Naphthopyrane derivative

Kinetic Parameters for the Mesityl Site Exchange in Naphthopyrane Derivatives (83, 84, 85)... 

To this end, the naphthopyran derivative 44 was our first target, which could be derived from the a,p-unsaturated lactone 40 and the o-methylbenzoate 41 through Michael and Dieckmann reactions. It was expected that the pivotal conversion of a monomer 44 to a dimer 46 could be accomplished by oxidative coupling (Scheme 5). 

Photochromic [1,2-b] naphthopyran derivatives, (IV), prepared by Hughes [4] exhibited absorption in the 400-550 nm (brown) range and were used in graft copolymer reactions. 

Topics which have formed the subjects of reviews this year include photoinduced organic synthesis, photoisomerisations involving super-cyclophanes, regioselec-tive and stereoselective [2+2] photocycloadditions, position- and stereoselective photocyclisation, the photochemistry of indoles, five-membered heterocyclic compounds of the indigo group, pyrazoles and isothiazoles, and heterocyclic N-oxides, photochromic reactions of naphthopyran derivatives, photodegradation reactions of photochromic spirooxazines and 2H-chromenes, ° and chiral photo-chromic compounds. ... 

On the other hand, Yang etal. [33] have developed an organocatalyzed enantioselective FC-type addition reaction of 2-naphthol 212 with p,y-unsaturated a-ketoesters 209 using a cinchona alkaloid-derived thiourea catalyst 213 (Scheme 2.30). The resulting product 214 is in rapid equilibrium with the cyclic hemiketal 215, which was dehydrated with a catalytic amount of concentrated H SO in a one-pot fashion, providing the naphthopyran derivatives 216 with moderate to good yields (51-91%) and enantioselectivities (57-90% ee). 

An example of this sequential two-photon photochromism has been reported with a naphthopyran derivative [73]. This has the advantage, when it is used for optical data storage, of non-destructive readout capacity. 

Uchida M, Irie M (1993) Two-photon photochromism of a naphthopyran derivative. J Am Chem Soc 115 6442-6443... 

Phosphoric acid 25a was successfully employed for mediating enantioselective synthesis of 1,3-disubstituted isoindolines from electrophilic bifunctional substrates (containing an imine and a Michael acceptor site) and indoles [33]. Catalyst 7a was used effectively in an organocatalytic asymmetric F-C alkylation/cyclization cascade reaction between 1-naphthols and a,(i-unsaturated aldehydes to give chro-manes in good yields and select vities (Scheme 3 5.18) [ 10]. Furthermore, 2-naphthols and p,y-unsaturated a-keto ester also reacted in a F-C alkylation/dehydration sequence, in the presence of a thiourea catalyst and a catalytic amount of concentrated sulfuric acid, affording optically active naphthopyran derivatives [54]. 

The cyclisation of naphthyl propargyl ethers occurs efficiently under microwave irradiation leading to naphthopyrans, but naphthofurans are formed in the presence of base <96JCR(S)338>. The thermal rearrangement of naphthyl 3-trimethylsilylprop-2-ynyl ethers yields the 4-trimethylsilyl derivatives of naphthopyrans <96H(43)751>. 

All of the compounds discussed are based on three molecules 2/f-pyran (1), 4//-pyran (2) and the pyrylium cation (3). Names which have been used for the benzologue (4) of 2//-pyran include 2H- 1-benzopyran, benzo-a-pyran, chrom-3-ene and 2//-chromene. A similar situation exists for the corresponding derivative (5) of 4/f-pyran. The unambiguous and simplest name chromene is used in the present work. The benzologue (6) of pyrylium is known both as benzopyrylium and chromylium the former name is preferred here. Higher benzologues are referred to as naphthopyrans, such as 2H-naphtho[ 1,2-6 jpyran (7), but the names xanthene and xanthylium are used for (8) and (9). 

A number of oxynitroxide radicals that, although not ionic, are structurally similar to the nitroanions were obtained by adding in situ-generated triphenyl-germyl radicals to several nitro derivatives attention has been addressed to nitrospiro[indoline-naphthopyrans] 63, 66, and 67, and the resulting adducts have been attributed structures 70-72.59... 

The photochromic properties of naphthopyrans <05PHC33> and spiropyrans <05CHE281> have been reviewed. Electronic materials which incorporate six-membered O-and iS-heterocycles include derivatives of (2,6-dimethyl-47/-pyran-4-ylidene)propanedinitrile used as dopants for red organic LEDs <05JMAC2470>. Reviews of the organosulfur donor... 

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