Photochemical Reactions of 5-Azido-8-methoxypsoralen

Irradiation of 5-azido-8-methoxypsoralen † in water–acetonitrile gives nitrenium ion and triplet nitrene transients, but only nitrenium ion products

“…The dilemma is that in all these solvents, the product is the quinone imine derived from the nitrenium ion. This is also true in methanol where there is a 97% yield 18 of the acetal 15 derived from solvent trapping of the nitrenium ion, . Note that in Fig.…”

“…The previous study of the products of irradiation of 10 in aqueous acetonitrile had involved a solution containing only 4 mol dm Ϫ3 water (~7 : 93 W-AN), and even here the yield of the quinone imine 17 was 93%. 18 To verify that 17 also forms with more water present, we employed as solvent 80 : 20 and 50 : 50 W-AN (as well checking in 10 : 90 W-AN). The product in each mixture is indeed 17, and it forms, within experimental error, in quantitative yield (95 ± 5%).…”

“…Experimental 5-Azido-8-methoxypsoralen 10 and 5-imino-5,8-dihydropsoralen-8-one 17 were available from a previous study. 18 The water-acetonitrile mixtures were prepared from doublydistilled deionized water and HPLC grade acetonitrile. Compositions provided in the text refer to ratios of volumes.…”

“…The compound of interest in this paper is 5-azido-8methoxypsoralen 10 (Scheme 2). In a previous paper, 18 Feng and Li reported that irradiation in methanol and ethanol resulted in high yields of the acetals 15 and 16. Acetonitrile containing 4 mol dm Ϫ3 water results in the quinone imine 17, presumably by way of the intermediate hemiacetal 14.…”

Plant coumarins: VII. Amination of oreoselone trifluoromethanesulfonate

“…Natural and synthetic aminocoumarins are promising from the viewpoint of medicinal chemistry for the design of new antibiotics and antitumor and antiviral agents [3]. Introduction of a nitrogen-containing functional group into psoralen molecule changes its phototoxicity and in some cases enhances photoantiproliferative activity [4]. Furthermore, extensive search for selective monoaminooxidase (MAO-A) inhibitors and antidepressants is performed in the series of amino-substituted furocoumarins [5,6].…”