Francis Johnson

The structure of “siliriness” and “germireness”

Abstract The compounds reported recently by Russian workers as unsaturated three-membered heterocyclic ring containing silicon or geranium are shown to be, in fact, derivatives of the novel ring systems 1,4-disilin and 1,4-digermin.

Heterocyclic Syntheses Involving Nitrilium Salts and Nitriles under Acidic Conditions

Publisher Summary This chapter helps in understanding the reactions involving nucleophilic attack on the nitrile function itself. The attack takes place on the carbon atom of the nitrile group, by virtue of the latters high dipole moment. Three types of reactions are discussed: (a) the Ritter reaction, (b) reactions involving nitrilium salts, and (c) α,ω -dinitrile cyclizations. The heterocyclic syntheses that can be accomplished using a mononitrile are of the more conventional type where, generally, two organic components are combined to produce the ring. The first of these approaches stems from the Ritter reaction, whereas the second utilizes nitrilium salt intermediates. The most useful application of the Ritter reaction in heterocyclic synthesis appears to be the preparation of 1-pyrroline. These materials can be obtained simply and in good yield from 1,4-glycols, with the limitation that R must be an alkyl (or aryl) group rather than hydrogen for good yields.

The conversion of 2,x-disubstituted cyclohexanones to their less stable isomers—the stereochemical implications of enamine hydrolysis☆

Abstract When 2-methyl-x-alkylcyclohexanones (x≠2) are converted to their enamines and the latter are hydrolysed under kinetic conditions the process leads to a substantial increase in the proportion of the less stable ketone, over that present at equilibrium. Pyrrolidine appears to be the most effective amine in this process. Hydrolysis of the enamine isomer having a tetrasubstituted double bond proceeds with little or no stereoelectronic control during the protonation step. Low temperature thermal isomerization of simple enamines is shown not to exist; when equilibration does occur, it is due to traces of acid impurity.

The structures of the hydrogen halide salts of glutaronitrile and related compounds, and their conversion to dihydropyridines

Abstract The constitutions of the hydrogen halide salts of glutaronitrile are shown by NMR analysis, to be 2,2-dihalo-6-amino-2,3,4,5-tetrahydropyridinium halids (VIII). A simple procedure for converting these materials to 2-amino-6-halo-3,4-dihydropyridines is described. The latter, which are reasonably stable, represent a new and reactive class of functionally substituted dihydropyridines. Salts derived from several other substituted glutaronitriles have also been examined and proof of their structures is presented.

The structures of the hydrogen halide salts of succinonitrile and related compounds

Abstract The constitutions of the hydrogen halide salts of succinonitrile are shown to be 2-amino-5,5-dihalo-1-pyrrolinium halides (II) and are thus the next lower homologs of the corresponding salts of glutaronitrile.1 On the other hand the homologous 2,3-diphenyl-succinonitrile when treated with hydrogen bromide leads to 5-amino-2-bromo-3,4-diphenyl-3 H -pyrrole hydrobromide (IX) which is tautomerically different from the analogous salt obtained previously from 2,5-diphenylglutaronitrile. The hydrolysis of IX has been examined and the products completely characterized. 2,2,3,3-Tetramethylsuccinonitrile in ether affords 5-imino-3,3,4,4-tetramethyl-2-pyrrolidone hydrobromide when treated with anhydrous hydrogen bromide whereas 1,1′-dicyano-1,1′-bicyclohexyl is unreactive towards this gas, in aprotic solvents.