Atkins Jeffery M, Vedejs Edwin
Department of Chemistry, University of Michigan, Ann Arbor, 48109, USA.
Org Lett. 2005 Jul 21;7(15):3351-4. doi: 10.1021/ol051244x.
[reaction: see text]. Methodology has been developed to prepare bis-oxazoles via a two-stage iterative process. The sequence begins with C(2)-chlorination of a lithiated oxazole using hexachloroethane. Generation of the C(2)-C(4)(') bond by S(N)Ar substitution with TosMIC anion, followed by conversion to the heterocycle in a one-pot reaction with glyoxylic acid monohydrate, affords the desired bis-oxazole in good yield and purity. The two-stage process allows for efficient synthesis of a tris-oxazole and the first iterative preparation of a tetra-oxazole.
[反应：见正文]。已经开发出通过两步迭代过程制备双恶唑的方法。该序列始于使用六氯乙烷对锂化恶唑进行C(2)-氯化。通过用TosMIC阴离子进行S(N)Ar取代生成C(2)-C(4)(')键，然后在与一水合乙醛酸的一锅反应中转化为杂环，以良好的产率和纯度得到所需的双恶唑。该两步过程允许高效合成三恶唑以及首次迭代制备四恶唑。
