Pyrex filtered Hanovia lamp

The natural product (-)-oxetanocin is an unprecedented oxetanosyl-A/-glycoside that inhibits the in vitro replication of human immunodeficiency virus (HIV). In order to prepare multigram quantities of the compound, D.W. Norbeck et al. devised a short and efficient synthetic strategy. The cornerstone of the strategy was the Wolff rearrangement of a five-membered diazo ketone. The diazo transfer was achieved by first converting the ketone to an enamino ketone followed by treatment with triflyl azide. Upon irradiation with a 450 W Pyrex filtered Hanovia lamp, the isomeric oxetanes (a 3 = 2 1) were obtained in 36% yield. 

A solution of the 2-azido ester or amide (ca. 2 g) in a mixture of MeOII (95 mL) and sodium-dried THF (95 mL) was photolyzed under N2 in a Hanovia photochemical reactor (110-W medium-pressure Hg lamp with a Pyrex filter). The reaction was monitored by observing the rate of disappearance of the absorption band (Nf) at 2140 cm 1 (irradiation times of 3-5 h were generally required). When the reaction was complete the solvent was removed in vacuo and the brown residual oil chromatographed on alumina [petroleum ether (bp 60-803C)/benzene 7 3]. Further elution with benzene followed by removal of the solvent gave the product (the esters as pale yellow oils, the amides as crystalline solids), which were further purified by vacuum distillation or by recrysiallization. 

Acridine-9-carbonitrile 10-oxide (la 3.00g, 13.6 mmol) in benzene (1.8 L) in a quartz immersion well was irradiated for 3 h with a Hanovia high-pressure 450-W Hg lamp equipped with a Pyrex filter. The resulting solution was evaporated under reduced pressure and the residue was extracted with pentane (3 x 50 mL). The combined extracts were evaporated under reduced pressure at 20 C to give orange crystals yield 1.8 g (60%) mp 105-109 C (Et20/pentane). 

The photochemical and thermal transformations of 5-methyldihydro-thiazolo[3,2-a]pyridinium-8-olate (515) have been investigated. Irradiation using a Hanovia mercury lamp and Pyrex filter gives the isomeric pyridone 516 (4%). When a Rayonet reactor was used, a product which appears to be the valence tautomer 517 (6%) was isolated. Further irradiation of 517 gave... 

Solid-state photolysis was performed using a 450-W hanovia medium-pressure mercury lamp fitted with a Pyrex filter (X >290 nm). The crystalline la was irradiated for 22.5 h at -20 °C to give a mixture of exo-isomer 3a and endo-isomer 4a in 63 and 12% yield, respectively. 

An emulsion of 1 (1 g, 2.77 mmol) in distilled water (150 mL) was irradiated using a 450-W medium-pressure Hanovia lamp and a Pyrex filter for 36 h with stirring. The photolyzed mixture was extracted with dichloromethane. Removal of tlie solvent in vacuo gave a thick residue. It was then stirred with methanol for about 6 h. Solvent was removed in vacuo to give a residue that was chromatographed over a silica gel column. Elution with a mixture of 15% ethyl acetate in PE gave 3 as a white solid, mp 41 °C (230 mg, 21%), which was crystallized with difficulty from a mixture of n-pentane and dichloromethane (4 1). 

A suspension of the compound (0.5-1 g) in distilled water (150 mL) was irradiated with stilling using a Hanovia medium-pressure 450-W lamp and a Pyrex filter for ca. 35 h. The suspension was then extracted with CH2CI2 and the residue obtained after removal of solvent was chromatographed on a silica gel column (60-120 mesh). The ketene was eluted with a mixture of ethyl acetate (5-10%) in petroleum ether (bp 60-80 °C). 

Anthraquinone photosensitised irradiation of tertiary N-allylamines in the presence of aP-unsaturated esters gives good yields of lactams. Using pyrex-filtered output (X>290 nm) from a 450 W medium pressure Hanovia lamp, for example, A-allylpiperidine and methyl methacrylate reacted in acetonitrile to give a 2 3 diastereomeric mixture (2S, 9S 2R, 95) of the indolizidone 1. 

UV irradiation of 65 in benzene (about 4 mM) with a medium-pressure Hg Hanovia lamp using Pyrex glassware as a filter (k > 290 nm) revealed products that are consistent with the expected x-cleavage and decarbony-lation followed by radical-radical reactions (07OL4351). 2,3-... 

However, 2,5-diphenyltellurophene, when irradiated in diethyl ether solution with a 450-watt Hanovia medium pressure mercury arc lamp equipped with a Pyrex filter, was recovered quantitatively1. 

The checkers used a Vycor immersion well and a Pyrex filter sleeve. The immersion well, 450-W mercury lamp, and the requisite transformer are available from Hanovia Lamp Division, Canrad-Hanovia Inc, 100 Chestnut Street, Newark, NJ 07105. 

Lamps and filters. The combination of radiation source and filter accounts for the actual radiation wavelength to which the reaction mixture is exposed. An unavoidable filter is the glass type of the reaction vessel. In the direct irradiation of substrates not containing functionality other than the phenyl groups, wavelengths in the 280 nm region are needed. Typically a Hanovia 450 W medium-pressure mercury lamp and a 2 mm Corex cylindrical filter (X > 270 nm) are employed. Triplet-sensitized reactions need a higher cut-off, which can be obtained by the use of the same lamp with a 2 mm Pyrex filter (X > 300 nm). The Rayonet photoreactor can be equipped with 254, 300 and 350 nm lamps. 

A mixture of adenine (2 g, 14.8 mmol), DTBP (8 mL), i-PrOH (135 mL), and H O (40 mL) was irradiated (Hanovia 450-W high-pressure Hg vapor lamp, Pyrex filter) for 22 h. Excess reagents were removed under reduced pressure and the solid residue was chromatographed [silica gel (500 g), MeOH/CHClj 1 10] to give 8-(l-hydroxy-l-methylethyl)adenine yield 2.66 g (96%). 

Methoxyphenacyl esters were first described by Sheehan and Umezawa in 1973.They studied the deprotection of a series of amino acids and found that the best yields were obtained when the photolysis was carried out in ethanol. The 4-methoxyphenacyl esters were formed by the reaction of the free acid with 4-methoxyphenacyl bromide in DMF containing triethylamine. Photolyses were carried out with a 450-W Hanovia mercury immersion lamp fitted with a Pyrex filter. The 4-methoxyphenacyl group was used in a synthesis of thymo-pentin analogues.The authors used zinc dust as the standard deprotection procedure for cleavage of phenacyl esters (see Section 2.2). 

A solution of thionocarbonate 86 (11.16 mg, 26.8 mmol) [Eq. (16)] in 54 mL of toluene was placed in a Hanovia photolysis apparatus and allyltributylstannane (17.68 mg, 53.6 mmol) was added. After thoroughly degasing the solution with argon, it was irradiated during 65 h at room temperature with a 450-W Hanovia lamp with Pyrex filter. Solvent was removed under reduced pressure, and the crude product was purified by chromatography over silica gel (ether-hexane, 5 95) affording 87 (6.25 g, 80%) as a colorless oil mp 43°-44°C [a]j, -70.3° (c 0.08, CHjCy. 

Different methods have been used to follow crosslinking reactions. When polymers were irradiated by U. V. light in dilute THF solution above 200 nm (Method A) or 300 nm (Method B), the insolubilization reaction was followed by measuring the solution ultra violet absorbance versus time. Likewise the course of disappearance of cinnamic structure was measured on polymers films placed on quartz at 9cm of the lamp and irradiated above 200 nm (Method C). Lamp used for methods A and C was a PCQ 9 G-1 which emits in the U.V. region at 253.7 (2.5 W), 312.5, 365 nm, the other rays being in visible. A Pyrex filter was placed beetween 450 W Hanovia lamp and solution when only higher wave lenghts were expected. Lamps powers were controled before and after irradiation with a Black-Ray Ultra-Violet Intensity Meter. 

A solution of l-(3,3-dimethyl-2-phenylcycloprop-l-enyl)-4-methylpentane (188 mg) and thioxanthone (19 mg) in benzene (200mL) was irradiated for 15 min with a 450-W Hanovia lamp with a Pyrex glass filter sleeve. The solvent was removed under reduced pressure and the residue was subjected to column chromatography (silica gel, hexane). The major fraction was the title compound yield 117 mg (63%). 

Z)-But-2-ene (6.3 g, 0.11 mmol) was condensed into a tube containing 4-tolyldiazomethane (95 mg, 0.72 mmol) and benzophenone (750 mg, 4.1 mmol). After sealing, the tube was irradiated with Pyrex-filtered light from a 450-W Hanovia medium-pressure Hg vapor lamp for 2 h. The solvent was removed under vacuum and the product was isolated by distillation. Total yield of products 92 mg (80%). Other examples b-d are also given. 

A solution of (Z,Z, )-l,2,6-triphenylhexa-l, 3,5-triene (10, 500 mg) in cyclohexane (500 mL) was irradiated under N2 for 2.5 h with a 450-W Hanovia lamp fitted with a Pyrex filter. The resulting solution was evaporated to a yellow oil which after crystallization from EtOH gave 380 mg (76%) mp 104-106"C. 

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