2,2-Dimethyl-1,3-dioxane-4,6-dione → 2,2-Dimethyl-5-((thiophen-3-ylamino)methylene)-1,3-dioxane-4,6-dione

Reaction equation

[C:1](O)(=O)C(O)=O.[NH2:7][C:8]1[CH:12]=[CH:11][S:10][CH:9]=1.C(OC(OCC)OCC)C.[CH3:23][C:24]1([CH3:32])[O:29][C:28](=[O:30])[CH2:27][C:26](=[O:31])[O:25]1>>[CH3:23][C:24]1([CH3:32])[O:29][C:28](=[O:30])[C:27](=[CH:1][NH:7][C:8]2[CH:12]=[CH:11][S:10][CH:9]=2)[C:26](=[O:31])[O:25]1

Participants

Reactant 3

HCID 162492,2-Dimethyl-1,3-dioxane-4,6-dione

HCID 31214Ethyl orthoformate

HCID 22047570Thiophen-3-amine oxalate

Product 1

HCID 222500872,2-Dimethyl-5-((thiophen-3-ylamino)methylene)-1,3-dioxane-4,6-dioneYield 73.8%

Procedure

A 200-mL, rb flask equipped with a magnetic stirbar and a reflux condenser was charged with 3-aminothiophene oxalate (6.9 g, 36 mmol) and triethoxymethane (61 ml, 365 mmol) under N2. After stirring for 15 min, 2,2-dimethyl-1,3-dioxane-4,6-dione (5.3 g, 36 mmol) was added in one portion to the light brown slurry, and the mixture was heated to 85 deg C. in an oil bath overnight. The next day, a dark precipitate had formed and the mixture was cooled to ambient temp. The mixture was then cooled in an ice bath and the mixture was vacuum filtered through paper. The brown-red solids were washed with MTBE, air dried, then dried under vacuum to yield 2,2-dimethyl-5-((thiophen-3-ylamino)methylene)-1,3-dioxane-4,6-dione (6.73 g, 73% yield).