P. Šafár̆, F. Považanec, N. Prónayová
2000
Citations
0
Influential Citations
13
Citations
Journal
Collection of Czechoslovak Chemical Communications
Abstract
5-[(2-Furyl)methylidene]-2,2-dimethyl-1,3-dioxane-4,6-dione ( 1a ) treated with equimolar amount of pyrrolidine or hexahydroazepine afforded 5-(pyrrolidine)- ( 2a ) or 5-[(hexahydro- azepine-1-yl)-2-hydroxypenta-2,4-dien-1-ylidene]-2,2-dimethyl-1,3-dioxane-4,6-dione ( 2d ). Their treatment with hydrobromic acid led to cyclization and formation of stable 5-cyclopentenyl-4 H -1,3-dioxine hydrobromides ( 3a , 3d ). Under the same conditions 1a treated with morpholine or piperidine yielded a mixture of 2b , 3b and 2c , 3c , respectively. The corresponding 3-substituted furans 1b - 1e gave only substituted 5-cyclopentenyl-4 H -1,3-dioxines ( 3e - 3i ). The use of an excess amine in reaction with 1a yielded unexpectedly 5-(3,5-dihetaryl-cyclopent-2-en-1-ylidene)-2,2-dimethyl-1,3-dioxane-4,6-diones ( 9a-9c ) and 5-[5-hexahydroazepin-1-ium-1-ylidene-2-(hexahydroazepin-1-yl)cyclopent-1-en-1-yl]-2,2-dimethyl-4-oxo-4 H -1,3-dioxin-6-olates ( 10 ).