Diazo 1,3 indandione

The products formed in these reactions are very sensitive to the functionality on the carbenoid. A study of Schechter and coworkers132 using 2-diazo-1,3-indandione (152) nicely illustrates this point. The resulting carbenoid would be expected to be more electrophilic than the one generated from alkyl diazoacetate and consequently ihodium(II) acetate could be used as catalyst. The alkylation products (153) were formed in high yields without any evidence of cycloheptatrienes (Scheme 33). As can be seen in the case for anisole, the reaction was much more selective than the rhodium(II)-catalyzed decomposition of ethyl diazoacetate (Scheme 31), resulting in the exclusive formation of the para product. Application of this alkylation process to the synthesis of a novel p-quinodimethane has been reported.133 Similar alkylation products were formed when dimethyl diazomalonate was decomposed in the presence of aromatic systems, but as these earlier studies134 were carried out either photochemically or by copper catalysis, side reactions also occurred, as can be seen in the reaction with toluene (equation 36). 

Banks, J. T., Scaiano, J. C., Laser Drop and Low Intensity Photolysis of 2 Diazo 1,3 Indandione Evidence for a Propadienone Intermediate, J. Photochem. Photobiol. A 1996,96,... 

The mechanism of the ketene-alcohol addition reaction depends on the reaction conditions. A time-resolved UV-VIS (TRUV-VIS) study has shown that, under normal photolysis conditions, 2-diazo-1,3-indandione (1) in alcohols forms diester 4 via the secondary photolysis of ester 3. However, under laser drop photolysis conditions, where the laser intensity is very high, the formation of diester 4 occurs via intermediate 5 (Scheme 2). 

The rhodium-catalyzed CH insertion reaction of the diazo compound 1188 affords 1,3-indandione 1189, the enol tautomer 1190 of which undergoes ring expansion furnishing the six-membered ring dipole 1191 which dimerizes, even in the presence of excess DMAD to produce an unusual isochroman-4-one 1192 (Scheme 294)... 

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