Daniel L. Comins

Regioselective Substitution in Aromatic Six-Membered Nitrogen Heterocycles

Publisher Summary The reactivity of various six-membered heteroaromatic compounds has been previously reviewed through 1982. This chapter describes the nucleophilic, electrophilic, and free-radical substitution reactions on the ring carbon atoms of pyridines, pyridazines, pyrimidines, pyrazines, triazines, and tetrazines. Fused-ring derivatives of these heterocycles are not covered. Multistep substitutions involving dihydro intermediates are included. The primary chemical literature between 1982 and June 1987 is also surveyed.

Ortho lithiation of 2-, 3-, and 4-methoxypyridines

Abstract The ortho lithiation of 2-,3-, and 4-methoxypyridine was effected using mesityllithium as the metalating base.

Regioselective addition of titanium enolates to 1-acylpyridinium salts. A convenient synthesis of 4-(2-oxoalkyl)pyridines

Abstract Titanium enolates add to the 4-position of 1-phenoxycarbonylpyridinium salts to give 1,4-dihydropyridines; subsequent aromatization provides 4-(2-oxoalkyl)pyridines.

Synthesis of 3-acylpyridines utilizing a friedel-crafts reaction

Abstract A synthesis of 3-acylpyridines via a Friedel-Crafts acylation of a dihydropyridine intermediate is described.

The addition of alkylzinc iodides to 1-(phenoxycarbonyl)-2,3-dihydropyridinium salts. A synthesis of 2-alkyl-Δ3-piperidines.

Abstract Several 2-alkyl-1-(phenoxycarbonyl)-Δ 3 -piperidines were prepared by the addition of alkylzinc iodides to 1-(phenoxycarbonyl)-2,3-dihydropyridinium salts.

A one-pot alkylation of aromatic aldehydes

The addition of aromatic aldehydes to lithium N-methylpiperazide in benzene gave α-amino alkoxides which were ortho-lithiated with excess n-butyllithium. Subsequent alkylation and hydrolysis provided ortho-substituted aromatic aldehydes via a one-pot reaction.

The in situ protection of aldehydes via α-amino alkoxides

Abstract Aromatic and aliphatic aldehydes can be protected in situ via the formation of α-amino alkoxides and their O-trimethylsilyl derivatives.

Synthesis of 3-substituted indoles via N-acylindolium ions

Abstract 3-Substituted N-(N′N′-diethylcarbamyl)indoles are prepared from indole-3-carboxaldehyde in good overall yield via N-acylindolium ion intermediates.

Synthesis and synthetic utility of 1-acyl-2-alkyl-4-trimethylstannyl-1,2-dihydropyridines

Abstract 1-Acyl-2-alkyl-1,2-dihydropyridines were prepared from 4-trimethylstannylpyridine and Grignard reagents. This methodology was utilized in the synthesis of N-methyl-2-azatricyclo[5.3.1.0]undecane.

The addition of alkylzinc iodides to 1-(phenoxycarbonyl)pyridinium salts

Abstract Several 1-(phenoxycarbonyl)-1,2-dihydropyridines were prepared by the addition of alkylzinc iodides to 1-(phenoxycarbonyl)pyridinium salts.