A novel synthetic approach to hydroimidazo[1,5-b]pyridazines by the recyclization of itaconimides and HPLC–HRMS monitoring of the reaction pathway

• Dmitry Yu. Vandyshev,
• Khidmet S. Shikhaliev,
• Andrey Yu. Potapov,
• Michael Yu. Krysin,
• Fedor I. Zubkov and
• Lyudmila V. Sapronova

Beilstein J. Org. Chem. 2017, 13, 2561–2568, doi:10.3762/bjoc.13.252

• University, Miklukho-Maklaya St., 6, Moscow 117198, Russian Federation 10.3762/bjoc.13.252 Abstract The novel cascade two-stage reaction between itaconimides and 1,2-diamino-4-phenylimidazole proceeds regio- and chemoselectively to form tetrahydroimidazo[1,5-b]pyridazines and includes nucleophilic C

• -addition by the activated C=C double bond and subsequent intramolecular recyclization of the intermediate with the amino group involved. Keywords: cascade reaction; diaminoimidazoles; HPLC–HRESIMS; imidazo[1,5-b]pyridazines; itaconimides; Introduction Among the numerous bicyclic fused imidazole

• virtually any carbon atom of the heterocyclic system is achievable in addition to hydrogenated imidazo[1,5-b]pyridazines [34][35]. Itaconimides, in contrast to itaconic acid, its esters, monoamides or anhydride [36][37], scarcely have been studied in the synthesis of heterocyclic compounds. The presence of

Highly chemo-, enantio-, and diastereoselective [4 + 2] cycloaddition of 5H-thiazol-4-ones with N-itaconimides

• Shuai Qiu,
• Choon-Hong Tan and
• Zhiyong Jiang

Beilstein J. Org. Chem. 2016, 12, 2293–2297, doi:10.3762/bjoc.12.222

• /bjoc.12.222 Abstract A dipeptide-based urea-amide tertiary amine (DP-UAA) was shown to be an effective Brønsted base catalyst for the first asymmetric annulation reaction between 5H-thiazol-4-ones and N-itaconimides. High levels of enantioselectivity (up to 99% ee) and diastereoselectivity (>19:1 dr

• ) were obtained for a series of spirocyclic 1,4-sulfur-bridged piperidinone-based succinimides. Keywords: [4 + 2] annulation; asymmetric organocatalysis; dipeptide-based Brønsted bases; 5H-thiazol-4-ones; N-itaconimides; Introduction Sulfur-containing tetrasubstituted carbon stereocenters are widely

• . Succinimides are present in many biologically significant molecules and are investigated as potential pharmacophores in the research of drug discovery [11][12]. Our group has recently devised N-itaconimides for the assembly of succinimide frameworks [13][14][15][16][17][18]. As an extension of these works