Quinone diazides photolysis

The photolysis of o-quinone diazides was carefully investigated by Stis in 1944, many years before the development of photoresists. Scheme 10-102 shows the photolysis sequence for the diazoquinone 10.75 formed in the diazotization of 2-amino-1-naphthol. The product of the photolytic step is a ketocarbene (10.76), which undergoes a Wolff rearrangement to a ketene (10.77). In the presence of water in-dene-3-carboxylic acid (10.78) is formed this compound is highly soluble in water and can be removed in the development step. The mechanism given in Scheme 10-102 was not postulated as such by Stis, because in 1944 ketocarbenes were unknown (for a mechanistic discussion of such Wolff rearrangements see review by Zollinger, 1995, Sec. 8.6, and Andraos et al., 1994). 

Tsuda and Oikawa (1989) investigated the photolysis of the 1,2-isomer of 10.89 (1,2-benzoquinone diazide) by means of MINDO/3 molecular orbital calculations with configurational interaction. These authors came to the conclusion that no ketocarbene of the type of 10.90 is formed, but that the rearrangement into the cyclopentadienyl ketene 10.94 is a concerted reaction in which the elimination of nitrogen and the rearrangement take place simultaneously. In the opinion of the present author the theoretical result for 1,2-quinone diazide is not necessarily in contradiction to the experimental investigations of Sander, Yankelevich et al., and Nakamura et al., as the reagents used were not exactly the same. 

Laser flash photolysis (LFP) of quinone diazide 2d in Freon-113 at room temperature produces carbene Id, which could be monitored indirectly by addition of trapping reagents.25 At 2.0 xs the lifetime of Id is slightly longer than that of la (1.65 xs), otherwise the reactivities of these carbenes are very similar. The Id —> 11 rearrangement is not observed in the LFP experiments. All trapping products with a variety of reagents (O2, acetonitrile, pyridine etc.) are derived from carbene Id. 

The photolysis of benzo-annellated quinone diazides such as 2m should preferentially lead to products with intact benzene rings. Monochromatic irradiation... 

Photolysis of o-quinone diazides may be accompanied by dimer227- formation, e.g., in the case of CCVI and CCVII.270,271... 

The light-induced reaction of o-quinone diazides finds occasional use in the synthesis of a large number of compounds which are used in photography.273,277 Photolysis of diazoindauoues (CCVIII and CCX) provides a new synthetic route to cyclobutene carboxylic acid derivatives CCIX and CCXI, respectively.117 A good demonstration that ketenes are actually involved in the photodecomposition of o-quinone... 

Photosynthesis of azo-dyestuffs has been reported to be effected by the irradiation of o-quinone diazides. The reaction proceeds via the contraction of the diazide CCXV to the cyclic ketene CCXVI which adds water to form the eyclopentadiene carboxylic acid CCXYII. The latter couples with unchanged CCXV (obtained from 2-amino-l-phenol-4-sulfonic acid) to form the azo-dyestuff CCXVTII.270 Similarly, V-heterocyclic azo-dyestuffs, e.g., CCXX is obtained by the photolysis of CCXIX.275... 

The photolytic process of p-quinone diazides are of great interest since they establish a synthetic route for the preparation of a large number of phenolic compounds. CCXXII and CCXXIV are obtained on irradiation of p-quinone diazide (CCXXI) and imino-p-quinone diazide (CCXXIII) in the presence of primary alcohols,279 respectively photolysis of CCXXI in water produces hydroquinone.137 Another well-authenticated example of this reaction, is the photodecomposition of CCXXI and CCXXIII in the presence of benzene, and 2,6-dichloro-quinoneimine diazide-4 in the presence of pyridine to CCXXV, CCXXVI, and CCXXVII, respectively. 

The carbene mechanism of heterolytic dehalogenation of 4-chlorophenol was subsequently confirmed by studies using flash photolysis [21] and FT-EPR [22], A detailed account of the EPR measurements was published later [23], in which it was shown that the spin polarization of the phenoxyl-propanoyl radical pair produced in the photolysis of 4-chlorophenol in 2-propanol is consistent with a triplet state precursor. The proposition that this precursor is the above-mentioned carbene was proved by generating the same radical pair, with identical spin polarization, by photolysis of p-benzo-quinone diazide [22,23]. 

Carbena-cyclohexadienone (3). Photolysis or thermolysis of -quinone diazides (15) easily led to 3. The precursors of 3 are either />-aminophenols (14), -quinones (77) or anthrones (76). Diazotization of 14, Bamford-Stevens reaction of the tosyl-hydrazone of 77, or diazo-group transfer to 76 afforded the corresponding -quinonediazides 15 31-84)... 

Quinone diazides such as (104) are readily prepared by nitrosation of 4-aminophenols. On photolysis, (104) smoothly cyclizes to (105), a model for the antitumor antibiotic CC-1065 (equation 43). ... 

Carbenes, generated by photolysis of di- and tetrachloro-o-quinone diazides, react with oxetane in a 1 3 ratio to afford 15-membered crown ethers. Benzocrown ether 675 was obtained in 16% yield (91CB1865). Derivatives of macrocyclic crown ethers with four or five oxygen atoms in a ring were synthesized by Cu(acac)2-catalyzed cyclization of a,polyethylene glycols. 20-26-Membered crown-4(5) ethers 676 were prepared from the above-mentioned diazo ketones with tri- or tetra-ethylene glycols in 7-26% yields. Treatment of l,8-bis(diazoacetyl)octane with dodecane-l,12-diol under the same conditions results in a mixture of 52-membered tetraether 646 (40%) and compound 645 (81CC616). 

Visible light irradiation (X > 475 nm) of quinone diazide (21) isolated in Ar matrices at 10 K produces the corresponding carbene quantitatively. Further UV photolysis (X > 360 nm) of this carbene results in formation of a labile species, which is identified as the diradical (22). The identification of (22) was supported by ROSS-BLYP/6-31G(d,P) calculations, and confirmed by deuterium labelling. 

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