl)phosphonyl in addition to those substituents specified for R 1 and R . R and R which may be the same or different, are selected from hydrogen, linear or branched C1-C20 alkyl, C3-C20 cycloalkyl, C 4 -C 20 bicycloalkyl (for example but not exclusively norbornyl), C5-C20 polycycloalkyl (for example but not exclusively adamantyl), linear or branched C1-C20 haloalkyl, linear or branched Ci- C20 perhaloalkyl, linear or branched C2-C 20 alkenyl (E or Z isomers), linear or branched C4-C20 polyalkenyl (any combination of E or Z isomers), linear or branched C 2 -C20 alkynyl, linear or branched C -C2o polyalkynyl, linear or branched C1-C20 hydroxyalkyl, linear or branched C1-C20 polyhydroxyalkyl, linear or branched C1-C20 alkoxy, linear or branched Q-C20 alkylthio, linear or branched Ci-C o(Ci-Cs alkoxy)alkyl, linear or branched Cι-C2θ(Cι.-Cιo alkylthio)alkyl, phenyl, aryl, heteroaryl, halogen, hydroxyl, C1-C20 N-alkylamido, C 1 -C 20 NN-dialkyl amido, amino, C1-C20 alkylamino, C1-C20 dialkylamino, C2-C20 dialkenylamino, C4-C20 di(polyalkenyl)amino, arylamino, diarylamino, C 1 -C 20 alkylarylamino, and cyclic- amino groups (for example but not exclusively aziridino, pyrrolidino, piperidino, homopiperidino, morpholino, thiomorpholino, indolino, piperazino, linear or branched C1-C20 N-alkylpiperazino, linear or branched d-C 2 o N-hydroxyalkylpiperazino, N- phenylpiperazino, N-arylpiperazino, homopiperidino, N-indolinyl), arylsulfanyl, aryloxy. R δ , R 8 , R 9 , R u , R 12 , R 14 and R 15 which may be the same or different, are selected from hydrogen, linear or branched C 1 -C 2 0 alkyl, C 3 -C 20 cycloalkyl, C -C2o bicycloalkyl (for example but not exclusively norbornyl), C 5 -C 20 polycycloalkyl (for example but not exclusively adamantyl), linear or branched C 1 -C 20 haloalkyl, linear or branched C1-C20 perhaloalkyl, linear or branched C2-C 2 0 alkenyl (E or Z isomers), linear or branched C4-C20 polyalkenyl (any combination of E or Z isomers), linear or branched C2-C20 alkynyl, linear or branched -C20 polyalkynyl, linear or branched C1-C20 hydroxyalkyl, linear or branched C 1 -C2o polyhydroxyalkyl, linear or branched C1-C20 alkoxy, linear or branched C C2o alkylthio, linear or branched Cι-C2o(Cι-C5 alkσxy)alkyl, linear or branched Cι-C2o(Cι-Cιo alkylthio)alkyl, phenyl, aryl, heteroaryl, halogen, hydroxyl, formyl, acetyl, linear or branched C 1 -C 20 alkylcarbonyl, linear or branched C3-C2Q alkenoyl, linear or branched C 5 -C 2 0 polyalkenoyl, benzoyl, aroyl, heteroaroyl, nitrile, carboxyl, C1-C20 alkoxycarbonyl, C C 2 o N-alkylamido, Ci- C 2 o NN-dialkylamido, amido, nitro, amino, C1-C20 alkylamino, C 1 -C20 dialkylamino, C2-C20 dialkenylamino, C4-C20 di(polyalkenyl)amino, arylamino, diarylamino, C1-C20 alkylarylamino, and cyclic-amino groups (for example but not exclusively aziridino, pyrrolidino, piperidino, homopiperidino, morpholino, thiomorpholino, indolino, piperazino, linear or branched C1-C20 N-alkylpiperazino, linear or branched C1-C20 N- hydroxyalkylpiperazino, N-phenylpiperazino, N-arylpiperazino, homopiperidino, N- indolinyl), arylsulfanyl, aryloxy, arylsulfinyl, arylsulfonyl, linear or branched C1-C20 alkylsulfonyl, di-(Cι-Cιo alkoxyalkyl)phosphonyl in addition to those substituents specified for R 1 and R 2 and R 5 . R 16 of which there may be one or more, the same or different, are selected from hydrogen, linear or branched C 1 -C 20 alkyl, C3-C20 cycloalkyl, C4-C20 bicycloalkyl (for example but not exclusively norbornyl), C 5 -C 20 polycycloalkyl (for example but not exclusively adamantyl), linear or branched C 1 -C 2 0 haloalkyl, linear or branched C1-C20 perhaloalkyl, linear or branched C 2 -C 2 0 alkenyl (E or Z isomers), linear or branched C4-C20 polyalkenyl (any combination of E or Z isomers), linear or branched C 2 -C 2 o alkynyl, linear or branched C4-C 20 polyalkynyl, linear or branched Ci-C 20 hydroxyalkyl, linear or branched Cι-C 20 polyhydroxyalkyl, linear or branched C1-C20 alkoxy, linear or branched C1-C20 alkylthio, linear or branched Cι-C2o(Cι-Cι θ alkoxy)alkyl, linear or branched Cι-C 2 o(Cι-C5 alkylthio)alkyl, phenyl, aryl, heteroaryl, halogen, hydroxyl, formyl, acetyl, linear or branched C 1 -C 2 0 alkanoyl, linear or branched C3-C20 alkenoyl, linear or branched Cs-C 2 o polyalkenoyl, benzoyl, aroyl, heteroaroyl, nitrile, carboxyl, formyl, Cι-C 20 alkoxycarbonyl, C1-C20 N-alkylamido, C1-C20 NN-dialkylamido, amido, nitro, amino, C1-C20 alkylamino, C1-C20 dialkylamino, C2-C20 dialkenylamino, C4-C20 di(polyalkenyl)amino, arylamino, diarylamino, C1-C20 alkylarylamino, and cyclic-amino groups (for example but not exclusively aziridino, pyrrolidino, piperidino, morpholino, thiomorpholino, indolino, piperazino, linear or branched C1-C20 N-alkylpiperazino, linear or branched C1-C20 N- hydroxyalkylpiperazino, N-phenylpiperazino, N-arylpiperazino, homopiperidino, N- indolinyl), arylsulfanyl, aryloxy, arylsulfinyl, arylsulfonyl, linear or branched C1-C20 alkylsulfonyl, di-(Cι-Cιo alkoxyalkyl)phosphonyl in addition to those substituents specified for R l through to and including R 1 . X may be selected from O, S, ΝH, ΝR 6 . Furthermore the function R 8 X may be taken as a whole and selected from the following cyclic nitrogen containing moieties aziridino, mono- or poly- substituted linear or branched C 1 -C 2 0 alkyl aziridino, pyrrolidino, mono- or poly- substituted linear or branched C 1 -C 2 0 alkyl pyrrolidino, piperidino, mono- or poly- substituted linear or branched C 1 -C 20 al yl piperidino, morpholino, mono- or poly- substituted linear or branched C 1 -C 2 0 alkyl morpholino, thiomorpholino, mono- or poly- substituted linear or branched C1-C20 alkyl thiomorpholino, indolino, mono- or poly- substituted linear or branched C1-C20 alkyl indolino, piperazino, mono- or poly- substituted linear or branched Ci-C2o alkyl piperazino, linear or branched C 1 -C20 N-alkylpiperazino, linear or branched C1-C2Q N- hydroxyalkylpiperazino, N-phenylpiperazino, N-arylpiperazino, homopiperidino, mono- or poly- substituted linear or branched C 1 -C20 alkyl homopiperidino, N- indolinyL N-l,2,3,4-tetrahydroquinolinyl, N-l,2,3,4,4a,9a-hexahydrocarbazolyl). As mentioned above, certain values for R 7 and/or R 9 show diminished intensity of the generated colour at ambient temperatures. These values are generally electron releasing groups. Preferably the electron releasing groups for R 7 and/or R 9 are each selected from linear or branched - -o alkoxy, linear or branched C,-C 20 alkylthio, linear or branched C 1 -C 20 (C 1 -C 10 alkoxy)alkyl, linear or branched Cι-C 20 (C 1 -C 5 alkylthio)alkyl, hydroxyl, C C 20 N-alkylamido, C,-C 20 NN-dialkylamido, amido, amino, C r C 20 alkylamino, C,-C 20 dialkylamino, C 2 -C 20 dialkenylamino, C 4 -C 20 di(polyalkenyl)amino, arylamino, diarylamino, C r C 20 alkylarylamino, and cyclic-amino groups (for example but not exclusively aziridino, pyrrolidino, piperidino, homopiperidino, morpholino, thiomorpholino, indolino, piperazino, linear or branched C,-Cι 0 N-alkylpiperazino, linear or branched C r C 20 N-hydroxyalkylpiperazino, N-phenylpiperazino, N-arylpiperazino, homopiperidino), arylsulfanyl and aryloxy. Examples 7, 10, 12 and 13 illustrate 2,2-diaryl- 2H-naphtho[l,2-b]pyrans having the diminished intensity of generated colour at ambient temperatures feature. General Overview of Synthetic Strategies The 1-naphthols and related hydroxy compounds are either commercially available or obtained by known synthetic methods, or derived by such methods by persons skilled in the art of organic synthesis. In particular, the application of the Stobbe condensation to prepare numerous substituted 1-naphthols has been discussed (see Organic Reactions, Wiley, New York, 1951, volume 6, p. 1). Other routes to substituted 1-naphthols include the application of Bradsher cycloaddition methodology e.g. R. F. Frank et al., J. Chem. Soc, Chem. Commun., 1984, 761. The synthesis of the propargyl alcohols has been described in the scientific literature, see for example T.F. Rutledge in 'Acetylenic Compounds,' Reinhold, New York, 1968. The combination of the substituted 1-naphthols and the propargyl alcohols to afford the naphthopyran is well established (Scheme), see for example L. Merlini in 'Advances in Heterocyclic Chemistry,' Academic Press, 1975, vol. 18, p. 159; R. Guglielmetti in 'Photochromism: Molecules and Systems,' Studies in Organic Chemistry 40, eds. H. Durr and H. Bouas-Laurent, Elsevier, 1990. chp. 8; J. D. Hepworth, C. D. Gabbutt, B. M. Heron in 'Comprehensive Heterocyclic Chemistry π,' eds. A. R. Katritzky, C. W. Rees, E. E. V. Scriven, Pergamon, 1996, vol. 5, p. 351. Scheme The acid catalyst may be selected from acidic alumina (e.g. Brockmann 1), acetic acfcl, trifluoroacetic acid, silica, clays (e.g. montmorillonite, tonsil), acidic exchange resins, alkylbenzene sulfonic acids (e.g. toluenesulfonic acid). Organic solvents frequently employed for the reaction include benzene, toluene, xylene, and relatively high boiling alkanes. In order that the invention may be more fully understood, the following Examples are provided by way of illustration only. Examples 1. Methyl 8-methoxy-2-phenyl-2-(4-piperidinophenyl)-2H-naphtho[l,2-b]pyran- 5-carboxylate A solution of methyl 4-hydroxy-7-methoxy-2-naphthoate (5 mmol) and 1 -phenyl- 1 - (4-piperidinophenyl)prop-2-yn-l-ol (5 mmol) in toluene (60 cm 3 ) containing acidic alumina (Brockmann 1) (5g) was refluxed for 45 minutes. The cooled solution was filtered and the alumina residue washed well with ethyl acetate (5 x 40 cm 3 ). Removal of the dried solvent gave a brown gum which gradually crystallised on standing. Recrystallisation from ethyl acetate and hexane gave the title crystalline compound (m.p. = 169 - 171 °C). 2. Methyl 8-methoxy-2-(4-methoxyphenyl)-2-(4-morpholinophenyl)-2H- naphtho[ 1 ,2-b]pyran-5-carboxy late This compound was obtained by a similar protocol to example 1 above using the requisite starting materials (m.p. = 171 - 173 °C). 3. Methyl 7,8-dimethoxy-2-pheny l-2-(4-piperidinophenyl)-2H-naphtho[ 1 ,2- b]pyran-5-carboxylate This compound was obtained by a similar protocol to example 1 above using the requisite starting materials (m.p. = 151 -153 °C). 4. Methyl 8-methoxy-2,2-di(4-methoxyphenyl)-2H-naphtho[ 1 ,2-b]pyran-5- carboxylate This compound was obtained by a similar protocol to example 1 above using the requisite starting materials (m.p. = 173 - 175 °C). 5. Methyl 7,8-dimethoxy-2,2-di(4-methoxyphenyl)-2H-naphtho[l,2-/3]pyran-5- arboxylate This compound was obtained by a similar protocol to example 1 above using the requisite starting materials (m.p. = 157 -159 °C). 6. Methyl 8, 10-dimethoxy-2,2-di(4-methoxyphenyl)-2H-naphtho[l,2-b]pyran-5- carboxylate This compound was obtained by a similar protocol to example 1 above using the requisite starting materials (m.p. = 196 - 198 °C). 7. Methyl 9-methoxy-2,2-di(4-methoxyphenyl)-2H-naphtho[l,2-b]pyran-5- carboxylate This Example is provided for the purposes of comparison only. This compound was obtained by a similar protocol to example 1 above using the requisite starting materials (m.p. = 162 - 164 °C). 8. Methyl 2-(4-methoxyphenyl)-2-(4-morpholinophenyl)-2H-naphtho[l,2- b]pyran-5-carboxylate This Example is provided for the purposes of comparison only. This compound was obtained by a similar protocol to example 1 above using the requisite starting rnaterials (m.p. = 177 - 179 °C). 9. Methyl 2-phenyl-2-(4-piperidinophenyl)-2H-naphtho[l,2-b]pyran-5- carboxylate . This Example is provided for the purposes of comparison only. This compound was obtained by a similar protocol to example 1 above using the requisite starting materials (m.p. = 1 17 - 120 °C). 10. Methyl 7-methoxy-2-phenyl-2-(4-piperidinophenyl)-2H-naphtho[T,2- b]pyran-5-carboxylate χ i s Example is provided for the purposes of comparison only. This compound was obtained by a similar protocol to example 1 above using the requisite starting materials (m.p. = 179 -182 °C). 11. -Methyl 2,2-di(4-methoxyphenyl)-2H-naphtho[ 1 ,2-b]pyran-5-carboxylate. This Example is provided for the purposes of comparison only. This compound was obtained by a similar protocol to example 1 above using the requisite starting materials (m.p. = 133 - 135 °C). 12. Methyl 7-methoxy-2,2-di(4-methoxyphenyl)-2H-naphtho[l,2-b]pyran-5- carboxylate . This Example is provided for the purposes of comparison only. This compound was obtained by a similar protocol to example 1 above using the requisite starting materials (m.p. = 151 - 153 °C). 13. Methyl 8,9-dimethoxy-2-phenyl-2-(4-piperidinophenyl)-2H-naphtho[ 1 ,2- b]pyran-5-carboxylate. This Example is provided for the purposes of comparison only. This compound was obtained by a similar protocol to example 1 above using the requisite starting materials (m.p. = 145.5 - 147.5 °C). Example 14 Table of data presented to illustrate the claimed effect: All data recorded for solutions of comparable concentrations in toluene at 20 C, under standard irradiation conditions; n at 20°C = half-life in seconds of sample in toluene maintained at 20 °C. Absorbance to is the maximum steady state absorbance reading of a solution after constant irradiation. Absorbance tio is the 'absorbance of the foregoing solution 10 seconds after irradiation is terminated. Absorbance / mole is calculated using data from Absorbance to and the concentration of each solution. * Denotes example included in the table for comparative purpose.

Claims: CLAIMS: A 2H-naphtho[ l,2-b]pyran of the general formula (I) wherein R 1 and/or R 2 , which may be the same of different, are each selected from phenyl, mono-, di- or poly- substituted aryl groups, unsubstituted, mono-, di- or poly- substituted naphthyl groups and unsubstituted mono-, di- or poly- substituted heteroaryl groups, wherein when substituted, the substitutents are each selected from linear or branched - Q alkyl, C 3 -C 20 cycloalkyl, C 4 -C 20 bicycloalkyl, C 5 -C 20 polycycloalkyl, linear or branched -C^ haloalkyl, linear or branched C^C^ perhaloalkyl, linear or branched C 2 -C 20 alkenyl, linear or branched C 4 -C 20 polyalkenyl, linear or branched C 2 -C 20 alkynyl, linear or branched C 4 -C 20 polyalkynyl, linear or branched C^C^ hydroxyalkyl, linear or branched C ι -C 20 polyhydroxyalkyl, linear or branched C r C 20 alkoxy, linear or branched -C^ alkyl.thio, linear or branched C 1 -C 20 (C 1 -C 5 or C, - C 10 alkoxy)alkyl, linear or branched C 1 -C 20 (C 1 -C 5 alkylthio)alkyl, phenyl, aryl, heteroaryl, halogen, hydroxyl, formyl, acetyl, linear or branched C 3 -C 20 alkenoyl, linear or branched C 5 -C 20 polyalkenoyl, nitrile, carboxyl, - o alkoxycarbonyl, C,-C 10 N-alkylamido, C,- C 20 NN-dialkylamido, amido, nitro, amino, C r C 20 alkylamino, C 2 -C 20 dialkylamino, C 2 -C 20 dialkenylamino, C 4 -C 20 di(polyalkenyl)amino, arylamino, diarylamino, Cι-C 20 alkylarylamino, cyclic-amino groups, arylsulfanyl, aryloxy, arylsulfmyl, arylsulfonyl, linear or branched C,-C 20 alkylsulfonyl and di-C -Cn, or - o alkoxyalkyl)phosphonyl or from the fused saturated heterocycles II, III and IV in which n and m are integers between 2 and 5 and may be the same or different, II IV wherein R 13 is selected from linear or branched C r C 20 alkyl, C 3 -C 20 cycloalkyl, C 4 - C 20 bicycloalkyl, C 5 -C 20 polycycloalkyl, linear or branched -C 20 hydroxyalkyl, linear or branched C x -C 10 haloalkyl, linear or branched - o perhaloalkyl, phenyl, C,-C 20 linear or branched alkylsulfonyl, aryl, tosyl, arylsulfonyl, acyl, linear or branched - o alkylcarbonyl, benzoyl, aroyl, substituted aroyl and butoxycarbonyl; R 3 and R\ which may be the same or different, are each selected from hydrogen, linear or branched C^C^ alkyl, C 3 -C 20 cycloalkyl, C 4 -C 20 bicycloalkyl, C 5 -C 20 polycycloalkyl, linear or branched C 1 -C 20 haloalkyl, linear or branched C r C 20 perhaloalkyl, linear or branched C 2 -C 20 alkenyl, linear or branched C 4 - C 20 polyalkenyl, linear or branched C 2 -C 20 alkynyl, linear or branched C 4 -C 20 polyalkynyl, linear or branched C 1 -C 20 hydroxyalkyl, linear or branched C r C 20 polyhydroxyalkyl, linear or branched C r C 20 alkoxy, linear or branched C C 2 o alkylthio, linear or branched C 1 -C 20 (C 1 -C J alkoxy)alkyl, linear or branched C,- C 2 o(C r C 5 or C r C 10 alkylthio)alkyl, phenyl, aryl, heteroaryl, halogen, hydroxyl, formyl, acetyl, linear or branched C 3 -C 20 alkenoyl, linear or branched C 5 -C 20 polyalkenoyl, nitrile, carboxyl, C C 5 alkoxycarbonyl, C r C 5 N-alkylamido C,-C 5 N,N-dialkylamido, amido and nitro, in addition to those groups specified for R 1 and/or R 2 ; R 5 is selected from the substituents specified for R 1 and/or R 2 or linear or branched C,-C 20 alkylcarbonyl, benzoyl, aroyl, heteroaroyl. R 7 and R 10 which may be the same of different, are each selected from hydrogen, linear or branched C,-C 20 alkyl, C 3 -C 20 cycloalkyl, C 4 -C 20 bicycloalkyl, C 5 -C 20 polycycloalkyl, linear or branched - Q haloalkyl, linear or branched C[-C 20 perhaloalkyl, linear or branched C 2 -C 20 alkenyl, linear or branched C 4 -C 20 polyalkenyl, linear or branched C 2 -C 20 alkynyl, linear or branched C 4 -C 20 polyalkynyl, linear or branched Cι-C 20 hydroxyalkyl, linear or branched C,-C 20 polyhydroxyalkyl, linear or branched C r C 20 alkoxy, linear or branched - o alkylthio, linear or branched C 1 -C 20 (C 1 -C 5 alkoxy)alkyl, linear or branched C C 20 (C 1 -C 10 alkylthio)alkyl, phenyl, aryl, heteroaryl, halogen, hydroxyl, C r C 20 N-alkylamido, - o NN-dialkylamido, amino, -C 20 alkylamino, -C 20 dialkylamino, C 2 -C 20 dialkenylamino, C 4 -C 20 di(polyalkenyl)amino, arylamino, diarylamino, - Q alkylarylamino, cyclic-amino groups, arylsulfanyl and aryloxy; R 6 , R 8 , R 9 , R 11 , R 12 , R 14 , and R 15 , which may be the same or different, are each selected from the substituents of R 1 , R 2 , R 5 , and hydrogen; R 16 , of which there may be one or more, the same or different, is selected from any of those substituents specified for R 1 to R 15 inclusive; X is selected from O, S, ΝH, ΝR 6 or the function R 8 X is selected from aziridino, mono- or poly- substituted linear or branched -C 20 alkyl aziridino, pyrrolidino, mono- or poly- substitued linear or branched -C JO alkyl pyrrolidino, piperidino, mono- or poly- substituted linear or branched C,-C 20 alkyl piperidino, morpholino, mono- or poly- substituted linear or branched C,-C 20 alkyl morpholino, thiomorpholino, mono- or poly- substituted linear or branched C x -C 20 alkyl thiomorpholino, indolino, mono- or poly- substituted linear or branched C,- C 20 alkyl indolino, piperazino, mono- or poly- substituted linear or branched C,-C 20 alkyl piperazino, linear or branched C,-C 20 N-alkylpiperazino, linear or branched C r C 20 N-hydroxyalkylpiperazino, N-phenylpiperazino, N-arylpiperazino, homopiperidino, mono- or poly- substituted linear or branched C,-C 20 alkyl homopiperidino, N-indolinyl, N-l,2,3,4-tetrahydroquinolinyl and N- 1,2,3, 4,4a, 9a- hexahydrocarbazolyl. 2. A 2H-naphtho[l,2-b]pyran according to claim 1, wherein R 7 and/or R 9 are each selected from linear or branched C,-C 20 alkoxy, linear or branched C,- C 20 alkylthio, linear or branched C 1 -C 20 (C 1 -C 10 alkoxy)alkyl, linear or branched C,- C 20 (C 1 -C 5 alkylthio)alkyl, hydroxyl, C,-C 20 N-alkylamido, C r C 20 NN- dialkylamido, amido, amino, C r C 20 alkylamino, C r C 20 dialkylamino, C 2 -C 20 dialkenylamino, C 4 -C 20 di(polyalkenyl)amino, arylamino, diarylamino, C r C 20 alkylarylamino, cyclic-amino groups, arylsulfanyl and aryloxy. 3. A 2H-naphtho[l,2-b]pyran according to claim 1 or 2, wherein the substituted heteroaryl groups are selected from thienyl, benzothienyl, furyl, berizofuryl, pyrryl, indolyl, pyridyl, quinolyl, isoquinolyl, pyrimidyl, oxazolyl, isoxazolyl, thiazolyl, isothiazolyl, pyrazolyl, imidazolyl, benzimidazolyl, triazolyl, benzotriazolyl and tetrazolyl. 4. A 2H-naphtho[l,2-b]pyran according to claim 1, 2 or 3, wherein the cyclic-amino group is selected from aziridino, pyrrolidino, piperidino, morpholino, thiomorpholino, indolino, piperazino, linear or branched C,-C 10 N-alkylpiperazino, linear or branched -C^ N-hydroxyalkylpiperazino, N-phenylpiperazino, N- arylpiperazino, N-indolinyl and homopiperidino. 5. A 2H-naphtho[l,2-b]pyran according to claim 1, 2, 3 or 4, wherein the C 4 -C 20 bicycloalkyl group is norbornyl and the C 5 -C 20 polycycloalkyl group is adamantyl. 6. A 2H-naphtho[ l,2-b]pyran according to the general formula (I) of claim 1, wherein R 1 and R 2 are 4-methoxyphenyl, R 5 is methoxycarbonyl, R 8 is methyl, X is O and R 3 , R 4 , R 6 , R 7 , R 9 and R 10 are each hydrogen. 7. A 2H-naphtho[ l,2-b]pyran according to the general formula (I) of claim 1, where R 1 is 4-morpholinophenyl, R 2 is 4-methoxyphenyl, R 5 is methoxycarbonyl, R 8 is methyl, X is O and R 3 , R 4 , R 6 , R 7 , R 9 and R 10 are each hydrogen. 8. A 2H-naphtho[l,2-b]pyran according to the general formula (I) of claim 1, where R 1 is 4-morpholinophenyl, R 2 is 4-methoxyphenyl, R 5 is methoxycarbonyl, R 8 X is pyrrolidino and R 3 , R 4 , R 6 , R 7 , R 9 and R 10 are each hydrogen. 9. A 2H-naphtho[ l,2-b]pyran according to the general formula (I) of claim 1, where R 1 and R 2 are 4-methoxyphenyl, R 5 is methoxycarbonyl, R 8 X is pyrrolidino and R 3 , R 4 , R 6 , R 7 , R 9 and R 10 are each hydrogen. 10. A 2H-naphtho[l,2-b]pyran according to the general formula (I) of claim 1, where R 1 is 4-morpholinophenyl, R 2 is phenyl, R 5 is methoxycarbonyl, R 8 is methyl, X is O and R 3 , R 4 , R 6 , R 7 , R 9 and R 10 are each hydrogen. 11. A 2H-naphtho[l,2-b]pyran according to the general formula (I) of claim 1, where R 1 is 4-piperidinophenyl, R 2 is 4-methoxyphenyl, R 5 is methoxycarbonyl, R 8 is methyl, X is O and R 3 , R 4 , R 6 , R 7 , R 9 and R 10 are each hydrogen. 12. A 2H-naphtho[l,2-b]pyran according to the general formula (I) of claim 1, where R 1 is 4-piperidinophenyl, R 2 is phenyl, R 5 is methoxycarbonyl, R 8 is methyl, X is O and R 3 , R 4 , R 6 , R 7 , R 9 and R 10 are each hydrogen. 13. A 2H-naphtho[ l,2-b]pyran according to the general formula (I) of claim 1, where R 1 is 4-piperidinophenyl, R 2 is phenyl, R 5 is methyl, R 8 is methyl, X is O and R 3 , R\ R 6 , R 7 , R 9 and R 10 are each hydrogen. 14. A 2H-naphtho[ l,2-b]pyran according to the general formula (I) of claim 1, where R 1 and R 2 are 4-methoxyphenyl, R 5 and R 6 are methyl, R 8 is methyl, X is O and R 3 , R 4 , R 7 , R 9 and R 10 are each hydrogen. 15. A 2H-naphtho[ l,2-b]pyran according to the general formula (I) of claim 1, where R 1 is 4-morpholinophenyl, R 2 is phenyl, R 5 is methoxycarbonyl, R 8 is methyl, R 9 is methoxy, X is O and R 3 , R 4 , R 6 , R 7 and R 10 are each hydrogen. 16. A 2H-naphtho[l,2-b]pyran according to the general formula (I) of claim 1, where R 1 is 4-morpholinophenyl, R 2 is phenyl, R 5 is methoxycarbonyl, R 8 is methyl, R 10 is methoxy, X is O and R 3 ,R 4 , R 6 , R 7 and R 9 are each hydrogen. 17. A 2H-naphtho[l,2-b]pyran according to the general formula (I) of claim 1, where R 1 is 4-morpholinophenyl, R 2 is phenyl, R 5 is methoxycarbonyl, R 8 is methyl, R 9 is dimemylamino, X is O and R 3 , R 4 , R 6 , R 7 and R 10 are each hydrogen. 18. A 2H-naphtho[l,2-b]pyran according to the general formula (I) of claim 1, where R 1 is 4-morpholinophenyl, R 2 is 4-methoxyphenyl, R 5 is methoxycarbonyl, R 8 is methyl, R 9 is methoxy, X is O and R 3 , R 4 , R 6 , R 7 and R 10 are each hydrogen. 19. A 2H-naphtho[l,2-b]pyran according to the general formula (I) of claim 1, where R l is 4-morpholinophenyl, R 2 is 4-methoxyphenyl, R 5 is methoxycarbonyl, R 8 is methyl, R 10 is methoxy, X is O and R 3 ,R 4 , R 6 , R 7 and R 9 are each hydrogen. 20. A 2H-naphtho[ l,2-b]pyran according to the general formula (I) of claim 1, where R 1 is 4-morpholinophenyl, R 2 is 4-methoxyphenyl, R 5 is methoxycarbonyl, R 8 is methyl, R 9 is dimethylamino, X is O and R 3 , R 4 , R 6 , R 7 and R !0 are each hydrogen. 21. A 2H-naphtho[ l,2-b]pyran according to the general formula (I) of claim 1, where R 1 is 4-piperidinophenyl, R 2 is phenyl, R 5 is methoxycarbonyl, R 8 is methyl, R 9 is methoxy, X is O and R\ R 4 , R 6 , R 7 and R 10 are each hydrogen. 22. A 2H-naphtho[l,2-b]pyran according to the general formula (I) of claim 1, where R 1 is 4-piperidinophenyl, R 2 is phenyl, R 5 is methoxycarbonyl, R 8 is methyl, R 10 is methoxy, X is O and R 3 ,R 4 , R 6 , R 7 and R 9 are each hydrogen. 23. A 2H-naphtho[ l,2-b]pyran according to the general formula (I) of claim 1, where R 1 is 4-piperidinophenyl, R 2 is phenyl, R 5 is methoxycarbonyl, R 8 is methyl, R 9 is dimethylamino, X is O and R 3 , R 4 , R 6 , R 7 and R 10 are each hydrogen. 24. A 2H-naphtho[l,2-b]pyran according to the general formula (I) of claim 1, where R 1 is 4-piperidinophenyl, R 2 is 4-methoxyphenyl, R 5 is methoxycarbonyl, R 8 is methyl, R 9 is methoxy, X is O and R 3 , R 4 , R 6 , R 7 and R 10 are each hydrogen. 25. A 2H-naphtho[l,2-b]pyran according to the general formula (I) of claim 1, where R 1 is 4-piperidinophenyl, R 2 is 4-methoxyphenyl, R 5 is methoxycarbonyl, R 8 is methyl, R 10 is methoxy, X is O and R ,R 4 , R 6 , R 7 and R 9 are each hydrogen. 26. A 2H-naphtho[ l,2-b]pyran according to the general formula (I) of claim 1, where R 1 is 4-piperidinophenyl, R 2 is 4- methoxyphenyl, R 5 is methoxycarbonyl, R 8 is methyl, R 7 is dimethylamino, X is O and R\ R 4 , R 6 and R 10 are each hydrogen. 27. A 2H-naphtho[ l,2-b]pyran according to the general formula (I) of claim 1, where R 1 is 2,4-dimethoxyphenyl, R 2 is 4-methoxyphenyl, R 5 is methoxycarbonyl, R 8 is methyl, X is O and R 3 , R 4 , R 6 , R 7 , R 9 and R 10 are each hydrogen. 28. A 2H-naphtho[l,2-b]pyran according to the general formula (I) of claim 1, where R 1 is 4-piperidinophenyl, R 2 is phenyl, R 5 is methoxycarbonyl, R 8 is methyl, R 7 is methoxy, X is O and R 3 , R 4 , R 6 and R 10 are each hydrogen. 29. A 2H-naphtho[l,2-b]pyran according to the general formula (I) of claim 1, where R 1 is 4-piperidinophenyl, R 2 is phenyl, R 5 is methoxycarbonyl, R 8 is methyl, X is S and R 3 , R 4 , R 6 , R 7 , R 9 and R 10 are each hydrogen. 30. A 2H-naphtho[l,2-b]pyran according to the general formula (I) of claim 1, where R 1 is 4-piperidinophenyl, R 2 is phenyl, R 5 is methoxycarbonyl, R 8 is methyl, X is NR 6 , where R 6 is methyl and R 3 , R 4 , R 7 , R 9 and R 10 are each hydrogen. 31. A 2H-naphtho[l,2-b]pyran according to the general formula (I) of claim 1, where R 1 and R 2 are 4-methoxyphenyl, R 5 is methoxycarbonyl, R 8 is methyl, R 7 is methoxy, X is O and R 3 , R 4 , R δ and R 10 are each hydrogen. 32. A 2H-naphtho[l,2-b]pyran according to the general formula (I) of claim 1, where R 1 and R 2 are 4-methoxyphenyl, R 5 is methoxycarbonyl, R 8 is methyl, X is O, R 10 is methoxy and R 3 , R 4 , R 6 , R 7 and R 9 are each hydrogen. 33. A 2H-naphtho[l,2-b]pyran according to the general formula (I) of claim 1, where R 1 and R 2 are 4-methoxyphenyl, R 5 is methoxycarbonyl, R 8 is methyl, X is O, R 7 is methoxy and R 3 , R 4 , R δ and R 10 are each hydrogen. 34. An ink including a pyran according to any preceding claim. 35. A fuel including a pyran according to any of claims 1 to 33. 36. A polymeric host material including a pyran according to any of claims 1 to 33. 37. A polymeric host material according to claim 36, wherein the material is a plastic or glass. 38. A window, an ophthalmic lens, a sunglass lens, a protective visor, a screen, a film, a container, a mirror or a vehicle body panel including a polymeric host material according to claim 36 or 37.

Inventors: CLARKE DAVID ALLAN, CORNS STEPHEN NIGEL, GABBUTT CHRISTOPHER DAVID, HEPWORTH JOHN DAVID, HERON BERNARD MARK, PARTINGTON STEVEN MICHAEL, CLARKE, DAVID, ALLAN, CORNS, STEPHEN, NIGEL, GABBUTT, CHRISTOPHER, DAVID, HEPWORTH, JOHN, DAVID, HERON, BERNARD, MARK, PARTINGTON, STEVEN, MICHAEL
Applicants: CLARKE DAVID ALLAN, CORNS STEPHEN NIGEL, GABBUTT CHRISTOPHER DAVID, HEPWORTH JOHN DAVID, HERON BERNARD MARK, JAMES ROBINSON LTD, PARTINGTON STEVEN MICHAEL, CLARKE, DAVID, ALLAN, CORNS, STEPHEN, NIGEL, GABBUTT, CHRISTOPHER, DAVID, HEPWORTH, JOHN, DAVID, HERON, BERNARD, MARK, JAMES ROBINSON LIMITED, PARTINGTON, STEVEN, MICHAEL
Application year: 1999
Main classification: C07D311
IPC codes: C07D311, G02B5