Schopf reaction

Keto-piperidine from cyclic imine and P-ketoacetate. 

Jarevang, T. Anke, H. Anke, T. Erkel, G. Sterner, O. Acta Chem. Scand. 1998, 52, 1350. 

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While mechanistically this reaction is related to the Robinson-Schopf reaction for the generation of the tropinone skeleton, it also has similarities to the Hantzsch reaction. Here the heterocyclic ring 75 is assembled by the condensation of an equivalent of acetonedicarboxylic ester 72 with 2 equivalents of aldehyde 73 in the presence of ammonia or primary amine 74. 

Stevens and Lee (28) have reported an elegant synthesis of coccinelline (69). Treatment of 66 at pH=l gave intermediate 67 which was then treated with dimethyl acetone dicarboxylate at pH=5.5 to give a single tricyclic isomer, the ketodiester 68, in 75% yield. Compound 68 was then converted into coccinelline (59). This result shows that the Robinson-Schopf reaction (29, 30) can take place with a remarkable control of stereochemistry. 

Robinson-Schopf reaction. Synthesis of tro-pinones from a dialdehyde, methylamine, and aceto-nedicarboxylic acid. 

This reaction was first reported by Robinson in 1917 and subsequently improved by Schopf in 1935. It is an ingenious one-pot multicomponent synthesis of tropinone from succindialdehyde, acetonedicarboxylic acid and methylamine in aqueous solution involving a double Mannich Reaction This reaction is thus known as the Robinson tropinone synthesis," Robinson synthesis, " Robinson-Schopf reaction,Robinson-Schopf condensation, or Robinson condensation." It has been reported that the Robinson tropinone synthesis can take place without any racemization at the stereogenic center adjacent to the aldehyde group, as demonstrated by the formation of L-a/to-teloidinone from D-tartaraldehyde, and c-a/to-teloidinone from i-tartaraldehyde respectively." ... 

Robinson Annulation Robinson-Schopf Reaction Rosenmund Reduction Rosenmund-von Braun Synthesis Rothemund Reaction Rubottom Oxidation Ruff-Fenton Degradation Rupe Rearrangement Ruzicka Large Ring Synthesis Sabatier-Senderens Reduction Sachs (see Ehrlich-Sachs Reaction)... 

Schollkopf Bis-Lactim Amino Acid Synthesis Schopf (see Robinson-Schopf Reaction)... 

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