Christopher D. Gabbutt

Synthesis and Photochromic Properties of Methoxy Substituted 2,2-Diaryl-2H-naphtho[1,2-b]pyrans

A series of methoxy-substituted 2,2-di(4-methoxyphenyl)-2H-naphtho[1,2-b]pyrans has been synthesised from 3-alkoxycarbonyl-1-naphthols and 1,1-di(4-methoxyphenyl)prop-2-yn-1-ol. The influence of the methoxy group on the wavelength of maximum absorption and the stability of the ring-opened naphthopyrans is discussed.

Control of the Fading Properties of Photochromic 3,3-Diaryl-3H-naphtho[2,1-b]pyrans

The synthesis and spectroscopic properties of some novel photochromic 3H-naphtho[2,1-b]pyrans are reported. Varying the size of an ortho-substituent on one of the geminal aryl rings allows the rate of fade of the photogenerated color to be controlled.

Extending human perception of electromagnetic radiation to the UV region through biologically inspired photochromic fuzzy logic (BIPFUL) systems

Photochromic fuzzy logic systems have been designed that extend human visual perception into the UV region. The systems are founded on a detailed knowledge of the activation wavelengths and quantum yields of a series of thermally reversible photochromic compounds. By appropriate matching of the photochromic behaviour unique colour signatures are generated in response differing UV activation frequencies.

Unusual aminations with tetramethylguanidine

Heating activated halobenzenes with 1,1,3,3-tetramethylguanidine affords mixtures of dimethylaminobenzenes and 2-aryl-1,1,3,3-tetramethylguanidines.

Directed lithiation of some chroman-4-ols

Directed lithiation of chroman-4-ols occurs predominantly at C-5 under kinetic control, but at C-8 at higher temperatures. Dehydration and oxidation of the products provides viable routes to 5-substituted 2H-chromenes and chroman-4-ones, respectively. The chroman-4-ones have been converted into novel pyrano[4,3,2-de] phthalazines. 2,2,5,7-Tetramethylchroman-4-ol is preferentially lithiated at the 5-methyl group and leads to the pyrano[2,3,4-de][1]benzopyran system.

An unusual ring expansion from the Zav’yalov pyrrole synthesis: formation of oxacino[2,3-c]pyrroles

Enamino acids 2 and 5 undergo a facile cyclisation to afford the pyrrole 3 and isoindole 6 ring systems; a novel two atom ring expansion ensues when derivatives 5b,d are subjected to the cyclisation conditions, resulting in the formation of the new oxacino[2,3-c]pyrrole system, the structure of which is confirmed by X-ray crystallography.

Hexatriene formation from the regiospecific alkene cross-metathesis of trans-1-(buta-1,3-dien-1-yl)-2-acryloyloxynaphthalene

Wittig olefination of 2-hydroxy-1-naphthaldehyde with allylidenetriphenylphosphorane afforded trans-1-(buta-1,3-dien-1-yl)-2-naphthol in good yield. Subsequent O-acylation with acryloyl chloride provided the corresponding acrylate ester. Attempts to effect cyclisation of the latter by ring-closing metathesis with Grubbs’ 2nd generation catalyst failed to provide 5H-naphth[2,1-b]oxocin-5-one and instead induced a novel cross-metathesis reaction to generate trans,trans,trans-1,6-bis(2-acryloyloxynaphthalen-1-yl)hexa-1,3,5-triene, the structure of which was established by 1H NMR spectroscopy and by X-ray crystallography.

A novel acylative ring cleavage of benzothieno[3,2-b]pyran-4-ols: application to the synthesis of dibenzothiophenes and fused-ring derivatives

The benzothienopyranols 3, readily available from the ketone 1, are transformed to the carbamates 5 on treatment with N,N-dimethylcarbamoyl chloride, subsequent thermal electrocyclisation provides access to dibenzothiophene derivatives 6 and 11–13.

A Facile Synthesis of SomeBenzothiopyrano[4,3-b]pyrroles†

A simple synthesis of some benzothiopyrano[4,3-b]pyrroles from benzothiopyran-4-ones is described which has been used to prepare the novel heterocyclic system 4H-naphtho[1′,2′:5,6]thiopyrano[4,3-b ]pyrrole.