Ozonolysis indenes

There are two syntheses of isoquinolines from indenes by oxidation and subsequent addition of ammonia or ammonium salts, differing only in oxidizing medium. Both are summarized in equation (76) in the first, ozonolysis with a reductive work-up is used (80JOC5312), in the second, periodate and catalytic amounts of osmium tetroxide (81JOC4999). The yields can be very good. 

There are several other examples of the use of indene derivatives as a source of isocoumarins. Alkaline decomposition of the cyclic peroxide (507), produced by ozonolysis of indene itself, yields a phenylacetaldehyde (57JA3165). Treatment of these aldehydes with acid gives access to isocoumarins which are unsubstituted in the pyranone ring (65JIC211). 

The acid has been formed by the reduction of 2-carboxyphenylacetaldehyde, itself available from indene by ozonolysis (57JA3165). This is one of the most convenient methods of synthesis of isochroman-l-one, which is obtained in a 70% overall yield from indene (Scheme 236), and has been used in the synthesis of isochromanones with specific deuterium labels <8ljcs(Pl)l685). 

Ochiai and coworkers have reported several useful oxidations employing the activated iodosylbenzene species in aqueous solution [30-34], The monomeric iodosylbenzene complex 18 in the presence of water can cleave the carbon-carbon double bond of indene 17 to form dialdehyde 19 (Scheme 6.10) [30]. Similar oxidative cleavage of various alkenes can be performed by using iodosylbenzene in water in the presence of HBF4. This convenient procedure provides a safe alternative to the ozonolysis of alkenes [30],... 

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