Discovery and SAR of N-(1-((substituted piperidin-4-yl)methyl)-3-methoxypiperidin-4-yl)-2-methoxybenzamide derivatives: 5-Hydroxytryptamine receptor 4 agonist as a potent prokinetic agent.

A series of novel benzamide derivatives, altering the 4-fluorophenylalkyl moiety in cisapride, were synthesized as 5-HT4 receptor agonists, and SAR of these analogs was examined on in vitro and in vivo prokinetic activities. These compounds were synthesized for high 5-HT4 receptor binding affinities and low hERG affinities. Several types of analogs were obtained and screened for 5-HT4 binding, hERG blocking, agonism, and gastric emptying assessment.

Regioselective synthesis of 3-alkynyl-5-bromo-2-pyrones via Pd-catalyzed couplings on 3,5-dibromo-2-pyrone.

[reaction: see text] 3,5-Dibromo-2-pyrone underwent facile Pd(0)-catalyzed coupling reactions with various alkynes to give rise to the corresponding 3-alkynyl-5-bromo-2-pyrones with good to excellent chemical yields and regioselectivity.

Diels-Alder cycloadditions of 3,5-dibromo-2-pyrone: a new ambident diene.

D-A cycloadditions of 3,5-dibromo-2-pyrone were investigated with a series of electronically and sterically distinct dienophiles. Our results showed that it is a highly potent ambident diene, being more reactive and stereoselective than monobromo-2-pyrones, and thus capable of generating a variety of bicycloadducts in much higher chemical yields and endo/exo ratios than monobromo-2-pyrones. Another interesting feature of this study is that the two bromine groups on the cycloadducts could be independently manipulated to produce other synthetically useful bicyclolactones.