Cyclic 2:1 and 1:2 Aldehyde‐to‐Acetone Byproduct Adducts in Aldol Reactions Promoted by Supported Proline‐Incorporated Catalysts

Abstract

Significant amounts of cyclic byproducts of aldol addition with stoichiometry deviating from a regular 1:1 addition pattern were formed when the reaction of acetone with aromatic aldehydes was promoted by polymer‐supported proline‐incorporated catalysts. These adducts, unprecedented in the context of the aldol reaction, are most probably formed via a multistep domino mechanism.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

Asymmetric Synthesis and Application of Homologous Pyrroline‐2‐alkylboronic Acids: Identification of the B–N Distance for Eliciting Bifunctional Catalysis of an Asymmetric Aldol Reaction.

“…1 H NMR (CDCl 3 , 400 MHz, mixture of rotamers): δ H =1.43 (br s), 1.48 (br s, 9H in total), 1.84–2.15 (m, 4 H), 3.42–3.59 (m, 2 H), 4.02–4.21 (m, 1 H), 9.45–9.56 ppm (m, 1 H). All other spectroscopic and analytical data were identical to those reported in the literature 19…”

“…0.27 (EtOAc/ n ‐hexane, 1:1 as eluent); 1 H NMR (700 MHz, CDCl 3 ): δ H =2.67 (dd, J =14.7, 11.8 Hz, 2 H), 2.83 (dd, J =14.7, 2.4 Hz, 2 H), 5.01 (dd, J =11.8, 2.4 Hz, 2 H), 7.66–7.63 (m, 4 H), 8.31–8.28 ppm (m, 4 H); 13 C NMR (151 MHz, CDCl 3 ): δ C =49.1, 78.1, 124.3, 126.5, 147.1, 148.0, 203.3 ppm; IR ν max (neat): $\tilde \nu $ =1721 (CO), 1518 (Ar), 1346 cm −1 (NO 2 ); LRMS (atmospheric solids analysis probe (ASAP)): m/z : 361.1 (20 %), 360.1 (100 %) [ M +NH 4 ] + , 156.1 (40 %); HRMS (ASAP): m/z : calcd for C 17 H 18 N 3 O 6 : 360.1190 [ M +NH 4 ] + ; found: 360.1183. All spectroscopic and analytical data were identical to those reported in the literature 19…”

Assessment of migration regularity of phthalates from food packaging materials

“…Then, the segment is free to rotate with the number of conformations is increased, and the shape of the molecular chain changes. Finally, the cavity is formed inside the lunch box, and the free energy obtained by the PAEs is increased by the temperature, so that it can get rid of the interaction force between the PP molecules, and migrate from the polymer successfully (Silva, Freire, Sendon, Franz, & Losada, 2009). In addition, the Arrhenius empirical formula shows that as the temperature rises, the activation energy of small molecules increases accordingly, which is more conducive to material migration.…”

Effects of dendritic interface on enantioselective catalysis by polymer-bound prolines

“…In addition, the product 3 of Robinson annulations of acetone with the enone byproduct 2 was found in the mixtures of the reactions involving benzaldehyde (but not nitrobenzaldehyde). 17 Repeated experiments showed that the reaction conversion and yield were very sensitive to slight changes in the reaction conditions, particularly the water content. Thus, when 5 equivalents of water were added to the reaction mixture, quantitative conversion was observed (rather than 74%), but the yield was lower (53% vs. 55%).…”