作者:Ronald Kowalewski、Paul Margaretha
DOI:10.1002/hlca.19930760311
日期:1993.5.12
6H-thiin-3-ones 1a–c with 3-chloroperbenzoic acid affords the corresponding 1-oxides 2a–c. On irradiation (350 nm) in either benzene or MeCN, these cyclic sulfoxides 2 isomerize to 3H, 7H-1,2-oxathiepin-4-ones 3. The tetramethyl derivative 3a is isolated by flash chromatography at −10°, but, at higher temperatures, it undergoes ring contraction and H2O elimination to give 4,4-dimethyl-2(2-methylprop-2enylidene)thietan-3-one
用3-氯过苯甲酸氧化2 H,6 H-硫辛3-酮1a - c得到相应的1-氧化物2a - c。在苯或MeCN中照射(350 nm)时,这些环状亚砜2异构化为3 H,7 H -1,2-氧杂噻吩-4-酮3。通过快速色谱在-10°分离四甲基衍生物3a,但在更高的温度下,它经历环收缩和H 2 O消除,得到4,4-二甲基-2(2-甲基丙-2-烯基)噻吨-3-酮(4)。Diemthyloxathiepinones 3b和3c在MeOH中进行环收缩,得到1-(4-甲基噻吩-2-基)乙酮(5)和两个非对映异构体4,4-二甲基-2-甲氧基-2-(1-甲氧基乙基)噻吨-3-酮(6和7)。