Most of the published bio-based benzoxazine research has focused almost entirely on various phenolic and amine compounds, while the aldehyde portion of the oxazine ring remains the same. These materials were classified as fully bio-based, even though only two of the three raw materials come from renewable raw materials. In this study, we synthesize a truly bio-based benzoxazine in which all three reactants required to synthesize a benzoxazine are from renewable sources for the first time. The organically produced compounds sesamol, furfurylamine and benzaldehyde are used to synthesize a truly bio-based benzoxazine through a solvent-free process. In contrast to almost all 1,3-benzoxazine resins described in the literature so far, the present publication reports on oxazine ring-substituted benzoxazines, which represents a great opportunity for the flexibility of the molecular design of benzoxazine resins compared to the already very rich variation of 1,3-benzoxazine compounds. The structure of 7- (furan-2-ylmethyl) -6,8-diphenyl-7,8-dihydro-6H.– -[1,3] Dioxolo[4′,5′:3,4] Benzo[1,2- e][1,3] Oxazine monomer is characterized by Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy, and 1D and 2D1Dog 13thC nuclear magnetic resonance spectroscopy. The polymerization behavior of the benzoxazine monomer is examined by differential scanning calorimetry (DSC), and the thermal stability of the polybenzoxazine is evaluated by thermogravimetric analysis (TGA). The corresponding polymer has a high thermal stability with 5% and 10% weight loss temperatures of 317 and 332 ° C., a char yield of 46% and a heat release capacity of 201 J g−1 k−1. Polymers that have a high char yield, a high decomposition temperature and a heat release capacity below 300 kJ g−1 are considered good anti-inflammatory materials.