Reaction of Cyclopropenones with Heteroaromatic Nitrogen Compounds

Abstract

Diphenylcyclopropenone reacts with a variety of heteroaromatic nitrogen compounds to give in good yield either (a) 1,2-diphenyl-3-indolizinyl cis-1,2-diphenyl acrylates and aza analogs, (b) 5,6-diphenyl-7-hydroxypyrrolo[l,2-blpyridazines and similar structures, or (c) adducts in which cycloaddition takes place to an N=N bond. Proof of structure of the new heterocycles is based on deuterium labelling experiments, hydrogenolysis to known compounds, and the preparation of chloro and iminoether derivatives. Cycloheptenocyclopropenones in the examples studied form heterocycles of type b.La diphtnylcyclopropknone rtagit avec une varittt de composes htttroaromatiques contenant de I'azote et conduit avec de bons rendements soit (a) aux cis-diphtnyl-1,2 acrylates (et leurs analogues azotes) de diphknyl-1,2 indolizinyle-3, (b) aux diphknyl-5,6 hydroxy-7 pyrrolo[l,2-blpyridazines et structures similaires, ou (c) des composes d'addition dans lesquels la cycloaddition se fait sur le lien -N=N-.Les preuves de structure de ces composts sont bastes sur des experiences impliquant des marquages par le deuttrium, des hydrogtnolyses conduisant a des composes connus et la preparation de dtrivts chlorts et iminoethers. Dans les cas examints, les cyclohepttnocycloproptnones conduisent des htttrocycles du type b.

Reaction of Diphenylcyclopropenethione with Heteroaromatic Nitrogen Compounds

“…This fact together with their facile oxidation to the disulfides presumably account for the observed lack of reactivity of the thione 1 towards pyridine and picolines. In contrast, as has been shown by Breslow and by the present authors, 2 reacts very vigorously under such conditions to form 1,2-diphenyl-3-indolizinyl-cis-l,2-diphenylacrylates like 13(1,2).…”

“…The thione shows a marked propensity for addition to nitrogen-nitrogen double bonds whereas 2 undergoes such additions principally when addition to a carbon-nitrogen bond is precluded structurally (e.g. benzo [clcinnoline (1)). In addition, the inability of the thione 1 to form sulfur analogs of indolizinyl cis-1,2-dip1.snylacrylates led to different behavior towards e.g.…”

Synthesis of 5-Substituted Pyrrolo[1,2-b]pyridazines with Antioxidant Properties

“…Reaction of the pyrrolo [1,2-b]pyridazin-5-ol 3 with tosyl chloride in the presence of DMAP and triethylamine gave the tosylate 12. It has been reported that 5-chloropyrrolo [1,2-b]pyridazine 15* is formed when pyrrolo [1,2-b]pyridazin-5-ol 3 is reacted with phosphorus oxychloride [5] , but this procedure gave, in our hands, only the phosphate 14 after work-up using ethanol. Work-up without nucleophilic solvents gave compound 13 (Scheme 2).…”

“…---* Lown and Matsumoto actually reported the synthesis of 5-chloropyrrolo [1,2-b]pyridazin 16 (see Scheme 2) from pyrrolo [1,2-b]pyridazin-5-ol [5] , but later Weidner et al showed that the hydroxy group in the starting material must have been situated in the indolizine 1-position [4] .…”

Pyrrolo[1,2-a]quinoxalines based on quinoxalines (Review)

“…In these reactions, 2-methylquinoxaline (51b) acts as a synthetic equivalent of synthon D and, depending on the second reagent, is converted into the 1-hydroxy or 1-mercapto derivatives of pyrrolo-[1,2-a]quinoxaline 85 [41,42]. However, a more recent investigation, involving study of the reaction of diphenylcyclopropenone with quinoxaline and 2-methylquinoxaline, showed that the 3-hydroxy derivative of pyrrolo[1,2-a]quinoxaline 86 [43] and not the 1-hydroxy derivative 85b, as reported previously [41], is formed as a result of this reaction.…”