作者:Xiao-Lan Duan、Ross Perrins、Charles W. Rees
DOI:10.1039/a700358g
日期:——
Trithiazyl trichloride 1 converts 2,5-diphenylfuran into
5-benzoyl-3-phenylisothiazole 2 regiospecifically and in high yield.
This is a new ring opening of furans and a new synthesis of
isothiazoles. 2,5-Bis(4-methylphenyl)furan, 3-bromo-2,5-diphenylfuran,
2,3,5-triphenylfuran, 2,5-di-tert-butylfuran and its 3-chloro
and 3-bromo derivatives react in an entirely analogous manner to give
the corresponding isothiazoles (55–85%) in synthetically useful,
one-pot, conversions. 2,5-Diphenylthiophene reacts more slowly with the
trimer 1 to give the same product, 2, as the corresponding furan,
probably by oxidation of the analogous thiobenzoyl compound by the
reagent, which is shown to oxidise thiobenzophenone to benzophenone very
rapidly. Tetraphenylcyclopentadienone 8 reacts rapidly with the trimer
to give 3,4,5,6-tetraphenyl-2(1H)-pyridone 10 (56%). Possible
mechanisms in which the monomer, Cl–SN, is the reacting
species are proposed for all of these reactions.
三氮化氯化物1使2,5-二苯基呋喃转化为具有区域选择性和高得率的5-苯甲酰-3-苯基异噻唑2。这是呋喃的新环开化和异噻唑的新合成。2,5-双(4-甲基苯基)呋喃、3-溴-2,5-二苯基呋喃、2,3,5-三苯基呋喃、2,5-二叔丁基呋喃及其3-氯和3-溴衍生物以完全类似的方式反应,生成相应的异噻唑(55-85%),实现合成上有用的一锅法转化。2,5-二苯基噻吩与三聚物1的反应速度较慢,生成相同的产物2,可能是由于该试剂对类似的噻苯乙酰化合物的氧化,已证明其能迅速将噻苯基酮氧化为苯基酮。四苯基环戊二烯酮8与三聚物迅速反应,生成3,4,5,6-四苯基-2(1H)-吡啶酮10(56%)。对于所有这些反应,提出了单体Cl–SN作为反应物种的可能机制。