Antiallergics: 3-(1H-tetrazol-5-yl)-4H-pyrimido[2,1-b]benzothiazol-4-ones

Abstract

A short series of the title compounds was prepared and evaluated for both antiallergic and bronchodilator activity. Members of the series exhibit good oral activity in the rat PCA test, the most potent being the parent compound, 3-(1H-tetrazol-5-yl)-4H-pyrimido[2,1-b]benzothiazol-4-one, and its 8-chloro derivative. The latter two compounds are considerably more potent than either disodium chromoglycate or theophylline as antiallergic agents and also show significant bronchodilator activity.

A New and Efficient Method for the Synthesis of Pyrimido[2,1-<i>b</i>]Benzothiazole Derivatives

“…The 6a-e products exhibited a singlet in 1 H spectra at about δ = 5.54 -6.33 ppm for H-4 and also a distinguished peak at δ = 50.9 -56.5 ppm for C-4 in 13 CNMR spectroscopy. The 6f-g products demonstrated a singlet in 1 H spectra at δ = 9.02 -10.2 ppm for H-3 and also a distinguished peak at δ = 110.9 -116.2 ppm for C-3 in 13 CNMR spectroscopy. The mass spectra of these compounds displayed molecular ion peaks.…”

“…The structures of compounds 6a-g were deduced from their 1 H NMR, 13 C NMR and IR spectral data and also by mass spectrometry. The 6a-e products exhibited a singlet in 1 H spectra at about δ = 5.54 -6.33 ppm for H-4 and also a distinguished peak at δ = 50.9 -56.5 ppm for C-4 in 13 CNMR spectroscopy.…”

“…The structures of compounds 6a-g were deduced from their 1 H NMR, 13 C NMR and IR spectral data and also by mass spectrometry. The 6a-e products exhibited a singlet in 1 H spectra at about δ = 5.54 -6.33 ppm for H-4 and also a distinguished peak at δ = 50.9 -56.5 ppm for C-4 in 13 CNMR spectroscopy. The 6f-g products demonstrated a singlet in 1 H spectra at δ = 9.02 -10.2 ppm for H-3 and also a distinguished peak at δ = 110.9 -116.2 ppm for C-3 in 13 CNMR spectroscopy.…”

“…Pyrimidobenzothiazole derivatives have also been known for their antimicrobial properties [8][9][10], anti-allergy [11], antitumor and anti-viral activities [12]. Meanwhile, oxopyrimido benzothiazoles have been assessed for bronchodilators, and bronchial asthma treatment [13]. Besides, these types of compounds, especially those with amide groups, show incredibly potent anti-inflammatory, anticoagulant, anti-fungicidal and anti-herbicidal activities and are used in the chemotherapy of carcinoid patients [14][15][16][17].…”

Reagent-controlled regiodivergent intermolecular cyclization of 2-aminobenzothiazoles with β-ketoesters and β-ketoamides

“…As trace amounts of benzo[4,5]thiazolo[3,2- a ]pyrimidin-4-ones, 5a , were observed in the synthesis of benzo[ d ]imidazo[2,1- b ]-thiazoles, we searched for a suitable reagent to regioselectively form this instead of 3a and 4 . This tricyclic backbone can be found in compounds that possess a wide range of medicinal properties including those with antimalarial [ 74 ], anticancer [ 75 – 76 ], antiallergic [ 77 – 78 ], antibacterial [ 79 ], and antimicrobial properties [ 80 – 81 ]. In addition, they have been found to be biologically active antagonists of adenosine receptors [ 82 ], inhibitors of cyclic-AMP-diphosphoesterase [ 83 ], and benzodiazepine receptor ligands [ 84 – 85 ].…”