Feng K, Mahdavi-Anary F, Partch R E, Li Y
Department of Chemistry, Clarkson University, Potsdam, NY 13699, USA.
Photochem Photobiol. 1995 Nov;62(5):813-7. doi: 10.1111/j.1751-1097.1995.tb09141.x.
Photochemical reactions of 6-azidocoumarin and 7-azido-4-methylcoumarin in the presence of secondary amines have been investigated for their potential applications in photoaffinity labeling. It was found that the singlet nitrene generated from 6-azidocoumarin isomerized to a dehydroazepine intermediate that reacted with an amine to yield two isomeric adducts. Photolysis of 7-azido-4-methylcoumarin, in contrast, gave a triplet nitrene that abstracted hydrogen atoms from secondary amine molecules to form 7-amino-4-methylcoumarin as the major product. The difference in the intersystem crossing rate between the two compounds originates from the azido position relative to the carbonyl group. Because of its ability to form a covalent linkage with a nucleophile, 6-azidocoumarin is deemed to have a greater potential as a photoaffinity label than 7-azido-4-methylcoumarin.
对6-叠氮基香豆素和7-叠氮基-4-甲基香豆素在仲胺存在下的光化学反应进行了研究，以探讨它们在光亲和标记中的潜在应用。研究发现，由6-叠氮基香豆素产生的单线态氮烯异构化为脱氢氮杂䓬中间体，该中间体与胺反应生成两种异构体加合物。相比之下，7-叠氮基-4-甲基香豆素的光解产生三线态氮烯，该三线态氮烯从仲胺分子中夺取氢原子，形成7-氨基-4-甲基香豆素作为主要产物。两种化合物系间窜越速率的差异源于叠氮基相对于羰基的位置。由于6-叠氮基香豆素能够与亲核试剂形成共价键，因此它被认为比7-叠氮基-4-甲基香豆素具有更大的光亲和标记潜力。
