Photorearrangement continued

These data demonstrate that a photorearrangement reaction of 1-alkoxy group actually occurs. We continue to speculate that any substituents at the 1 position of indoles may migrate to 3, 4, and/or 6 positions upon photoirradiation. 

The photorearrangement of azoxybenzenes to hydrazobenzenes is a well-studied process but one which continues to attract attention. The reaction has now been studied for methoxy and... 

No reports of any significance have been published on the photochemistry of nitrones during the year. Further investigations on the photorearrangement of heteroaromatic N-oxides and related systems have, however, been described in the literature. Debate on the possible intermediacy of oxaziridines in these transformations continues. A study of the effect of a magnetic field on the photorearrangement of isoquinoline N-oxide (60) in ethanol indicates that conversion into the lactam (61) does not... 

The photoisomerization of azo-compounds continues to attract attention. Evidence that photoisomerization of certain steroidal-substituted azo-compounds proceeds by way of an inversion mechanism has been described. Full details have now been reported of the photorearrangement of l,2-diaza-(Z)-cyclo-oct-l-ene (14) to the -isomer (15), and analogous transformations have been observed... 

The photocycloaddition chemistry of pyridines substituted with electron-donor and electron-acceptor groups at the 2- and 3- positions continues to be exploited. The results of irradiation of such pyridines in the presence of 2-cyanofuran have now been described. The yields of the (47r+47r) cycloadducts (29) and (30), the pyridine dimer (31) and the transposition isomer (32) are dependent on the level of methyl substitution on the heteroarene and are given in Scheme 2. Other photocycloadditions to heteroarenes reported within the year include the reactions of benzodithiophene (33) with butadiyne derivatives and dimethyl acetylene dicarboxylate, giving low yields of (34) and (35) respectively, the latter from photorearrangement of the primary adduct (36). The (271+471) photocycloaddition of indoles (37) to cyclohexa-1,3-dienes (38) is sensitized by the aromatic ketones (39), and yields (14-46%) of the exo and endo isomers of the adduct (40) in ratios which are dependent on the substituents on the addends. 

Photochemical Reactions.—Mazzocchi and Lustig have continued their studies on the photorearrangement of substituted cyclopropanes to propenes by hydrogen migra-... 

Naphthalenequinone methides (382) and (384) were photochemically synthesized from 1- and 2-adamantylnaphthol derivatives (381) and (383), respectively (Scheme 82). Photorearrangement of allqrl-aryl nitrones (385) via oxaziridines (386) afforded amide derivatives (387) as peptide fragments via continuous flow process (Scheme 83). ... 

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