86300-39-2Relevant academic research and scientific papers
Heterocyclic β-Enamino Esters, 30. Synthesis and Cycloaddition-Ring Expansion Sequence of Iminophosphoranes of Heterocyclic β-Enamino Esters: 6,7-Dihydrooxepins, thiepins, and 3,4-Dihydro-2H-thiocins
Wamhoff, Heinrich,Haffmanns, Guenter,Schmidt, Harald
, p. 1691 - 1707 (2007/10/02)
The heterocyclic β-enamino esters 1a - d, 2a - c, 5, and 6 react in the system triphenylphosphane/hexachloroethane/triethylamine in high yields to afford the resonance-stabilized iminophosphoranes 3a - d, 4a - c, 7, and 8.Alkyl iodides attack the electron rich C-β in 3a - d; the phosphonium salts 11a - h thus obtained split with alkaline into the imines 12a - h.With acetylenecarboxylic esters in a cycloaddition-ring expansion sequence from 3a - d, 4a - c, 7, and 8 dihydrooxepins 14a - h, 15a - c, e - g, dihydrothiepins 16a, b, and dihydro-2H-thiocins 17a, b, respectively, are formed in high yields.Acid-catalyzed hydrolysis of 14c, d leads to the enamino esters 19a, b.
