Studies on the synthesis of pentacyclic strychnos indole alkaloids. photocyclization of n-chloroacetyl-1,2,3,4,5,6-hexahydro-1,5-methanoazocino[4,3-b]indole derivatives
Abstract Photocyclization of 2-chloroacetyl-1,2,3,4,5,6-hexahydro-1, 5-methanoazocino[4,3-b]indole ( 5 ) takes place at the indole 4-position to give a 1 ,2 ,3 ,4 , 5 ,6-hexahydro-2 ,11-ethano-1 ,5-methanoazocino [4 , 3-6] indole system. Consequently, the method appears to be unsuitable for constructing the pyrrolidine ring of pentacyclic Strychnos indole alkaloids.
Functionalized 2-azabicyclo[3.3.1]nonanes. IV. synthesis of the indolo[3,2-f]morphan system.
Abstract A short route to the 2-azabicyclo[3.3.1]nonan-7-one system is described. Condensation of 4-piperidones with diethyl 2-oxopropylphosphonate, followed by catalytic hydrogenation furnished the corresponding piperidylpropanones 6 which were cyclized with mercuric acetate in acetic acid to the target target bicyclic ketones 1 . The Fischer indole synthesis from 1 a afforded regioselectively the indole [3,2-f]morphan 2 , a new heteromorphan type.
A novel synthesis of 2-aryl-4-piperidones by mannich cyclization of iminoketals
2-Aryl-4-piperidones have been synthesized by condensation between an aromatic aldehyde and a β-aminoketone ethylene ketal, and further cyclization of the resulting iminoketal with dry hydrogen chloride or anhydrous p-toluensulfonic acid. Alternatively, reaction of the above iminoketals with methyl fluorosulfonate followed by dry hydrogen chloride treatment and acid hydrolysis gives directly N-methyl-4-piperidones. The application of these reactions to the synthesis of some 2-aryl-3-acetylpyrrolidine systems is also described.