A double oxidation procedure for the preparation of halogen-substituted para-benzoquinone monoketals: asymmetric synthesis of (−)-harveynone
摘要:
The double oxidation of halophenols with hypervalent iodine reagents in methanol provides a simple procedure to prepare halo-1,4-benzoquinone monoketals. Seven examples of this procedure are reported as is the conversion of 3-iodo-4,4-dimethoxycyclohexa-2,5-dienone into the natural product, (-)-harveynone. (C) 2010 Elsevier Ltd. All rights reserved.
new twist: A one‐pot nitrous acid free, diazonium‐free, and transition‐metal‐free variation of the Fischer indole synthesis has been developed. Condensation of quinone monoketals and aliphatic hydrazine hydrochlorides afforded indoles via intermediate alkylaryldiazenes. This method will complement the classical Fischer indole synthesis by providing indoles in two steps from widely available phenols
An unexpected nucleophilic chlorination of a quinone monoketal while carrying out a pyrazolidine synthesis has led to a general preparation of multisubstituted phenols. The products are obtained in good to high yields under mild conditions. The bridged pyrazolidines that were the original targets are obtained in the presence of a protic solvent.
The First Syntheses of (±)-SDEF 678 Metabolite and (±)-Speciosins A-C
作者:Daniel R. Hookins、Alan R. Burns、Richard J. K. Taylor
DOI:10.1002/ejoc.201001402
日期:2011.1
The epoxyquinone natural products SDEF 678metabolite, speciosin A, speciosin B and speciosin C have been prepared for the first time via a short synthetic route based around the palladium-catalysed coupling of a halogen-substituted 1,4-benzoquinone monoketal, a Diels–Alder/retro-Diels–Alder sequence and a diastereoselective epoxidation process.
环氧醌天然产物SDEF 678 代谢物、speciosin A、speciosin B 和 speciosin C 首次通过基于钯催化偶联的卤素取代的 1,4-苯醌单缩酮(Diels– Alder/retro-Diels-Alder 序列和非对映选择性环氧化过程。