337514-13-3Relevant academic research and scientific papers
Dichotomy in the ring opening reaction of 5-[(2-furyl)methylidene]-2,2-dimethyl-1,3-dioxane-4,6-dione with cyclic secondary amines
Safar, Peter,Povazanec, Frantisek,Pronayova, Nad'a,Baran, Peter,Kickelbick, Guido,Kozisek, Jozef,Breza, Martin
, p. 1911 - 1938 (2000)
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-[(hexahydroazepine-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-4H-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-4H-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-4H-1,3-dioxin-6-olates (10).
Intra-molecular Diels-Alder reactions of citraconamic acids from furfurylamines and citraconic anhydride: Effects of substitution in the furan ring on regioselectivity
Murali, Rajappa,Surya Prakash Rao,Scheeren, Hans W
, p. 3165 - 3174 (2007/10/03)
Regioselectivity in the intra-molecular Diels-Alder (IMDA) reaction of furfurylcitraconamic acids derived from N-benzylfurfurylamines and citraconic anhydride can be controlled by substituents located in the furan ring and by reaction conditions. Reactions conducted under kinetic conditions resulted in cycloaddition products having methyl and aminomethylene substituent in 1,3-relationship whereas under thermodynamic conditions, excepting in the case of the 3-methylsulfanyl group, the products rearranged to more stable cycloadducts in which the substituents are in 1,2-relationship. Product formation can be explained on the basis of frontier orbital interactions and steric considerations.
