William S. Murphy

Regiospecific synthesis of mitosenes by a new bromoquinone-enamine annulation reaction

Abstract A facile new one pot annulation of monobromoquinones 7 to the vinylogous carbamate 3 provides a direct route to the pyrroloindoloquinone framework. Synthesis was extended to 7-methoxymitosene 2 ( R = OMe, R 1 = R 2 = 11). The mechanism of the annulation was elucidated.

[2+2]- and [3+2]- cycloadditions of allylsilane to quinones: Divergence from the sakurai reaction

Abstract Naphthoquinone 1 reacts with allyltrimethylsilane in the presence of Me2AlCl at 78°C to yield a mixture of the [2+2]- and [2+3]- cycloadducts, 2 and 3. When the cyclobutane 2 was treated with Me2AlCl it rearranged stereospecifically to the cyclopentane 3.

Regioselective synthesis of the kinamycin ABCD ring system

Abstract The new bromoquinone-enamine annulation was successfully extended to acyclic enamino ketones resulting in a new synthesis of the ABC framework 6 of kinamycins and when applied to cyclic enamino ketones 8a–e the first synthesis of their ABCD ring system. Smooth aromatisation of compounds 4b,d to 9a,b respectively was effected with DDQ.

Total synthesis of (±)-picropodophyllone

Following model studies, the synthesis of (±)-picropodophyllone was completed by first cyclopropanating the appropriate chalcone (11) with ethoxycarbonyl dimethylsulphonium methylide. Treatment of the resulting cyclopropyl ketone with stannic chloride in either benzene or methylene chloride failed but in nitromethane the tetralone (1Oa) was formed. The lactose ring was completed using formaldehyde with an overall yield based on chalcone of 40%.

A new cyclisation involving cyclopropyl ketones. A short route to 1-aryltetralones.

Abstract Activated aryl aroylcyclopropanes cyclise with Lewis acids under mild conditions to 1-aryltetralones.

Reductive cleavage of cyclopropyl ketones

Abstract Aryl substituted cyclopropyl ketones are cleaved to acyclic ketones with zinc and zinc chloride or with zinc alone in refluxing alcohol.

REGIOSPECIFIC FREE RADICAL ANNULATION REACTIONS OF DIETHYLBENZYLMALONATE WITH UNSYMMETRICAL 1,4-NAPHTHOQUINONES : A DIRECT APPROACH TO RING A AROMATIC ANGUCYCLINONES

Abstract The regiospecific formation of the C-8 oxygenated benz[a]anthraquinones was achieved by a bromine directed Mn (III) initiated oxidative free radical reaction of diethylbenzylmalonate (DBM) with quinones. The regioisomeric benz[a]anthraquinone was obtained when the isomeric quinone was employed. The novel Mn(OAc) 3 induced C - benzylation of bromoquinones with diethylbenzylmalonate is described.

Lithium keten thioacetalides. Factors influencing α-versusγ-alkylation

Alkylation of the lithium salt of the vinyl-1,3-dithian (2; R = CH3) occurred exclusively at the α-carbon. However both α- and γ-alkylation was observed with the substrate (2; R = C6H5). A systematic investigation revealed that the α : γ ratio is correlated with the hardness of both the leaving group and the alkyl group of the alkylating agent. An occasionally formed side-product from the reactions of (2; R = C6H5) was the α,γ-dimer (11) of the anion (6; R = C6H5).

A serendipitous route to the benzidene nucleus. Structural elucidation by noeds.

Abstract The epimeric indenones (3) and (4) are readily synthesised and rapidly formed by treating bis( p -methoxyphenylcyclopropyl) ketone (2) with stannic chloride in nitromethane. The structure of (3) was determined by X-ray crystallography and that of (4) by NOEDS.

Novel alkylaluminium chloride promoted [2+2] cycloaddition reactions of styrenes with 1,4-naphthoquinones and bromoquinones: A facile route to orthoquinodimethane precursors

Abstract The first examples of a Lewis acid catalysed [2+2]cycloaddition between styrenes and naphthoquinones have been observed. The reactions of both methoxyl and acetoxylnaphthoquinones were both regio- and stereospecific. When m -methoxystyrene was employed a novel tetracycle was also formed, and by an unexpected mechanistic pathway. Extension to bromoquinones resulted ultimately in the formation of arylnaphthocyclobutenes, common precursors of the orthoquinodimethanes.