1.1.3.3- Tetramethyl-2-indanone

Nitric oxide can be scavenged as a stable, ESR-detectable free radical by a quinodimethane intermediate, l,2-disopropylidene-3,5-cyclohexadiene, which can be generated by photolysis of l,l,3,3-tetramethyl-2-indanone. This approach offers the possibility of detecting and possibly quantitating NO produced by biological systems [24]. Free NO in solution is not detectable by ESR. 

Carbonyl and thiocarbonyl complexes of Mes2Si have been observed in a remarkable series of experiments by Ando and coworkers144. Photolysis of Mes2Si(SiMe3)2 was carried out at 77 K in a soft (3-MP/isopentane) matrix in the presence of tetramethyl-2-indanone or its sulfur analog. The free silylene was formed initially but it slowly reacted with the carbonyl (or thiocarbonyl) compound to give the complex, which can be formulated as a silacarbonyl ylide (Scheme 8). Further photolysis converted these ylide complexes to the silaoxirane or silathiirane, reversibly. 

Analogous decarbonylations have been observed for ketones under ultraviolet irradiation at elevated temperatures. From a preparative point of view the behavior of diphenyl-substituted and a,a-divinyl-substituted ketones is interesting, as they are decarbonylated when their benzene solutions are subjected to ultraviolet irradiation.69 This favorable effect of phenyl sub-stitutents on decarbonylation has been noted also for cyclic ketones for example, under suitable conditions l-phenyl-2-indanone eliminates carbon monoxide and yields 90% of 5,6,ll,12-tetrahydro-5,6-diphenyldibenzo[a,e]-cyclooctene as a mixture of cis- and trans-forms,10 whereas 2-indanone itself is hardly decarbonylated at all in benzene solution. That in other cases decarbonylation is usually more profitable in the gas than in the liquid phase is shown by studies of the photolysis of tetramethyl-l,3-cyclobutanedione which in the gas phase gives 2 equivalents of carbon monoxide and a quantitative yield of 2,3-dimethyl-2-butene.71... 

Alkylation of Ketones. Ketones can be permethylated with iodomethane in DMSO containing solid KOH. Cyclobutanone, cyclopentanone, and indanone gave the corresponding tetramethyl ketones in 49, 90, and 75% yields, respectively. All reagents can be used without drying and KOH can be used as pellets or as a powder. ... 

Phenyl-3-heptyn-2-ol, P-60107 l,l,3,3-Tetramethyl-2-indanone, T-60143 8,10-Tridecadiene-4,6-diyn-1 -ol, T-80249... 

Using matrix isolation techniques, we obtained the first spectroscopic evidence for the intermediacy of the hitherto unknown silacarbonyl and silathiocarbonyl yUdes in a low temperature matrix. Irradiation of the oxasUirane (75a) in an isopentane/3-methylpentane (Ip/3-Mp) matrix at 77 K with a low-pressure mercury lamp led to the appearance of a new band at 610 nm in the UV-vis spectrum and the matrix became interestingly blue in color. This absorption band was stable at 77 K on prolonged standing. However, it immediately disappeared on brief irradiation with a Xenon lamp (X >460 nm) or when the matrix was allowed to melt. This colored species was independently generated by the reaction of dimesitylsilylene with l,l,3,3-tetramethyl-2-indanone (76a). Furthermore, irradiation of 2,2-dimesitylhexamethyltrisUane in the presence of 76a in IP/3-MP at 77 K... 

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