David J. Lythgoe

Triazolopyridines. 18. Nucleophilic substitution reactions on triazolopyridines; a new route to 2,2′-bipyridines☆

Abstract The synthesis of some 5-, 6-, and 7-halogenotriazolopyridines is described, and their reactions with nucleophiles. The formation of 7,7′-bitriazolopyridines provides a new synthesis of 2,2′-bipyridines.

RP 70676: A potent systematically available inhibitor of acyl-CoA:cholesterol O-acyl transferase (ACAT)

Abstract RP 70676 (3d) is a potent inhibitor of ACAT. It is an effective hypocholesterolaemic agent in the cholesterol-fed rabbit, and reduces the accumulation of both cholesterol and cholesterol ester in rabbit aorta and thoracic artery. The compound is readily bioavailable in rabbits with significant levels of parent compound present in plasma up to 6 hours after an oral dose.

Triazolopyridines. 16 1. lithiation of 3-cyano[1,2,3]triazolo[1,5-a]-pyridine

Abstract Various methods for the synthesis of 3-cyanotriazolopyridine 8 by diazo transfer to 2-pyridylacetonitrile are described. Lithiation of the triazolopyridine 8 using LDA or TMPA followed by quenching with TMS chloride, gave the 4-mono-, the 7-mono-, and the 4,7- di TMS derivatives 14,18, and 15, and the amidines 16 and 17, in contrast to the previously reported regiospecific attack at position 7. A Grignard reaction on compound 8 gave 3-propionyl triazolopyridine, 13.

4-Unsubstituted, 5-Amino and 5-Unsubstituted, 4-Aminoimidazoles

Publisher Summary This chapter deals with the chemistry of 4 and 5-aminoimidazoles, the compounds of recently recognized biological importance. In most living systems, 5-amino-1-(β-D-ribofuranosyl)-imidazole-5’-monophosphate (AIR) is an intermediate in the de novo biosynthesis of purine ribonucleotides. It is also used as a biosynthetic precursor of thiamin in some lower organisms. This important aminoimidazole derivative is also used as a synthetic intermediate for the chemistry of simple 5-aminoimidazoles and the isomeric 4-aminoimidazoles. The stabilities and reactivities of monoaminoazoles vary considerably, and are related to the number of nitrogen atoms in the heterocyclic ring. Nitrogen atoms stabilize dipolar canonical forms that contribute significantly to the electronic structure. The chapter also describes the physical properties and theoretical studies of aminoimidazoles that includes studies concerning spectroscopic methods, 13 C and I5 N NMR spectroscopy, ultraviolet spectroscopy, and infrared and mass spectroscopy. The chapter considers the imidazoles with the absence of a substituent on the ring carbon atom adjacent to the amino substituent.

A novel synthesis of purine and deazapurine derivatives from 5-aminoimidazoles

Catalytic reduction of 4-unsubstituted-5-nitroimidazoles (3) in 1,4-dioxane solution is an excellent route to the 5-aminoimidazoles (1) which can be isolated or used in situ to generate good yields of purine or deazapurine derivatives.

Reactions of thionyl chloride with C-methyl heterocycles. Part 1. The formation of dichloro(2-quinolyl)methanesulphenyl chlorides from 2-methylquinolines

Hot thionyl chloride converts 2-methylquinolines (1) into dichloro(2-quinolyl)methanesulphenyl chlorides (2) which upon treatment with secondary amines are transformed into thioamides (7). Reaction of the novel derivatives (2) with amidines gives 5-(2-quinolyl)-1,2,4-thiadiazoles (8) and reaction with anionic nucleophiles results in substitution at sulphur.

Reactions of thionyl chloride with C-methyl heterocycles. Part 2. The formation of [1,2]dithiolo[3,4-c]quinolin-1-ones and bis[dichloro(4-quinolyl)methyl]trisulphanes from 4-methylquinolines

4-Methylquinolines (1) react with hot thionyl chloride to give either 4-chloro[1,2]dithiolo[3,4-c]quinolin-1-ones (2) or bis[dichloro(4-quinolyl)methyl]trisulphanes (18). The mode of formation of these products is discussed and their reactions with various reagents are described.

Synthesis of 1,3-disubstituted-pyrrolo[2,1-a]isoquinoline-2-carboxylic acids, esters and amides

A number of 1,3-disubstituted pyrrolo [2,1-a] isoquinoline-2-carboxylic esters have been prepared using a variety of independent routes. The corresponding acids and a range of amides were subsequently synthesised. The primary amides were found to differ significantly from those reported to arise from the reaction between the anion of an isoquinoline Reissert compound and an α,β-unsaturated nitrile. Re-investigation has established that the latter reaction does not produce primary amides. The true nature of the products as 2-acyl-3-aminopyrrolo[2,1-a]isoquinolines was established using X-ray crystallography.