Carboxylic esters, conjugated hydride

Nucleophilic addition to C=0 (contd.) ammonia derivs., 219 base catalysis, 204, 207, 212, 216, 226 benzoin condensation, 231 bisulphite anion, 207, 213 Cannizzaro reaction, 216 carbanions, 221-234 Claisen ester condensation, 229 Claisen-Schmidt reaction, 226 conjugate, 200, 213 cyanide ion, 212 Dieckmann reaction, 230 electronic effects in, 205, 208, 226 electrons, 217 Grignard reagents, 221, 235 halide ion, 214 hydration, 207 hydride ion, 214 hydrogen bonding in, 204, 209 in carboxylic derivs., 236-244 intermediates in, 50, 219 intramolecular, 217, 232 irreversible, 215, 222 Knoevenagel reaction, 228 Lewis acids in, 204, 222 Meerwein-Ponndorf reaction, 215 MejSiCN, 213 nitroalkanes, 226 Perkin reaction, 227 pH and, 204, 208, 219 protection, 211... 

Normally, esters beta to a radical are perfectly stable and do not furnish olefins and carboxyl radicals.6 This is true even for 1 where tin hydride reduction affords only 2. Clearly, conjugation with two phenyls is not a sufficient driving force for elimination. However, the driving force in the change from dihydrophenanthrene to phenanthrene would be greater and in... 

Carboxylic Acids and their Derivatives.—2,3-Seco-A -unsaturated dicarboxylic acids (443), obtained by ozonolysis of 2-hydroxymethylene-4-en-3-ones, have been considered rather resistant to cyclisation to form the A-nor-3-en-2-one system (444). Two convenient methods for achieving such a reaction are now described. Dieckmann condensation of the dimethyl ester (445) was successful with sodium hydride, in toluene containing a little methanol. The 5-methoxy-carbanion (446), resulting from conjugate addition of methoxide ion, is suggested as a possible activated intermediate. Alternatively, the diacid (in the B-nor-series)... 

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