reported earlier. Obviously, the alkyl groups at the 4-positions of the 4 H -thiopyrans strongly diminish the efficiency of the di-π-methane rearrangement and, contrastingly, a four-electron suprafacial [1,3]-sigmatropic rearrangement is found to be highly efficient.
研究了4,4-二烷基-2,6
-二苯基-4 H-
噻喃和4-苄基-2,4,6-三苯基-4 H-
噻喃的光异构化, 并将其与2,4,4进行了比较,先前报道了6-四芳基-和4-烷基-2,4,6-三芳基-4 H-
噻喃类似物。显然,在4 H-
硫吡喃的4位上的烷基 大大降低了二π-
甲烷重排的效率,相反,发现四电子超表面[1,3]-σ重排高效。