Synthesis of 2,3-dichlorobicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid N-carboxyphenylimides

Abstract

A I C COOH Cl N Cl Cl O O R IVа _ IVc Compounds of bicyclo[2.2.1]hept-and [2.2.2]oct-5-ene series exhibit a wide range of biologic and physiologic action [1][2][3][4][5][6]. They are synthesized using primary amines and cyclopentadiene and 1,3-cyclohexadiene as dienes.We formerly studied the synthesis of similar compounds using as primary amines various functionally substituted amines: aminonitriles, nitramines etc. [2,[4][5][6][7][8]. Here we report on the syntheses of new monoand bicyclic compounds proceeding from o-, m-, and p-aminobenzoic acids.First we investigated the reaction of dichloromaleic anhydride (I) and aminoacids IIa-IIc giving N-arylimides of dichloromaleic acid IIIа-IIIc. In the fi rst stage of the process amidoacids А are formed [6] which under the reaction condition undergo further cyclization into the corresponding imides. Judging from the yields of compounds IIIа-IIIc the reactivity of isomeric aminobenzoic acids decreses in the series para-, meta-, ortho-due to the growing steric hindrance to the formation of the planar dichloromaleic acid N-arylimide [9].The composition and structure of synthesized compounds IIIа-IIIc were confi rmed by the elemental analysis, IR and 1 Н NMR spectroscopy. The formation of the assumed structure is indicated by the presence of groups =СО, -СООН, chlorine and tertiary nitrogen atoms. In the 1 Н NMR spectra of compounds IIIа-IIIc the proton signals are registered in the following regions, δ, ppm: 10.3 and 11.5 (СООН), 7.20 and 7.99 (С 6 Н 4 ).Synthesized dichloromaleic acid N-arylimides IIIа-IIIc possess four electron-acceptor groups resulting in their high reactivity in the diene synthesis involving cyclopentadiene.The composition and structure of synthesized adducts were confi rmed by the elemental analysis, IR and 1 Н NMR spectroscopy. In the IR spectrum of adduct IVb the absorption bands were present of the vibration of the benzene ring at 1630-1536 cm -1 and also of the stretching and bending vibrations of the С-Н bond (3000, 1440 cm -1 ). The bands in the region of 2950-2880 [δ(=CH)] and 960-820 cm -1 [δ(C-H)] indicate the presence in the molecule of a strained double bond.In the 1 Н NMR spectrum of imide IVc the protons of the six-membered ring of the norbornene fragment form a spin system АА 1 ХХ 1 where А and А 1 are protons Н 1,4 , δ 3.44 ppm, and Х and Х 1 are protons Н 5,6 , δ 6.45 ppm. The bridging methylene protons are nonequivalent and appear as an АВ system with δ(Н А ) 2.19, δ(Н В ) 2.50 ppm, R = о-СOOH (а), m-СOOH (b), p-СOOH (c).

Synthesis of New Halogen-Containing Norbornene Adducts Based on N-Substituted Imides of 2,3-Dichlorbicyclo [2.2.1] Hept-5-ene-2,3- Dicarboxylic Acids and Hexachlorocyclopentadiene

“…Previously, we investigated the diene condensation of N-substituted imidates of dichloromaleic acid with cyclopentadiene and 1,3cyclohexadiene, leading to the formation of bicyclic adducts. The structure and properties of the synthesized compounds were studied, as well as certain patterns of reactions [15][16][17][18][19][20].…”