Indenones

Interesting formation of the fulvene 422 takes place by the reaction of the alkenyl bromide 421 with a disubstituted alkyne[288]. The indenone 425 is prepared by the reaction of o-iodobenzaldehyde (423) with internal alkyne. The intermediate 424 is formed by oxidative addition of the C—H bond of the aldehyde and its reductive elimination affords the enone 425(289,290]. 

Carbonylation of halides in the presence of terminal and internal alkynes produces a variety of products. The substituted indenone 564 is formed by the reaction of o-diiodobenzene. alkyne, and CO in the presence of Zn[414]. 

Hsynthesis from, 3, 767 Indenobenzazepines pharmacological properties, 7, 546 Indenone oxide, 2,3-diphenyl-photochromic compound, 1, 385 In deno[ 1,2-c][ 1,2,4]triazines synthesis, 3, 434 Indicated hydrogen nomenclature, 1, 33 Indigo, I, 317, 318-319, 4, 370 Baeyer synthesis, 1, 319 colour and constitution, 1, 344-345 molecular structure, 4, 162 photochromic compound, 1, 386 synthesis, 4, 247 Indigoid dyes... 

When indene (4) is brominated in carbon tetrachloride, it gives some syn addition ( 15%), but indenone (5) gives only anti addition under the same conditions. 

Using 3-substituted cyclohexanones the /rans-diastereoselective synthesis of decalones and octahydro-1 //-indenones may be achieved 164 169. This method has been applied, for instance, in the synthesis of 19-norsteroids. In a related Michael addition the lithium enolate of (R)-5-trimethylsilyl-2-cyclohexenone reacts with methyl 2-propenoate selectively tram to the trimethylsilyl substituent. Subsequent intramolecular ring closure provides a single enantiomer of the bicyclo[2.2.2]octane170 (see also Section 1.5.2.4.4.). 

This type of 1,4-addition reaction has also been applied to optically active indenone derivatives in the synthesis of enantiomerically pure (C/D)-frmw-dihydro-l.f/-indenones, precursors for nortestosterone281 see also refs 282, 283 and 397. 

Another interesting [3+2] cycloaddition in aqueous media was recently reported by Murakami.131 2-Cyanophenylboronic acid reacted as a three-carbon component with alkynes or alkenes to afford substituted indenones or indanones (Eq. 4.67). The use of an alkynoate even produced benzotropone, a formal [3 + 2 + 2] adduct. 

During the synthesis of an indenone derivative, Hoomaert found that AICI3 catalyzed the dimerization of indenone 34 to form truxone 35 (Scheme 2.3) [23]. Attempts to... 

Ishikawa and coworkers reported a synthesis of ( )-0-methylkinamycin C (54) [32, 33]. Their retrosynthetic analysis is shown in Scheme 3.9. It was envisioned that 54 could be derived from the dihydroindanone 55 by D-ring oxygenation, installation of the diazo substituent, and oxidation of the protected hydroquinone function. The dihydroindanone 55 was envisioned to arise from the enol ether 56, itself formed from an endo Diels-Alder reaction between the indenone 59 and the diene 58. 

The key Diels-Alder cycloaddition was effected by treating a mixture of the indenone 59 and the diene 58 with zinc chloride in dichloromethane at —15 °C (Scheme 3.11). Under these conditions, the expected endo-adduct 56 was formed. 

Thermal reactions of N-aryl cyclopropenone imines 268 are differentiated by the nature of the N-aryl substituent. Imines 268 (Ar = phenyl, p-nitro-phenyl) undergo isomerization to N-aryl-2-phenyl-indenone imines 271 when heated in aprotic solvents202. Since in protic solvents, e.g. ethanol, only the iminoester 272 is isolated, evidence seems to be given for the intermediacy of 269 implying carbene and ketene imine functionality, which may either cause electrophilic ring closure with a phenyl group to form 271 or may add to the hydroxylic solvent (272). 

Irradiation of diphenyl N(p-nitrophenyl) cyclopropenone imine (268) gave, in a clear-cut photoreaction, the phenanthreno indenone imine 275170) resulting from two units of 268 by loss of two hydrogens and p-nitrophenyl isocyanide the mechanism of this transformation has not yet been elucidated. 

Whilst Lewis acids like SbCls or A1C13 form stable adducts with diphenyl cyclopropenone, from which the ketone can be regenerated unchanged208, trialkyl boranes effect a remarkable ring expansion to 2-phenyl indenone derivatives 309 containing an additional residue in the 3-position215. ... 

Since the 3-substituent may originate from borane as well as from the solvent [e.g. with triisopropyl borane in diethyl ether indenones 309 were obtained with... 

Diels-Alder reactions with acyclic and carbocyclic dienes are compiled in Scheme 5. The comparison between the Lewis-acid catalyzed and pressure-induced reaction (entry 1) shows that the application of high pressure, particularly in acid-sensitive systems, can sometimes lead to a better yield. Furthermore, pressure may shift the product ratio, if the activation volumes of the competing reactions are different, so that the application of pressure may also be useful in highly reactive systems, e.g. the reactive indenone 17 as dienophile, provided that a shift in the product ratio is desired. At atmospheric... 

In a total synthesis of coriandrin 68, the isocoumarin unit is generated by the thermal rearrangement of an indenone epoxide 67, the first application of a cycloreversion route to isocoumarin synthesis (Scheme 46) <00TL3677>. 

Indenones can be synthesized from the carbonylation of aromatic imines (Equation (111)).102... 

The reaction of 2-formyl- and 2-acetylarylpalladium(n) bromide complexes 201 with internal alkynes and TIOTf affords indenols at room temperature, whereas cationic 2-formylarylpalladium(ll) pyridine complexes 202 do not react with alkynes at room temperature but afford indenones at 90 °C (Scheme 94). 

Attempts to improve the DUV sensitivity of PMMA have spawned a variety of new DUV resist materials. Notable among these are copolymers of methyl methacrylate and indenone (80) which are reported to provide positive-tone resist function at 20 to 60 mJicnP in the DUV and copolymers of methyl methacrylate and 3-oximino-2-butanone (81). The latter materials provide a substantial increase in sensitivity over PMMA and are capable of 1 micron resolution. 

Thermolysis of indenone oxides (151) is an equally useful route to the betaines (150). Dimethyl acetylenedicarboxylate and compound 151 (R = R = Ph) at 175°C give adduct 153, and cyclohexanone at 150 C gives adduct 154. - Similarly, 1,3-dipolar adducts (e.g., 155) have been obtained using a wide variety of olefins—including cis- and [rans-, 2-dichloroethylene, dimethyl maleate, dimethyl fumarate, maleic anhydride, cis- and tran -stilbene, fran -dibenzoylethylene, tra .y-l,2-dicyanoethylene, A -phenylmaleimide, vinylene carbonate, acenaphthylene, and norbor-nadiene. With cis olefins the endo adduct (155) is usually the predominant isomer. Diphenylcyclopropenone gives compound 156 by spontaneous elimination of carbon monoxide from the initial adduct (157). Adduct 156... 

Further examples of these betaines (150) have been prepared by photolysis of indenone oxides (151). ... 

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