Studies on stable diazoalkanes as potential fluorogenic reagents. II. Ring-fused 4-diazomethylcoumarins.

Abstract

Several ring-fused 4-diazomethylcoumarins 4a-f were prepared as stable diazoalkanes, and their usefulness for the fluorescent labeling of acidic substances was examined. The most easily accessible product, 4-diazomethyl-2H-naphtho[1, 2-b]pyran-2-one 4a, reacted readily with carboxylic acids in the presence of silica gel catalyst, and also with alcohols in the presence of fluoroboric acid catalyst, to produce fluorescent esters and ethers in good yields.