497163-39-0Relevant articles and documents
Bis(lactone)-annulated 4H-pyranes and 1,4-dihydropyridines from 3,3′-(nitrobenzylidene)-bistetronic acids
Goerlitzer,Trittrmacher,Bartke
, p. 606 - 609 (2007/10/03)
The bistetronic derivatives 4, obtained by base catalyzed reaction of the aldehydes 3 with surplus tetronic acid (2), cyclize in polyphosphoric acid (PPA) to yield the 4H-pyranes 5. The amino derivative 6 formed by reduction of the nitro group of 5a easily splits to give the furoquinoline 7 and 2. By heating the ammonium bistetronate 8 ring closure occurs leading to the bisannulated 1,4-dihydropyridine (DHP) 9. The DHP 9 is dehydrogenated to the corresponding pyridine 10. The half wave potentials of the 4H-pyranes 5 and 6 as well as the 1,4-DHP 9 are determined by differential pulse voltammetry.