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An efficient organocatalyst for iminium-ion based asymmetric Diels-Alder (DA) reactions has been rationally designed. The most influential structure-activity relationships were determined experimentally, while DFT calculations and NMR studies provided further mechanistic insight. This knowledge guided an in silico screening of 62 different catalysts using an ONIOM(B3LYP/6-31G*:AM1) transition-state modeling, which showed good correlation between theory and experiment. The top-scored compound was easily synthesized from levoglucosenone, a biomass-derived chiral enone, and evaluated in the DA reaction between (E)-cinnamaldehyde and cyclopentadiene. In line with the computational finding, excellent results (up to 97% ee) were obtained. In addition, the catalyst could be easily recovered and reused with no loss in its catalytic activity. [ABSTRACT FROM AUTHOR]

Abstract: An experimental and computational study was conducted to assess the effect of chlorine and bromine substitution in Diels–Alder reactions involving chiral α-halo enones as dienophiles. An important rate enhancement was observed in the case of acyclic dienes, while the use of cyclic dienes resulted in prolonged reaction times and lower yields. DFT calculations suggest that these reactions are governed by finely balanced geometric and electronic features at the TSs. [Copyright &y& Elsevier]

Microwave-assisted asymmetric Diels-Alder reactions using levoglucosenone-derived chiral auxiliaries have been investigated. The cycloaddition reaction between the corresponding chiral acrylate and cyclopentadiene showed important rate enhancements under microwave irradiation compared to conventional heating conditions, whereas the yields and diastereoselectivities were not significantly affected. [ABSTRACT FROM AUTHOR]

Abstract: Chiral alcohols were designed and easily prepared from levoglucosenone, a biomass-derived valuable synthon. These alcohols were tested as chiral auxiliaries in asymmetric Diels–Alder reactions between the corresponding acrylates with acyclic and cyclic dienes. The regio, stereo, and facial selectivity varied from very good to excellent, depending upon the benzylic substitution of the auxiliary and the diene employed. As a consequence, after removal of the auxiliary, the resulting carboxylic acid derivatives were obtained in 72–99% ee. [Copyright &y& Elsevier]

Abstract: New chiral auxiliaries derived from levoglucosenone were developed in a simple and efficient way and evaluated as chiral inductors in asymmetric Diels–Alder reactions between the corresponding acrylate derivatives and cyclopentadiene. The results showed an important influence of the absolute configuration of the C(2) center of the auxiliary on the level of stereoinduction obtained. [Copyright &y& Elsevier]

The effect of an extra EWG in the reactivity and regioselectivity in Diels–Alder reactions of β-cyanolevoglucosenone and 4 different dienes was studied by a joint computational and experimental study. Conceptual DFT analysis successfully predicted an important enhancement in the reactivity, and correctly anticipated the regioselectivity in the reactions with isoprene. However, this static treatment failed when dealing the regiochemical preference of the reactions involving a substituted anthracene as diene. MPW1K/6-31G* calculations correctly reproduced the experimental observations. Based on the collected data, we found that when dealing with dienes and dienophiles with no clear electronically activated position, the ease of pyramidalization of the interacting atoms dictates the regioselectivity of the DA reaction. [ABSTRACT FROM AUTHOR]

Abstract: An appealing inversion in the regiochemical outcome of Diels–Alder reactions between levoglucosenone (1) and its α-bromo derivative (5) with isoprene (2) was studied computationally. Based on different DFT calculations we concluded that both reactions should display the same regioselectivity. This result was further validated experimentally. [Copyright &y& Elsevier]

Diels–Alder cycloaddition between an enantiomerically pure protected cis -cyclohexadiene diol metabolite and optically pure levoglucosenone derived from cellulose gave rise to complex pentacyclic natural product like structures in a chemically succinct process. The adducts were fully characterized and the observed results were in accord with theoretical calculations performed on the possible course of the reaction. [ABSTRACT FROM AUTHOR]

Abstract: The Diels–Alder reaction of a pyranose-derived nitroalkene 1 with cyclopentadiene is described, and the unexpected facial selectivity of the cycloaddition is analyzed by a computational study. [Copyright &y& Elsevier]