(Chemical Equation Presented) Under acetylating conditions racemic thioflavanone thiosemicarbazones cyclize into racemic 3-acetylspiro[1,3,4- thiadiazoline-2,4′-thioflavans] and a racemic 3-acetylspiro[1,3,4- oxadiazoline-2,4′-thioflavan] with trans O(1) or S(1) and Ph(2′eq). Hindered rotation of the endocyclic N(3) acetyl group spirothiadiazolines caused the formation of isomers separable by HPLC. X-ray diffraction analyses, 1H-, 13C-, and 15N NMR measurements as well as MOPAC QM calculations were performed to reveal the structures of these isomers.
ASJC Scopus subject areas
- Organic Chemistry