1.2- Dimethyl-1 -carboxymethyl-2-phenyl

Perhaps the most useful of these 4,5-dihydro-I/7-pyrazole based routes, however, are those where the intermediate is simply oxidized with manganese(IV) oxide. As in the synthesis of 3,3-dimethyl-l-nitro-2-phenylcyclopropene (5), this sometimes makes possible the synthesis of precursors not available by the diazoalkane to acetylene addition route. In other cases, man-ganese(IV) oxide oxidation gives yields which are at least as good and often better than the diazoalkane to acetylene addition route and this method has been applied to the synthesis of nitro-, cyano-, carboxymethyl-, phenyl-, and alkyl-substituted systems. ... 

Ethyl l-carboxymethyl-5,7-dimethyl-4-oxo-3-phenyl-3,4-dihydio-6-phthalazinecarboxylate 178-180, MS, NMR 956... 

Ethanaminium, N-(4-(bis(4-(diethylamino) phenyl) methylene)-2,5-cyclohexadien-1-ylidene)-N-ethyl-, chloride. See Basic violet 4 1-Ethanaminium, N-(carboxymethyl)-N,N-dimethyl-2-[(1-oxococo alkyl) amino]-, hydroxides, inner salt. See Cocamidoethyl betaine... 

The extent of the reaction is very much governed by the size of the alkynic substituents (Scheme 5) for example, if both substituents are bulky tert-butyl groups, no oligomerization occurs and only the 1 1 alkyne complex is formedJ When one tert-butyl is replaced by the smaller phenyl substituent, dimerization takes place and the cyclobutadiene complex is the only productJ However, diphenyl acetylene gives a mixture of the cyclobutadiene complex and the benzenoid trimerP The somewhat smaller carboxymethyl groups ensure that dimethyl acetylene dicarboxylate gives only the trimer.t ... 

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