Vitisin B

Vitisin B (CAS 142449-90-9, C₅₆H₄₂O₁₂, MW 906.92 g/mol) is a resveratrol tetramer, also known as R-viniferin. It is the 3–8′ homocoupling product of two ε-viniferin radicals — the direct oxidative dimer of the dimer. Isolated from Vitis vinifera by Ito et al. The linear tetramer contains two dihydrobenzofuran units joined through 3–8′ bonds. Vitisin B is the biosynthetic precursor to vitisin A: acidic treatment effects quantitative cyclization to the more constrained vitisin A scaffold (Niwa et al., Tetrahedron, 2003, 59, 0000–0000; Keylor et al., Chem. Rev., 2015, 115, 8976–9027). Note: "vitisin B" also denotes an unrelated pyranoanthocyanin wine pigment. Specify CAS or compound class to avoid sourcing the wrong material.