Dihydrofuran ring opening in the reactions of 2,3- dihydrofuro[3,2-c]coumarin-3-one with arylhydrazines

Abstract

2,3 Dihydrofuro[3,2 c]coumarin 3 one reacts with arylhydrazines via two routes. The corresponding hydrazones are formed from arylhydrazines in alcohol and nitrophenylhydrazines in acetic acid or toluene. With phenylhydrazine and para tolylhydrazine in toluene, 2,3 dihydrofuro[3,2 c]coumarin 3 one reacts unusually undergoing dihydrofuran ring open ing and the formation of the corresponding 3 (2 imino 1 (2 arylhydrazinyl)ethylidene) chromane 2,4 diones. The solvatochromic properties of the synthesized compounds were studied using electronic absorption spectra and quantum chemical calculations.

15N labeling and analysis of13C–15N and1H–15N couplings in studies of the structures and chemical transformations of nitrogen heterocycles

“…51 The use of 15 N-phenylhydrazine 23*b in the reaction of 2,3dihydrofuro[3,2-c]coumarin-3-one 114 is another example of the use of labeled compounds to study chemical conversions in a series of heterocyclic compounds (Scheme 36). 52 The analysis of the 1 H-15 N coupling constants allowed the determination of the positions of the labeled atoms in product 118* and proved the mechanism of the transformation. In the proton spectrum of compound 118*, direct and long-range 1 H-15 N spin-spin interactions were detected for two signals of 15 NH-groups ( 1 J HN 89.7 Hz, 4 J HN $4 Hz and 1 J HN 93.4 Hz, 4 J HN $4 Hz).…”