Efficient synthesis of 4-substituted-ortho-phthalaldehyde analogues: toward the emergence of new building blocks

• Clémence Moitessier,
• Ahmad Rifai,
• Pierre-Edouard Danjou,
• Isabelle Mallard and
• Francine Cazier-Dennin

Beilstein J. Org. Chem. 2019, 15, 721–726, doi:10.3762/bjoc.15.67

• chloride/N,N-dimethylformamide in the presence of a catalytic amount of p-toluenesulfonic acid ended up with only the formation of OPA. Regeneration of phenols from methyl ethers have also been tested by Boovanahalli et al. [26] by using an ionic liquid such as 1-butyl-3-methylimidazolium bromide ([Bmim]Br

• key intermediate 4,5-dihydroisobenzofuran-5-ol (3) before reaching the oxidation step. The methoxy protecting group and the DDQ oxidation reagent were found to be the most efficient. Moreover, deprotection of 4-methoxy-ortho-phthalaldehyde (5b) was successfully achieved using [Bmim]Br and p-TsOH on

• compound 5b (200 mg, 1.2 mmol), p-TsOH (1.68g, 9.8 mmol) and [Bmim]Br (4.0 g, 18.3 mmol) was placed in a sealed vial and irradiated under microwave irradiation for 30 minutes at 150 °C under strong agitation. After cooling, the mixture was vigorously extracted with Et2O overnight. The ether layer was

Bi-mediated allylation of aldehydes in [bmim][Br]: a mechanistic investigation

• Mrunesh Koli,
• Sucheta Chatterjee,
• Subrata Chattopadhyay and
• Dibakar Goswami

Beilstein J. Org. Chem. 2018, 14, 2198–2203, doi:10.3762/bjoc.14.193

• temperature ionic liquid (RTIL), [bmim][Br] has been found to be a superior medium for the Bi-mediated Barbier-type allylation of aldehydes compared to other conventional solvents. It plays the dual role of a solvent and a metal activator enabling higher yields of the products in a shorter reaction time using

• stoichiometric/near-stoichiometric amounts of reagents. Plausibly, [bmim][Br] activates Bi metal by a charge transfer mechanism. The 1H VT-NMR studies suggested that both the allylating species, allylbismuth dibromide and diallylbismuth bromide, are generated in situ. Keywords: allylation; bismuth; [bmim][Br

• ineffective (Table 1, entry 15). True to our expectation, the reaction was very fast in [bmim][Br] and furnished 2a in 88% yield. Notably, the reaction proceeded to completion with almost stoichiometric amounts of allyl bromide (1.2 equiv) and Bi (1.0 equiv) in absence of any additional metal activator (Table

5-Aminopyrazole as precursor in design and synthesis of fused pyrazoloazines

• Ranjana Aggarwal and
• Suresh Kumar

Beilstein J. Org. Chem. 2018, 14, 203–242, doi:10.3762/bjoc.14.15

• ) and α,β-unsaturated ketones 24 (Scheme 3) in the ionic solvent [bmim]Br at 90 °C with excellent yield. Variation of the aryl substituents on the α,β-unsaturated ketones 24 has no significant effect on the reaction. The reaction was proposed to occur through a sequence of Michael addition, cyclization

• -aminopyrazole 16 and aldehydes 47 in various organic solvents and ionic liquids to synthesize pyrazolo[3,4-b]pyridine derivative 87 (Scheme 23). Ionic liquids provided high yields of 87 in very short time with the best results obtained in [bmim]Br whereas organic solvents resulted in low yields and took longer