Synthesis in Green Solvents

Orha, László; Akien, Geoffrey R.; Horváth, István T.

doi:10.1002/9783527628698.hgc075

Cited by 2 publications

(1 citation statement)

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“…Green chemistry or sustainable chemistry is defined by the U.S. Environmental Protection Agency (EPA) as “the design of chemical products and processes that reduce or eliminate the use or generation of hazardous substances”. − In recent years, the most pivotal area in green synthesis has been fostered by the search for environmentally benign reaction media to replace commonly used organic solvents in chemical processes − or designing one-pot reactions to construct diverse molecular libraries. , Toward fulfilling these goals, multicomponent reactions (MCRs) − can be recognized as one of the most direct, effective, and rapid methods for greener organic synthesis.…”

Section: Introductionmentioning

confidence: 99%

A Three-Component Catalyst-Free Approach to Regioselective Synthesis of Dual Highly Functionalized Fused Pyrrole Derivatives in Water–Ethanol Media: Thermodynamics versus Kinetics

Chen

Liu

Yang

et al. 2014

ACS Sustainable Chem. Eng.

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A three-component catalyst-free protocol for the regioselective synthesis of dual highly functionalized fused pyrroles has been developed from a cascade [3 + 2] cyclization of heterocyclic ketene aminals (HKAs) 1 with arylglyoxal monohydrates 2 and cyclohexane-1,3-diones 3 in water–ethanol media. The kinetically controlled products 4 could be synthesized within 1 h but would irreversibly transform to thermodynamically controlled products 5 over an additional 5 h. At the same time, the transformative synthesis of 5a from 4a by controlling the oxygen or nitrogen proved the proposed mechanism. Furthermore, the DFT calculation also corroborated that the stability of products 5 are a 100,000 times more thermodynamically stable than products 4. Finally, the origin of the greater stability of 5 could be explained by the reduced density gradient (RDG) analysis, which hinted that the crucial factors are the formation of a new intramolecular hydrogen bond and the release of the steric effect of the crowded rings. In conclusion, this novel synthetic strategy offers an alternative method using thermodynamic or kinetic control for regioselective construction of biologically meaningful fused pyrrole architectures from a concise, rapid, and environmentally friendly vision.

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